Showing papers in "Journal of Prosthodontics in 2017"

Additive Technology: Update on Current Materials and Applications in Dentistry

Abstract: Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer-aided manufacturing. Research on material for use in additive manufacturing is ongoing, and a wide variety of materials are being used or developed for use in dentistry. Some materials, however, such as cobalt chromium, still lack sufficient research to allow definite conclusions about the suitability of their use in clinical dental practice. Despite this, due to the wide variety of machines that use additive manufacturing, there is much more flexibility in the build material and geometry when building structures compared with subtractive manufacturing. Overall additive manufacturing produces little material waste and is energy efficient when compared to subtractive manufacturing, due to passivity and the additive layering nature of the build process. Such features make the technique suitable to be used with fabricating structures out of hard to handle materials such as cobalt chromium. The main limitations of this technology include the appearance of steps due to layering of material and difficulty in fabricating certain material generally used in dentistry for use in 3D printing such as ceramics. The current pace of technological development, however, promises exciting possibilities.

An In Vitro Study of Factors Influencing the Performance of Digital Intraoral Impressions Operating on Active Wavefront Sampling Technology with Multiple Implants in the Edentulous Maxilla.

Abstract: PURPOSE To evaluate the performance (accuracy and repeatability) and the factors affecting the clinical performance of a recently released intraoral scanner based on active wavefront sampling technology. MATERIALS AND METHODS A single resin model of an edentulous maxilla fitted with six implants inserted at various depths and angulations was measured with a coordinated measuring machine (CMM) at 3 to 5 μm, and this acted as the "true," or reference, values of the study. Six corresponding cylindrical PEEK scanbodies were then mounted onto the implants, and four calibrated observers independently repeated the digital intraoral scan five times with a True Definition (TrueDef) scanner. Using implant position #15 as a reference, five linear and angular measurements were compared with the reference values (CMM), and the data were analyzed via one-way ANOVA and two-sample t-test. RESULTS Mean linear and angular deviations for the TrueDef from CMM measurements were from 5.38 ± 12.61 μm to -26.97 ± 50.56 μm and from 0.16o ± 0.04o to -0.43o ± 0.1o, respectively. Experienced observers performed significantly better than inexperienced ones (p = 0.006), and scan distance (quadrant) significantly affected scanning accuracy (p = 0.003). Visible length of the scanbody affected measurement accuracy (p = 0.0001), while implant angulation did not (p = 0.757). CONCLUSIONS The TrueDef scanner provides measurements within clinically accepted limits. Yet scanbody visibility, observer experience, and scan length remain relevant factors affecting accuracy.

Dental Implant Length and Diameter: A Proposed Classification Scheme.

Abstract: Purpose To propose a length-and-diameter-based classification scheme for dental implants to standardize terminology in the dental literature and communication between interested parties. Materials and Methods This study was mainly based on searching two major resources: published scientific research papers and 14 of the most popular dental implant manufacturers. Indexed databases were searched from January 2004 up to and including February 2016 using the keywords “dental implant length” and “dental implant diameter.” Retrieved titles and abstracts were screened, and related full-text articles were reviewed. Full-text articles that clearly stated the terms and measurements of implants used were included and considered for proposing this classification scheme. Results The initial search for implant diameter and length yielded 1007 and 936 articles, respectively. A total of 85 studies (41 about diameter, 44 about length) were selected and reviewed. The remaining studies (966 about diameter, 892 about length) that did not abide by the eligibility criteria were excluded. The terms “long,” “short,” “standard,” “wide,” and “narrow” were the most commonly used terms in the literature. A classification scheme for implants by diameter and length was proposed. Conclusions Indexed publications contain a variety of terms used by authors to describe diameter and length of dental implants without conformity and standardization. The classification scheme proposed in this article could serve as a reference for interested parties.

An In Vitro Comparison of the Marginal Adaptation Accuracy of CAD/CAM Restorations Using Different Impression Systems.

Abstract: Purpose To compare the marginal adaptation of 3-unit zirconia fixed dental prostheses (FDPs) obtained from intraoral digital scanners (Lava True Definition, Cadent iTero), scanning of a conventional silicone impression, and the resulting master cast with an extraoral scanner (3Shape lab scanner) Materials and Methods One reference model was fabricated from intact, non-carious, unrestored human mandibular left first premolar and first molar teeth (teeth #19 and 21), prepared for a three-unit all-ceramic FDP Impressions of the reference model were obtained using four impression systems (n = 10), group 1 (PVS impression scan), group 2 (stone cast scan), group 3 (Cadent iTero), and group 4 (Lava True Defintion) Then the three-unit zirconia FDPs were milled Marginal adaptation of the zirconia FDPs was evaluated using an optical comparator at four points on each abutment The mean (SD) was reported for each group One-way ANOVA was used to assess the statistical significance of the results, with post hoc tests conducted via Tukey's HSD p < 005 was considered statistically significant All analyses were done using SPSS 220 Results The mean (SD) marginal gaps for the recorded data from highest to lowest were silicone impression scans 814 μm (68), Cadent iTero scan 624 μm (50), master cast scan 502 μm (61), and Lava True definition scan 266 μm (47) One-way ANOVA revealed significant differences (p < 0001) in the mean marginal gap among the groups The Tukey's HSD tests demonstrated that the differences between all groups (silicone impression scan, master cast scan, Lava True definition scan, iTero Cadent scan) were statistically significant (all p < 0001) On the basis of the criterion of 120 μm as the limit of clinical acceptance, all marginal discrepancy values of all groups were clinically acceptable Conclusions Within the confines of this in vitro study, it can be concluded that the marginal gap of all impression techniques was within the acceptable clinical limit (120 μm) Group 4 (Lava True Defintion) showed the lowest average gap among all groups followed by group 2 (stone cast scan), group 3 (Cadent iTero), and group 1 (PVS impression scan); these differences were statistically significant

A Novel Method to Evaluate Precision of Optical Implant Impressions with Commercial Scan Bodies-An Experimental Approach.

Abstract: Purpose Optical transfer is realized with system-specific transfer posts (scan bodies) mounted on dental implants or on implant analogs. This study presents a novel algorithm for creation of geometry on the surface of dental implant scan bodies and examines the precision of the optical acquisition of scan bodies and the precision of the position of the screw-tightened scan bodies on dental implant analogs. Materials and Methods Scan bodies of two different implant manufacturers (S1, S2), one with a horizontal and two with different conical implant-abutment geometries were screw tightened to implant analogs in stone casts with a 10 Ncm torque. The stone casts were scanned ten times with a dental lab scanner. Each scan body was removed and positioned ten times; after each repositioning, a scan was performed. The cylinder axis of every scan body and the occlusal horizontal scan body surface was virtually reconstructed. At the intersection of the cylinder axis and the horizontal plane a point was marked. The mean deviation of this point in consecutive scans and the angle between the scan body axes in the virtual models were measured, and the standard deviation was calculated. Statistical significance of the results was tested with a Kruskal-Wallis Test and Mann-Whitney U-test for pairwise comparison (p < 0.05). Results The mean deviation of the angle between two scan bodies was 0.05° (SD 0.04°) (S1) and 0.14° (SD 0.08°) (S2). After detachment and repositioning of the scan bodies the mean deviation was 0.05° (SD 0.03°) (S1) and 0.16° (SD 0.08°) (S2). The mean deviation of the central point was 5.7 μm (SD 3.4 μm) without detachment and 4.9 μm (SD 2.6 μm) after detachment and repositioning (S1). For system S2 the mean deviation of the central point was 13.4 μm (SD 7.2 μm) after repeated scanning and 15 μm (SD 5 μm) after detachment, repositioning, and repeated scanning. Conclusions The precision of extraoral scanning of scan bodies is dependent on the scan body surface design and geometry. The precision of scanning with an extraoral model scanner differed between the scan body geometries and inter-scan body distances. The precision of dental implant scan body scanning was not significantly influenced by detachment and repositioning of the scan body.

Bruxism in Movement Disorders: A Comprehensive Review

Abstract: Bruxism is an abnormal repetitive movement disorder characterized by jaw clenching and tooth gnashing or grinding. It is classified into two overlapping types: awake bruxism (AB) and sleep bruxism (SB). Theories on factors causing bruxism are a matter of controversy, but a line of evidence suggests that it may to some extent be linked to basal ganglia dysfunction although so far, this topic has received little attention. The purpose of this article was to review cases of bruxism reported in various movement disorders. The biomedical literature was searched for publications reporting the association of bruxism with various types of movement disorders. As a whole, very few series were found, and most papers corresponded to clinical reports. In Parkinsonian syndromes, AB was rarely reported, but seems to be exacerbated by medical treatment, whereas SB is mainly observed during non-REM sleep, as in restless leg syndrome. AB is occasionally reported in Huntington's disease, primary dystonia, and secondary dystonia; however, its highest incidence and severity is reported in syndromes combining stereotypies and cognitive impairment, such as Rett's syndrome (97%), Down syndrome (42%), and autistic spectrum disorders (32%). Taken as a whole, AB seems to be more frequent in hyperkinetic movement disorders, notably those with stereotypies, and is influenced by anxiety, suggesting an involvement of the limbic part of the basal ganglia in its pathophysiology.

The Prevalence of TMD in Polish Young Adults

Abstract: Purpose The prevalence of temporomandibular disorders (TMD) in the general Polish population has not yet been thoroughly investigated. The aim of this study was to determine how frequently Polish young adults demonstrated the signs and symptoms of TMD, and how often they were aware of these. Materials and Methods The study involved 260 volunteers of approximately 18 years of age (and with an F:M ratio of 2.8), who had completed the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire in its internationally accepted Polish version. The volunteers were students from three randomly selected high schools in Krakow, Poland. Following the clinical examinations, all participants received none or one or more of the RDC/TMD axis I diagnoses on one or both sides: muscle disorders (group I), disk displacements (group II), arthralgia, osteoarthritis, and osteoarthrosis (group III). Classification on RDC/TMD axis II involved pain-related impairment (Graded Chronic Pain Severity, from 0: no TMD pain in the prior 6 months, to IV: high disability—severely limiting), depression, and somatization levels (normal, moderate, severe). Results On the RDC/TMD axis I, 69 (26.5%) of the participants received one or more of the possible diagnoses. Awareness of TMD was present in 20 (7.7%) people from that group, in the form of self-complaints. The difference between females and males was statistically significant (p = 0.0013). On the RDC/TMD axis II assessment, a diagnosis of pain, depression, or somatization was given in 38 (14.6%) cases from that group. Conclusion Muscle disorders were most frequently diagnosed in the group of Polish young adults, and the prevalence of the disease did not differ across similar groups of young people.

A Retrospective 2-Year Clinical Study of Immediate Prosthetic Rehabilitation of Edentulous Jaws with Four Implants and Prefabricated Bars.

Abstract: Purpose The purpose of this retrospective investigation was to evaluate the use of a prefabricated bar system for immediately loaded implants placed and restored according to the All-on-Four concept with up to 24-month follow-up. Materials and Methods A total of 51 patients (31 males and 20 females; mean age 63.4 years) presented with edentulous or partially edentulous jaws with severe atrophy of the posterior regions. All patients were treated with full-arch fixed prostheses (28 maxillary, 34 mandibular) each supported by four implants (two vertical, two distally tilted). The implants were immediately loaded with screw-retained full-arch restorations. Each prosthesis was supported by a prefabricated metal bar combined with high-density acrylic resin. Follow-up visits were scheduled at 6, 12, and 24 months after initial prosthetic loading. Intraoral radiographs were obtained immediately after surgery and at each follow-up visit by using a custom radiograph holder and parallel technique. Marginal bone levels were assessed using digital image analysis. Implant and prosthetic survival and success rates were evaluated. Patient satisfaction was further assessed using a 100-mm visual analog scale (VAS). Data were compared by means of the Mantel-Haenszel test. Results No drop-outs occurred. The overall implant survival rates were 100% and 98.38% for the vertical and tilted implants respectively. Two of the 62 definitive fixed prostheses were lost during the observation period due to implant failure. Since restoration replacement due to implant failure was not judged a prosthodontic failure according to the survival criteria provided in this study, the overall prosthetic survival rate was 100%. No statistically significant differences in marginal bone levels between vertical and tilted implants were detected at 24-month follow-up evaluation in either jaw. All participants were functionally and esthetically satisfied with their definitive restorations after 2 years functioning, as confirmed by the average VAS scores (masticatory function: 99.7; phonetic function: 99.5, esthetics: 99.2). Conclusions The preliminary 24-month results indicate that immediate loading of vertical and tilted implants using the evaluated prefabricated bar system may be a viable solution for edentulous jaw rehabilitation; however, more long-term prospective clinical trials are needed to affirm the effectiveness of this surgical-prosthetic protocol.

Fracture Resistance of Lithium Disilicate Ceramics Bonded to Enamel or Dentin Using Different Resin Cement Types and Film Thicknesses

Abstract: Purpose To investigate the influence of cement film thickness, cement type, and substrate (enamel or dentin) on ceramic fracture resistance. Materials and Methods One hundred extracted human third molars were polished to obtain 50 enamel and 50 dentin specimens. The specimens were cemented to 1-mm-thick lithium disilicate ceramic plates with different cement film thicknesses (100 and 300 μm) using metal strips as spacers. The cements used were etch-and-rinse (RelyX Ultimate) and self-adhesive (RelyX U200) resin cements. Compressive load was applied on the ceramic plates using a universal testing machine, and fracture loads were recorded in Newtons (N). Statistical analysis was performed by multiple regression (p < 0.05). Representative specimens were evaluated by scanning electron microscopy to control the cement film thickness. Results The RelyX Ultimate group with a cement thickness of 100 μm cemented to enamel showed the highest mean fracture load (MFL; 1591 ± 172.59 N). The RelyX Ultimate groups MFLs were significantly higher than the corresponding RelyX U200 groups (p < 0.05), and thinner film cement demonstrated a higher MFL than thicker films (p < 0.05). Bonding to dentin resulted in lower MFL than with enamel (p < 0.001). Conclusions Higher fracture loads were related to thinner cement film thickness and RelyX Ultimate resin cement. Bonding to dentin resulted in lower fracture loads than bonding to enamel. Clinical Significance Reduced resin film thickness could reduce lithium disilicate restoration fracture. Etch-and-rinse resin cements are recommended for cementing on either enamel or dentin, compared with self-adhesive resin cement, for improved fracture resistance.

Evaluation of Mandibular Movement Functions Using Instrumental Ultrasound System

Abstract: Purpose The article deals with routinely performed instrumental temporomandibular joint (TMJ) examinations and interpretation of findings obtained from the Arcus Digma ultrasound device in individuals with or without clinical symptoms of temporomandibular disorders (TMD). The aim of this study was to analyze mandibular movement functions and the relationship between incisors and condylar movement parameters during jaw opening, which may be helpful for clinical evaluation in these patients. Materials and methods The study group consisted of 84 young students with no dental problems and other serious acute or chronic diseases in the medical history; the students were examined both clinically and with the Arcus Digma ultrasound device. Results Helkimo Di = I was the most common score in 49 participants, and Helkimo Di = II in a significantly (p < 0.01, Di = I vs. Di = II) smaller number of participants. Medical history revealed symptoms of unilateral mastication in 15 participants and a statistically significant increased (p < 0.02, participants with symptoms of unilateral mastication vs. asymptomatic) condylar range of motion parameter during retrusion. Also a significant decrease (p < 0.03, participants with symptoms of unilateral mastication vs. asymptomatic) of the incisal and condylar ranges of motion during mouth opening was found. Limitation of mouth opening, defined as a decrease of inter-incisal distance, appeared in 19 participants (22.6%) and in 25 participants (29.8%) measured instrumentally with the Arcus Digma device. A comparison of instrumental result examinations of the right and left TMJs showed positive correlations of the range of mandible opening movement with the Posselt opening movement (r = 0.75) and opening/closing movements with the Posselt closing movements (r = 0.70). A correlation was demonstrated (r = 0.81) between the condylar range of motion studied on the left and on the right TMJ during mandible opening movement. Correlations were also found between opening-closing movements and the condylar range of motion of the left TMJ, and between the opening-closing movement and the condylar range of motion of the right TMJ during the opening movement. Conclusions According to the results of this study with instrumental Arcus Digma ultrasound device measurements of mandibular movements, data were provided on irregularities in TMJ function not detected in participants with or without clinical symptoms of TMD.

Interim Prosthesis Options for Dental Implants

Abstract: Dental implants have become a popular treatment modality for replacing missing teeth. In this regard, the importance of restoring patients with function during the implant healing period has grown in recent decades. Esthetic concerns, especially in the anterior region of the maxilla, should also be considered until the definitive restoration is delivered. Another indication for such restorations is maintenance of the space required for esthetic and functional definitive restorations in cases where the implant site is surrounded by natural teeth. Numerous articles have described different types of interim prostheses and their fabrication techniques. This article aims to briefly discuss all types of implant-related interim prostheses by different classification including provisional timing (before implant placement, after implant placement in unloading and loading periods), materials, and techniques used for making the restorations, the type of interim prosthesis retention, and definitive restoration. Furthermore, the abutment torque for such restorations and methods for transferring the soft tissue from interim to definitive prostheses are addressed.

In Vitro Wear Resistance of Nano-Hybrid Composite Denture Teeth.

Abstract: Purpose To evaluate the wear resistance of nano-hybrid composite denture teeth as compared to two commonly used denture teeth: interpenetrating polymer network (IPN) and double crosslinking polymethylmethacrylate (PMMA) denture teeth. Material and Methods 18 styli and 18 disk specimens were prepared from the three denture tooth materials: nano-hybrid composite, IPN, and double crosslinking PMMA. The specimens were mounted in a two-body wear testing machine to simulate chewing in the complete denture. The amount of wear from the styli specimens were measured before and after using a digital micrometer, and the depth of the wear track from the disk specimens was measured using a noncontact 3D optical profilometer. The total wear from each denture tooth group was compared using one-way ANOVA with a 0.05 significance level. A Tukey post hoc test was used to determine differences between the three groups. Results The mean total wear in the nano-hybrid composite teeth group was 1.16 mm, SD = 0.5 mm, statistically significantly higher (p ≤ 0.0001) than the IPN (mean = 0.13 mm, SD = 0.05) and double crosslinking PMMA tooth groups (mean = 0.31 mm, SD = 0.19). There was no statistically significant difference between IPN denture teeth and double crosslinking PMMA denture teeth in the amount of wear. Conclusions Nano-hybrid composite denture teeth exhibited statistically significantly more wear than the IPN and double crosslinking PMMA denture teeth.

Factors Influencing Removable Partial Denture Patient-Reported Outcomes of Quality of Life and Satisfaction: A Systematic Review.

Abstract: Purpose A systematic search of the literature was performed to identify and characterize articles reporting the influence of removable partial denture (RPD) therapy on satisfaction and quality of life (QoL). Materials and Methods The literature search for relevant articles published between January 1983 and March 30, 2013 was conducted using keyword searches of electronic databases and complimentary hand searches. The search strategy included the following keyword combinations (MeSH and free-text terms): fail, complication, surviv*, longevity, outcome, patient satisfaction or QoL, and denture or prosthes*, and partial and removable. Based on inclusion and exclusion criteria, articles focused on the effect of RPD therapy were reviewed and classified according to Strength-of-Recommendation Taxonomy (SORT) criteria. Results The combined search identified 997 publications; 198 duplicates were identified and removed, leaving 799 references for further evaluation. After abstract review, 209 articles were selected and read; 18 reports representing findings from 4002 patients were included. While two studies were prospective comparative investigations, the majority of studies represented cross-sectional and retrospective studies. Different instruments were used to measure oral health-quality of life (OHQoL) and satisfaction. Several investigations reported a significant association of satisfaction and QoL with either (a) age of the patient, (b) number of occluding dental units replaced, (c) replacement of anterior teeth, and (d) nature of the opposing arch. Conclusions A paucity of detailed investigations concerning outcomes of RPD therapy was noted. Improvement in OHQoL or satisfaction following provision of RPDs was not consistently reported. There is little evidence supporting any association between patient-reported QoL or satisfaction with technical or biological parameters of therapy. Therapeutic success of tooth replacement using RPDs should be carefully considered and compared with alternatives.

Effects of Simulated Gastric Juice on CAD/CAM Resin Composites—Morphological and Mechanical Evaluations

Abstract: Purpose To evaluate the effects of simulated gastric juice on CAD/CAM resin composites by means of morphological and mechanical (i.e., hardness) evaluations. Materials and Methods Fourteen specimens of each resin composite (Lava Ultimate and Paradigm MZ100) were prepared according to the manufacturer's instructions. They were submitted to erosive challenges in a simulated gastric juice (pH = 1.2) solution for 6 and 24 hours. Vickers microhardness and surface roughness (Ra, Rq) evaluations were taken before (baseline) and after acid exposure. Morphological analysis was obtained using scanning electron microscopy (SEM). Statistical analysis was performed using two-way repeated measures ANOVA and Student-Newman-Keuls's test (α = 0.05). Results Paradigm MZ100 demonstrated higher microhardness than Lava Ultimate regardless of the storage time period (p ≤ 0.001), and microhardness was not affected by the acidic challenge (p = 0.58). After 6 hours of acid exposure, a significant decrease in Ra and Rq was seen for Paradigm MZ100 when compared to the baseline (Ra p = 0.032; Rq p = 0.013); however, for Lava Ultimate only Rq decreased (p = 0.021), while Ra remained unchanged (p = 0.38). After 24 hours of acid exposure, while Paradigm MZ100 exhibited no additional changes in surface roughness (p ≥ 0.75), Lava Ultimate became rougher (Ra p = 0.041; Rq p = 0.014), as confirmed by SEM imaging. Conclusions The acidic scenario tested in the present study changed the surface roughness of the resin composites but not their Vickers microhardness. Moreover, both resin composites seem suitable for use under acidic scenarios, although Paradigm MZ100 showed enhanced stability compared to Lava Ultimate.

Effects of Hot Chemical Etching and 10-Metacryloxydecyl Dihydrogen Phosphate (MDP) Monomer on the Bond Strength of Zirconia Ceramics to Resin-Based Cements.

Abstract: Purpose The purpose of this in vitro study was to evaluate the hot chemical etching method on the shear bond strength between zirconia and two resin cements. Materials and Methods Sixty zirconia specimens (13 × 7.5 × 2.5 mm3) were prepared and treated as follows: (1) airborne-particle abrasion with 50 μm Al2O3 particles; (2) hot chemical etching for 10 minutes; (3) hot chemical etching for 30 minutes. Sixty composite cylinders of 3 mm diameter and height were prepared and bonded to zirconia specimens, which were divided into subgroups A and B. Group A: cemented with conventional resin cement (Variolink II); group B: cemented with 10-metacryloxydecyl dihydrogen phosphate (MDP) monomer containing resin cement (Panavia SA) after the application of surface treatments. Next, the specimens were stored in 37oC distilled water for 24 hours. Following water storage, shear bond strength test was performed at a 1 mm/min crosshead speed in a universal testing machine. The statistical analyses were performed with one-way ANOVA and post hoc Tukey tests. p < 0.05 was considered statistically significant. Results The results from all of the tested groups exhibited lower shear bond strength values than group II-B and higher shear bond strength values than group I-A (p < 0.05). Conclusion The use of the hot chemical etching method for 10 minutes increased the shear bond strength of zirconia ceramics to both conventional and resin cements and seems to be an effective method. The MDP monomer-containing resin cement, Panavia SA, improved the resin bonding of zirconia ceramics when combined with airborne-particle abrasion.

Strains Around Abutment Teeth with Different Attachments Used for Implant-Assisted Distal Extension Partial Overdentures: An In Vitro Study.

Abstract: Purpose The aim of this study was to evaluate and compare strain around abutment teeth with different attachments used for implant-assisted distal extension partial overdentures (IADEPODs) Materials and Methods A mandibular Kennedy class I acrylic model (remaining teeth from first premolar to first premolar) was constructed A conventional partial denture was constructed over the model (control, group 1) Two laboratory implants were then placed bilaterally in the first molar areas parallel to each other and perpendicular to the residual ridge Three additional experimental partial overdentures (PODs) were constructed and connected to the implants using ball (group 2), magnetic (group 3), and Locator (group 4) attachments Three linear strain gauges were bonded buccal, lingual, and distal to the first premolar abutment tooth at the right (loading) and the left (nonloading) sides For each group, a universal testing device was used to apply a unilateral vertical static load (50 N) on the first molar area, and the strain was recorded using a multichannel digital strainometer Results Significant differences between groups and between sites of strain gauges were detected Strains recorded for all groups were compressive (negative) in nature Group 1 demonstrated the highest strain, followed by group 3 and group 4; group 2 recorded the lowest strain For group 2, the highest strain was recoded at the lingual nonloading side For group 1, group 3, and group 4, the highest strain was recorded at the buccal loading side Conclusion Within the limitation of the present study, ball attachments used to retain IADEPODs to the implants were associated with lower strains around abutment teeth than Locator and magnetic attachments The highest strain was recorded with conventional partial dentures

In Vitro Effects of Plantago Major Extract, Aucubin, and Baicalein on Candida albicans Biofilm Formation, Metabolic Activity, and Cell Surface Hydrophobicity.

Abstract: Purpose To determine the in vitro effectiveness of Plantago major extract, along with two of its active components, aucubin and baicalein, on the inhibition of Candida albicans growth, biofilm formation, metabolic activity, and cell surface hydrophobicity. Materials and Methods Twofold dilutions of P. major, aucubin, and baicalein were used to determine the minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and the minimum biofilm inhibitory concentration (MBIC) of each solution. Separately, twofold dilutions of P. major, aucubin, and baicalein were used to determine the metabolic activity of established C. albicans biofilm using a 2,3-bis (2- methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-carboxanilide reduction assay. Twofold dilutions of P. major, aucubin, and baicalein were used to determine the cell surface hydrophobicity of treated C. albicans biofilm by a two-phase assay using hexadecane. The hydrophobicity percentage of the cell surface was then calculated. A mixed-model ANOVA test was used for intergroup comparisons. Results The MICs of P. major extract (diluted 1:2 to 1:8), aucubin (61 to 244 μg/ml), and baicalein (0.0063 to 100 μg/ml) on the total growth of C. albicans were noticeable at their highest concentrations, and the inhibition was dose dependent. The MFC was evaluated after 48 hours of incubation, and aucubin (244 μg/ml) exhibited a strong fungicidal activity at its highest concentration against C. albicans growth. The MBIC indicated no growth or reduced growth of C. albicans biofilm at the highest concentrations of aucubin (61 to 244 μg/ml) and baicalein (25 to 100 μg/ml). Similarly, the effects of these reagents on C. albicans biofilm metabolic activity and hydrophobicity demonstrated high effectiveness at their highest concentrations. Conclusion P. major extract, aucubin, and baicalein caused a dose-dependent reduction on the total growth, biofilm formation, metabolic activity, and cell surface hydrophobicity of C. albicans. This demonstrates their effectiveness as antifungals and suggests their promising potential use as solutions for C. albicans biofilm-related infections.

Fracture Resistance of Molar Crowns Fabricated with Monolithic All-Ceramic CAD/CAM Materials Cemented on Titanium Abutments: An In Vitro Study.

Abstract: Purpose To assess the fracture resistance of single-tooth implant-supported crown restorations made with different CAD/CAM blocks. Materials and Methods Thirty-six titanium abutments were put on dental implant analogs (Mis Implant). For each of three test groups (n = 12/group), implant-supported, cement-retained mandibular molar single crowns were produced. Crowns were made of lithium disilicate glass (LD) IPS e.max CAD, feldspathic glass ceramic (FEL) Vita Mark II, and resin nano-ceramic (RNC) Lava Ultimate. The crowns were cemented with self-adhesive resin cement RelyX Unicem 2. After chewing cycling, crowns were tested to failure in a universal testing machine. Fracture values were calculated as initial (F-initial) and maximum fracture (F-max). Results The study groups were ranked, in order of having highest value, (LD > FEL) > RNC for F-initial load value and (LD > RNC) > FEL for F-max load value. This demonstrated that there was no parallel change in the F-initial and F-max values presenting the fracture resistance of specimens. Conclusions There was no accordance between the F-initial and F-max values of the LD, RNC, and FEL after chewing simulation with thermocycling resembling 5 years of clinical functional use. LD had the highest fracture resistance during the fracture test. RNC had low fracture resistance; however, it had considerably high fracture resistance during the fracture test. FEL had considerably low fracture resistance values.

Effect of Aging Regimens on Resin Nanoceramic Chairside CAD/CAM Material.

Abstract: Purpose To evaluate the effect of cyclic mechanical loading, thermal cycling, and storage in water on a resin nanoceramic chairside computer-aided designed/computer-aided manufactured (CAD/CAM) material compared to a control leucite-reinforced glass-ceramic material. Materials and Methods One hundred twenty specimens (18 × 4 × 3 mm) were milled from two chairside CAD/CAM materials’ blocks (Lava Ultimate: LU; Vitablock Mark II: VM). Each group included four subgroups (A: n = 20 control; B: n = 20 cyclic loading [105 cycles, 80 N]; C: n = 20 thermal cycling [5 to 55°C]; D: n = 60 water storage [20: 3 months; 20: 6 months; 20: 9 months at 37°C]). Each subgroup included 10 specimens tested for flexure strength using three-point bending in a universal testing machine. The other 10 specimens were tested for surface roughness using an automated profiler followed by testing for surface hardness using a microhardness tester. Results LU displayed higher flexure strength than VM before and after all the aging conditions. The surface roughness for VM was lower than LU for the control, but both materials showed comparable values and significant increases after 9 months storage in water. After cyclic loading, only VM displayed a significant increase in the surface roughness value (p < 0.05). The surface hardness of VM was higher than LU for the control. VM did not show significant changes in hardness after any aging condition. LU showed significant reduction in surface hardness value only after storage in water (p < 0.05). Conclusion The resin nanoceramic Lava Ultimate can be used as a durable substitute for glass-ceramic chairside CAD/CAM material.

CAD/CAM-Assisted Auricular Prosthesis Fabrication for a Quick, Precise, and More Retentive Outcome: A Clinical Report.

Abstract: Auricular defects comprise a large proportion of maxillofacial deformities. Most patients with acquired deformities have psychosocial ineptness and seek cosmetic rehabilitation. Although minor defects can be corrected surgically, extensive deformities are difficult to reconstruct with plastic surgery. Contrary to that, prosthetic restoration can provide excellent esthetic results. The conventional methods of maxillofacial prosthesis fabrication are time consuming and the outcome depends on the technician's skill. The advent of CAD/CAM technology in the field of dentistry has brought enormous improvement in the quality of health care provided. In the past decade, several methods have been described employing CAD/CAM techniques for the cosmetic rehabilitation of auricular defects. This clinical report details the integration of multiple digital technologies of CT scanning, computer aided design, and rapid prototyping to construct an ear prosthesis with limited number of appointments.

Treatment Outcomes Based on Patients’ Self-Reported Measures after Receiving New Clasp or Precision Attachment-Retained Removable Partial Dentures

Abstract: Purpose To evaluate effects of a treatment taking into consideration esthetics, chewing, and oral health-related quality of life (OHRQoL) of two tooth replacement strategies for maxillary partially edentulous patients with clasp (C-RPD) and precision attachment (PA-RPD) retained removable partial dentures (RPD). Materials and Methods The study included 150 patients (72 men, 78 women) who received maxillary RPDs; 88 patients received clasp and 62 patients received precision attachment retained RPDs. Patients completed three questionnaires before treatment and again 3 months after treatment: the Orofacial Esthetic Scale (OES), the Oral Health Impact Profile (OHIP-14), and the Chewing Function Questionnaire (CFQ). Statistical analysis comprised descriptive statistics, paired t-test, and two-factor ANOVA. Results Both RPD treatments yielded better after-treatment summary scores when compared with the baseline scores (p < 0.01); however, better results were obtained in the PA-RPD group. Gender, as a single factor, did not yield significant effects; mutual interaction of retention type and gender yielded significant effects. The PA-RPD female group assessed esthetics, chewing function, and OHRQoL significantly better than males, and significantly worse than males in the C-RPD group. The covariate baseline scores yielded statistically significant effects; patients with worse pretreatment condition benefited more from both therapies. Conclusions Treatment outcomes were better in the PA-RPD group than the C-RPDs. Women showed greater concern for the treatment outcomes; their rates were significantly better than in male patients in the PA-RPD group; however, when their satisfaction was lower, their rates were significantly worse than in male patients (in the C-RPD group).

Efficiency of Cordless Versus Cord Techniques of Gingival Retraction: A Systematic Review.

Abstract: Purpose Primarily to assess the efficacy of cordless versus cord techniques in achieving hemostasis control and gingival displacement and their influence on gingival/periodontal health. In addition, subjective factors reported by the patient (pain, sensitivity, unpleasant taste, discomfort) and operator's experience to both techniques were analyzed. Materials and methods An electronic database search was conducted using five main databases ranging from publication year 1998 to December 2014 to identify any in vivo studies comparing cord and cordless gingival retraction techniques. Results Seven potential studies were analyzed. Out of the four articles that reported achievement of hemostasis control, three compared patients treated by an epi-gingival finish line and concluded that paste techniques were more efficient in controlling bleeding. Five studies reported on the amount of sulcus dilatation, with contrasting evidence. Only one study reported an increased gingival displacement when paste systems were used. Two studies did not observe any significant difference, although two showed greater gingival displacement associated with cords, particularly in cases where the finish line was placed at a subgingival level. Of the four studies that assessed the influence of both techniques on the gingival/periodontal health, three noted less traumatic injury to soft tissues when gingival paste was used. A paste system, in general, was documented to be more comfortable to patients and user-friendly to the operator. Conclusions Because of heterogeneity of measurement variables across studies, this study precluded a meta-analytic approach. Although both techniques (cord/cordless) are reliable in achieving gingival retraction, some situations were identified wherein each of the techniques proved to be more efficient.

Evaluation of Different Polishing Systems and Speeds for Dental Zirconia

Abstract: Purpose To evaluate two polishing systems and three polishing speeds on the gloss, roughness, and heat production of yttria stabilized tetragonal zirconia polycrystal (Y-TZP). Materials and Methods A Y-TZP block (Zenostar Zr Translucent) was sectioned into 4-mm-thick sections. Specimens (n = 30 per polishing system) were first wet ground with a fine diamond bur at 200,000 RPM for 15 seconds. The baseline gloss of all specimens was measured in a glossmeter (60° angle) in a direction perpendicular to grinding. Initial surface roughness (Ra) was determined on an optical profilometer in a direction perpendicular to grinding. The specimens were then polished with either a Dialite ZR Polishing Kit or a CeraMaster Polishing Kit. All grinding and polishing was performed by the same operator calibrated to apply approximately 2 N pressure. The medium grit polisher was used for 30 seconds, repeated for 30 seconds, and then the fine grit polisher was used. After each step, the gloss and roughness of each specimen was remeasured as described previously. Each polishing system was used at 5000, 15,000, and 40,000 RPM (n = 10 for each polish system/speed combination). A group of glazed specimens (n = 10) was evaluated for gloss and roughness as a control. The heat generated for each polishing step was measured with a thermocouple. The gloss and roughness of the specimens were analyzed using a linear mixed model and Tukey-Kramer post-hoc tests. Each step of polishing was compared to the glazed control group with an ANOVA and Dunnett's test. Results Polishing step, system, and speed were significant (p < 0.05) for gloss and roughness. Examination of system and step interaction was significant for gloss only. Post-hoc analysis revealed that 15,000 RPM produced higher gloss and lower roughness than other speeds. Each progressive step produced an improvement in gloss except for initial 30 seconds with the CeraMaster Coarse (medium polisher; p = 0.34). Roughness was also reduced at each progressive step. No polishing speed/system produced an increase in temperature above 41°C. Both polishing systems were capable of achieving a similar or superior roughness and gloss as the glazed control specimens after the final polishing step at 15,000 RPM. Conclusions Fifteen thousand RPM is an optimal polishing speed. Progressing through the polishing sequence significantly improves gloss and roughness and can create similar values as glazed zirconia.

Effect of Different Surface Treatments on Porcelain‐Resin Bond Strength

Abstract: Purpose The aim of this study was to evaluate the effects of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics Materials and Methods A total of 192 disk-shaped cores were prepared using two all-ceramic systems, of which 168 were submitted to SBS tests, and 24 were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) The ceramics used were IPS Empress emax (EX) lithium glass-ceramic and Vita In-Ceram Zirconia glass-infiltrated zirconia (ICZ) The specimens were randomly divided into seven groups (n = 12) on the basis of the surface treatment used: control; SB—sandblasting with 50 μm Al2O3 particles; CJ—chairside silica coating with 30 μm SiO2 particles and silanization (Clearfil Porcelain Bond Activator); HF—etching in 5% hydrofluoric acid and silanization; ER—etching with an Er:YAG laser (10 W); ND—Nd:YAG laser etching (08 W); and FS—etching with a femtosecond laser (860 mW) A luting cement (Clearfil Esthetic) was photopolymerized on each treated ceramic disk After subjecting the specimens to thermocycling (1000 cycles, 5°C to 55°C), SBS tests were performed using a universal testing machine The data were analyzed with two-way ANOVA and Tukey's tests using a significance limit of 5% Results Among the EX ceramics, the CJ (2910 MPa) and HF (2607 MPa) specimens had statistically higher SBS values For the ICZ ceramics, the highest value (2808 MPa) was obtained for the CJ specimens Conclusions Silanization after coating with silica improves the bond strengths of both EX and ICZ specimens, while HF etching is favorable only for the EX specimens

Cantilever Lengths and Anterior-Posterior Spreads of Interim, Acrylic Resin, Full-Arch Screw-Retained Prostheses and Their Relationship to Prosthetic Complications.

Abstract: Purpose To retrospectively record the distal cantilever lengths (CL) of full-arch interim, all-acrylic resin prostheses used in an immediate occlusal loading protocol. Anterior/posterior (A/P) spreads were measured on master casts associated with the interim prostheses. Ratios were calculated (CL/AP). Prosthetic complications were recorded. The ratios and prosthetic complications were statistically compared and analyzed for statistical and clinical significance. Materials and Methods One hundred twenty-eight patients with 192 edentulous arches (109 maxillary; 83 mandibular; 190 arches were restored with 4 implants; 2 maxillary arches were restored with 5 implants) were treated. Seven hundred seventy implants (Branemark System) from September 1, 2011, until August 31, 2013 were included in this report. Patients were treated and followed in a single private practice for up to 40 months. Implants had to have at least 35 Ncm of insertion torque to be immediately loaded. All implants were immediately loaded with full functional occlusions on the day the implants were placed. Interim, full-arch, all-acrylic resin prostheses were fabricated and placed into full functional occlusion following an All-on-Four protocol. Measurements of the distal cantilevered segments were made on the prostheses prior to insertion. A/P spreads were measured on the master casts made from abutment level impressions made on the day of surgery. Prosthetic complications (denture base fracture, cohesive/adhesive denture tooth fractures) were recorded in the charts as they occurred. All charts were reviewed for this report; no patients were lost to follow-up. Interim prosthetic repairs were analyzed by type (tooth or denture base), arch, gender, and location within the edentulous arches. Results One patient experienced complete maxillary implant failure; the overall implant survival rate (SR) was 99.5% (766 of 770). Four hundred thirty of 434 maxillary implants and 336 of 336 mandibular implants survived for SRs of 99.1 and 100%, respectively. Thirty four of the 192 interim prostheses (17.7%) warranted at least one repair during treatment. The average cantilevered segments for the interim maxillary prostheses without prosthetic complications were 9.7 mm (right) and 9.5 mm (left). The average cantilevered segments for the repaired maxillary prostheses were 10.1 mm (right); 9.9 mm (left). The average cantilevered segments for the interim mandibular prostheses without prosthetic complications were 9.2 mm (right) and 9.3 mm (left). The average cantilevered segments for the repaired mandibular prostheses were 9.87 mm (right) and 9.18 mm (left). The average maxillary A/P spread was 18.4 mm; the average mandibular A/P spread was 17.3 mm. The average maxillary CL/AP spread ratios were 0.55 (right) and 0.53 (left); the average mandibular CL/AP spread ratios were 0.61 (right) and 0.57 (left). There were no statistical correlations between the CL/AP ratios and the frequency or type of prosthetic repairs recorded in this study. The ratios were statistically significant (p = 0.041) for mandibular prostheses with prosthetic complications: slightly greater CL/A-P ratios were noted. Conclusions The results from this 2-year clinical retrospective analysis indicated that CL/AP ratios in the range of 0.5 to 0.6 generally resulted in successful interim prostheses during the time the interim prostheses were in function. The results of this investigation also revealed that 1 of 129 patients experienced implant failures; implants placed and restored on the same day with full-arch, screw-retained prostheses resulted in high clinical survival rates for implants and prostheses. The All-on-Four treatment protocol used in this study was a viable alternative to other implant loading/placement protocols for rehabilitating edentulous patients and resulted in minimal prosthetic complications.

Comparison of Maximum Intercuspal Contacts of Articulated Casts and Virtual Casts Requiring Posterior Fixed Partial Dentures.

Abstract: Purpose To evaluate the accuracy of the CEREC CAD/CAM system in reproducing the maximum intercuspal contacts of the casts, which include posterior teeth preparation for a fixed partial denture (FPD). Materials and Methods Ten pairs of gypsum casts were mounted in articulators in maximum intercuspal position (MIP) to serve as patient simulation models. Tooth #19 was removed from the cast. Occlusal contacts in MIP were identified with articulating paper, and digital impressions of the casts with unprepared teeth and buccal images in MIP were taken. Teeth #18 and #20 were prepared for an FPD, and full- and half-arch digital impressions of the casts with prepared teeth and buccal images from different sides were taken. In each situation, screenshot images of the virtual casts with occlusal contacts were saved as JPEG files. The proportions of congruence of virtual contacts with cast contacts were analyzed by superimposing screenshot images of the virtual casts onto the screenshot images of the casts with the indicated occlusal contacts in a transparent manner using an image-processing program. The data were statistically analyzed with a paired t-test. Results The highest percentages of virtually indicated contacts identical to the cast contacts were observed in non-prepared full-arch digital impressions. Comparison of full-arch impressions taken before and after tooth preparation showed no difference for congruence even if the buccal image was taken from the contralateral or ipsilateral side (p > 0.05). After tooth preparation, comparing full- and half-arch digital impressions revealed that half-arch impression showed significantly lower percentages of identical contacts (p 0.05). Conclusion When there is no posterior antagonist contact following tooth preparation for an FPD, taking a full-arch digital impression and designing the restoration on full-arch virtual models can be advocated.

Gingival Retraction Methods: A Systematic Review

Abstract: Purpose The aim of this systematic review was to assess the gingival retraction methods in terms of the amount of gingival retraction achieved and changes observed in various clinical parameters: gingival index (GI), plaque index (PI), probing depth (PD), and attachment loss (AL). Methods Data sources included three major databases, PubMed, CINAHL plus (Ebsco), and Cochrane, along with hand search. Search was made using the key terms in different permutations of gingival retraction* AND displacement method* OR technique* OR agents OR material* OR medicament*. Results The initial search results yielded 145 articles which were narrowed down to 10 articles using a strict eligibility criteria of including clinical trials or experimental studies on gingival retraction methods with the amount of tooth structure gained and assessment of clinical parameters as the outcomes conducted on human permanent teeth only. Gingival retraction was measured in 6/10 studies whereas the clinical parameters were assessed in 5/10 studies. Conclusions The total number of teeth assessed in the 10 included studies was 400. The most common method used for gingival retraction was chemomechanical. The results were heterogeneous with regards to the outcome variables. No method seemed to be significantly superior to the other in terms of gingival retraction achieved. Clinical parameters were not significantly affected by the gingival retraction method.

Heat Transfer and Thermal Stress Analysis of a Mandibular Molar Tooth Restored by Different Indirect Restorations Using a Three-Dimensional Finite Element Method.

Abstract: Purpose Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). Materials and Methods A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. Results The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4oC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. Conclusions The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42oC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations.

Marginal Gap of Milled versus Cast Gold Restorations.

Abstract: Purpose This in vitro study evaluated and compared the vertical marginal gap of cast and milled full coverage gold copings using two margin designs (chamfer and chamfer bevel) before and after fitting adjustments Materials and Methods Ten impressions were made of two metal master dies (one chamfer margin, one chamfer-bevel margin) and poured twice in Type IV stone The 20 subsequent casts with 40 dies were split into four groups (n = 10); cast gold bevel, cast gold chamfer, milled gold bevel, and milled gold chamfer groups The cast specimens received approximately 40 μm die relief no closer than 1 mm from the finish line Cast copings were hand waxed, cast in a high noble gold alloy, chemically divested, and the sprues were removed For milled gold copings, casts were scanned and copings designed using 3shape D900 scanner and software Parameters were set to approximate analog fabrication (cement gap = 001 mm; extra cement gap = 004 mm, drill radius = 065 mm) Copings were milled from the same high noble alloy All copings were seated on their respective master die in a custom scanning jig and measured using a measuring microscope at 90× (60 measurements per specimen, 15 per surface) Following initial measurements, all copings were adjusted on stone dies The number of adjustment cycles was recorded and post-adjustment measurements were made using the same method Data were analyzed using independent and paired t-tests Results Milled gold copings with a beveled margin (117 ± 204 μm) had a significantly (p < 005) smaller marginal gap than cast gold copings with a beveled margin (436 ± 468 μm) after adjustment Cast gold copings with a chamfer margin (227 ± 247 μm) had a significantly (p < 005) smaller marginal gap than milled gold copings with a chamfer margin (279 ± 316 μm) following adjustments Adjustments significantly decreased marginal gap for both cast groups (p < 005) and the milled chamfer bevel group (p < 005) but had no significant effect on the milled chamfer group Conclusions Within the limitations of this study, results indicate that gold restorations milled with the tested parameters provide a vertical marginal gap that is an acceptable alternative to traditional gold crown casting techniques

Crestal Bone Loss Around Adjacent Dental Implants Restored with Splinted and Nonsplinted Fixed Restorations: A Systematic Literature Review

Abstract: Purpose The aim of this systematic review was to compare the crestal bone loss around splinted and nonsplinted adjacent implants. Materials and Methods To address the focused question, “Is crestal bone loss around adjacent implants different with splinted from that with nonsplinted restorations?,” indexed databases were searched from 1965 up to and including May 2016 using various combinations of the following keywords: “implant,” “splinted,” “nonsplinted,” “unsplinted,” “connected,” “unconnected,” “nonconnected,” and “bone loss.” Letters to the editor, commentaries, historic reviews, case reports, case series, animal studies, and studies on full-arch rehabilitation were excluded. Results Six studies were included with titanium implants ranging from 114 to 1187 implants. All studies had nonsplinted and splinted restorations that ranged from 20 to 234 restorations and from 60 to 970 restorations, respectively. In all the studies, the follow-up period after the restoration placement ranged between 1 and 22 years, with a mean follow-up ranging between 3 and 10.18 ± 3.18 years. In all studies, the mean crestal bone loss for implants restored with nonsplinted restorations ranged between 0.30 ± 0.65 and 1.3 ± 0.2 mm, whereas the mean crestal bone loss for implants restored with splinted restorations ranged between 0.50 ± 0.8 and 1.22 ± 0.95 mm. Conclusion Within the limitations of this review it is concluded that adjacent implants restored with splinted and nonsplinted fixed restorations did not exhibit a difference in crestal bone loss. The evidence from this systematic review suggests further investigation.