The International Journal of Prosthodontics, 05/2017

Aims: Complete maxillary edentulism and prosthetic rehabilitation with removable full dentures are known to affect speech intelligibility. The aim of this study was to prospectively investigate the long-term effect of time on speech intelligibility in patients being rehabilitated with newly fabricated full maxillary dentures. Materials and Methods: Speech was recorded in a group of 14 patients (male = 9, female = 5; mean age ± standard deviation [SD] = 66.14 ± 7.03 years) five times within a mean period of 4 years (mean ± SD: 47.50 ± 18.16 months; minimum/maximum: 24/68 months) and in a control group of 40 persons with healthy dentition (male = 30, female = 10; mean age ± SD = 59 ± 12 years). All 14 participants had their inadequate removable full maxillary dentures replaced with newly fabricated dentures. Speech intelligibility was measured by means of a polyphone-based speech recognition system that automatically computed the percentage of accurately spoken words (word accuracy [WA]) at five different points in time: 1 week prior to prosthetic maxillary rehabilitation (both with and without inadequate dentures in situ) and at 1 week, 6 months, and a mean of 48 months after the insertion of newly fabricated full maxillary dentures. Results: Speech intelligibility of the patients significantly improved after 6 months of adaptation to the new removable full maxillary dentures (WA = 66.93% ± 9.21%) compared to inadequate dentures in situ (WA = 60.12% ± 10.48%). After this period, no further significant change in speech intelligibility was observed. After 1 week of adaptation, speech intelligibility of the rehabilitated patients aligned with that of the control group (WA = 69.79% ± 10.60%) and remained at this level during the examination period of 48 months. Conclusion: The provision of new removable full maxillary dentures can improve speech intelligibility to the level of a healthy control group on a long-term basis.

Purpose: The aim of this study was to test whether posterior zirconia-ceramic (ZC) and metalceramic (MC) fixed dental prostheses (FDPs) exhibit similar survival and technical/biologic complication rates. Materials and Methods: A total of 58 patients in need of 76 posterior FDPs were randomly assigned to receive 40 ZC and 36 MC FDPs. The restorations were examined at baseline (cementation) and yearly for 5 years. Technical and biologic outcomes were compared. The independent treatment groups were compared with nonparametric Mann-Whitney test for metric variables and with Fisher exact test for categoric data. Results: A total of 52 patients with 40 ZC and 29 MC FDPs were examined at 5 years. No FDP failed during the 5 years; 2 ZC FDPs failed at 65.4 and 73.3 months. Debonding occurred at 3 ZC FDPs. Technical outcomes (modified US Public Health Service criteria) and general periodontal parameters did not show significant differences between ZC and MC FDPs. Conclusion: ZC FDPs exhibited similar outcomes to MC FDPs based on 5-year survival estimates. The majority of technical and biologic outcome measures were not significantly different.

Purpose: The aim of this study was to investigate the oral health-related quality of life (OHRQoL) among subjects with typical, atypically positive, and atypically negative personality trait scores within the five basic dimensions of personality (neuroticism, extroversion, openness, agreeableness, and conscientiousness). Materials and Methods: A total of 235 subjects not seeking dental treatment were recruited from the families and acquaintances of dental students from the University of Salamanca. The 14-item Oral Health Impact Profile (OHIP-14) was used to capture the impact on their OHRQoL. The Neouroticism-Extroversion-Openness Personality Inventory Revised was applied to assess personality profiles. People were classified as having negatively atypical, typical, or positively atypical (PAP) personality, depending on whether the sum of the Z scores was < −1, between −1 and 1, or > 1, respectively. Pearson correlation, analysis of variance, and logistic regression test were used for the statistical analyses. Results: The sample was comprised of highly educated adults (aged 18-80 years) with good oral health habits. PAP subjects suffered significantly more in the dimension of psychologic discomfort (0.6 ± 0.7) than did their counterparts (0.3 ± 0.6), but the global impact in OHRQoL was comparable. Personality was weakly correlated with OHIP-14. The perception of dental treatment needs was found to be the major predictor of the impact on OHRQoL, but the number of negatively atypical deviated personality traits and the agreeableness raw score also had an effect. Conclusion: The risk of perceiving an impact on OHRQoL is significantly higher in individuals perceiving treatment needs and increases proportionally to the number of negatively atypical personality traits.

Bruxism is a common phenomenon, and emerging evidence suggests that biologic, psychologic, and exogenous factors have greater involvement than morphologic factors in its etiology. Diagnosis should adopt the grading system of possible, probable, and definite. In children, it could be a warning sign of certain psychologic disorders. The proposed mechanism for the bruxism-pain relationship at the individual level is that stress sensitivity and anxious personality traits may be responsible for bruxism activities that may lead to temporomandibular pain, which in turn is modulated by psychosocial factors. A multiple-P (plates, pep talk, psychology, pills) approach involving reversible treatments is recommended, and adult prosthodontic management should be based on a commonsense cautionary approach.

Purpose: The aim of this randomized clinical trial was to test the hypothesis that there are no statistically significant differences after 3 and 6 months in masticatory performance or chewing ability of people with new complete dentures made by an abbreviated or a conventional technique. Materials and Methods: The trial included 20 edentulous participants at a dental school in Brazil assigned randomly to receive dentures made by either a conventional technique involving six clinical sessions or by an abbreviated technique involving three clinical sessions. At baseline with old dentures and at 3 and 6 months with new dentures, masticatory performance was measured by counting the number of chewing strokes and the time before participants had an urge to swallow and by calculating the medium particle size of a silicone material after 20 chewing strokes and at the urge to swallow. On each occasion, the participants recorded on visual analog scales their ability to chew five food textures. Statistical significance (P ≤ .05) of changes in masticatory performance and chewing ability during the trial were analyzed with generalized estimating equations. Results: Both techniques improved masticatory performance between baseline and 6 months and the ability to bite and chew all foods apart from hard apples. Conclusion: There were no significant differences in masticatory performance or chewing ability after 6 months between complete dentures made by a conventional or an abbreviated technique.

Purpose: To assess the influence of several factors on the prevalence of dental implant failure, with special consideration of the placement of implants by different dental surgeons. Materials and Methods: This retrospective study is based on 2,670 patients who received 10,096 implants at one specialist clinic. Only the data of patients and implants treated by surgeons who had inserted a minimum of 200 implants at the clinic were included. Kaplan-Meier curves were stratified with respect to the individual surgeon. A generalized estimating equation (GEE) method was used to account for the fact that repeated observations (several implants) were placed in a single patient. The factors bone quantity, bone quality, implant location, implant surface, and implant system were analyzed with descriptive statistics separately for each individual surgeon. Results: A total of 10 surgeons were eligible. The differences between the survival curves of each individual were statistically significant. The multivariate GEE model showed the following variables to be statistically significant: surgeon, bruxism, intake of antidepressants, location, implant length, and implant system. The surgeon with the highest absolute number of failures was also the one who inserted the most implants in sites of poor bone and used turned implants in most cases, whereas the surgeon with the lowest absolute number of failures used mainly modern implants. Separate survival analyses of turned and modern implants stratified for the individual surgeon showed statistically significant differences in cumulative survival. Conclusion: Different levels of failure incidence could be observed between the surgeons, occasionally reaching significant levels. Although a direct causal relationship could not be ascertained, the results of the present study suggest that the surgeons' technique, skills, and/or judgment may negatively influence implant survival rates.

Purpose: The purpose of this study was to geometrically evaluate the effect of prosthetic rehabilitation on the facial appearance of mandibulectomy patients. Materials and Methods: Facial scans (with and without prostheses) were performed for 16 mandibulectomy patients using a noncontact three-dimensional (3D) digitizer, and 3D images were reconstructed with the corresponding software. The 3D datasets were geometrically evaluated and compared using 3D evaluation software. Results: The mean difference in absolute 3D deviations for full face scans was 382.2 μm. Conclusion: This method may be useful in evaluating the effect of conventional prostheses on the facial appearance of individuals with mandibulectomy defects.

Purpose: This retrospective study evaluated the survival rates of postendodontic severely decayed posterior permanent teeth in young adolescents. Materials and Methods: A total of 48 teeth (patient age range: 8.8-16.9 years) restored with a Kurer post-and-core system (Anchor System, Kurer K4) were assessed. Follow-up appointments 1 to 6 years posttreatment included radiographs and a clinical examination. Results: A total of 5 teeth (10.4%) were extracted, and 13 restorations (27%) required repair. Average restoration-to-failure time was 27 months (SD 12.2 months). Conclusion: In view of these findings, clinicians should consider post-and-core restorations an alternative to extractions of endodontically treated severely damaged teeth in adolescents.

Purpose: This clinical trial tested bilayered restorations based on ceria-stabilized tetragonal zirconia/alumina frameworks veneered with feldspathic ceramic. Materials and Methods: A total of 67 crowns and 40 fixed dental prostheses (FDPs) were luted in 57 patients with self-etching/self-adhesive composite resin cement. Dental status and integrity of restorations were evaluated at 2 weeks, 6 months, and then annually. Results: A total of 66 crowns and 36 FDPs (88% posterior) survived for success rates of 93.4% for crowns and 89% for FDPs at 2 years. In particular, 11 cohesive ceramic chippings were observed in 5 crowns and 6 FDPs. Conclusion: The material allows excellent marginal adaptation. Susceptibility to veneering failures might be due to framework design and the necessities of esthetics.

Purpose: The aim of this study was to analyze the associations between missing teeth, occlusal support, and temporomandibular disorders (TMD) among elderly Vietnamese. Materials and Methods: The study consisted of 145 TMD and 112 non-TMD (control group) participants aged 65 to 74 years. TMD was evaluated using Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I. An occlusal unit (OU) was defined as the cusp of a tooth coupled with the fossa of its antagonist tooth. A premolar pair was counted as one OU and a molar pair as two OUs. Dentition was divided into four occlusal support zones (OSZs) based on occluding pairs of posterior teeth by using Eichner classification: Class A had 4 OSZs, Class B had 1 to 3 OSZs or only anterior teeth, and Class C had no OSZ. Results: The TMD group lost significantly more posterior teeth (mean ± SD 5.1 ± 4.7) than the control group (4.0 ± 3.9, P = .033). The mean ± SD OUs of the TMD and control groups were 5.1 ± 4.6 and 6.0 ± 4.3, respectively, which was nonsignificant (NS). The distribution of Class A (40.7%), Class B (40.0%), and Class C (19.3%) among the TMD group was not significantly different from the control group (50.0%, 38.4%, and 11.6%, respectively, NS). The odds of having TMD were positively associated with total unilateral loss of OUs (OR = 3.4, 95% CI = 1.2-9.4, P = .020) and total bilateral loss of OUs (OR = 2.7, 95% CI = 1.2-6.6, P = .027). Conclusion: Total loss of OSZs on one or both sides of the mouth were found to be predictors of TMD among elderly Vietnamese.

Purpose: Provisional restorations exhibit various degrees of microleakage when cemented. Incorporation of quaternized polyethyleneimine nanoparticles (QPEI) into provisional cements may be effective against bacteria in vivo. Materials and Methods: Nine polymethylmethacrylate provisional restorations in human volunteers were evaluated after cementation with and without QPEI nanoparticles. Bacterial load in the provisional cement was assessed after 1 week of cementation. Results: The number of colonyforming units in the cement with QPEI was significantly lower (P < .05) than in the control cement. Conclusion: The results of this in vivo study clearly indicate that provisional cement incorporating QPEI nanoparticles significantly reduces viable bacterial counts in the provisional cement in all patients.

Purpose: The aim of this article was to critically review the current application of additive manufacturing (AM)/3D-printing techniques in prosthodontics and to highlight the influence of various technical factors involved in different AM technologies. Materials and Methods: A standard approach of searching MEDLINE, EMBASE, and Google Scholar databases was followed. The following search terms were used: (Prosth* OR Restoration) AND (Prototype OR Additive Manufacture* OR Compute* OR 3D-print* OR CAD/CAM) AND (Dentistry OR Dental). Hand searching the reference lists of the included articles and personal connections revealed additional relevant articles. Selection criteria were any article written in English and reporting on the application of AM in prosthodontics from 1990 to February 2016. Results: From a total of 4,290 articles identified, 33 were seen as relevant. Of these, 3 were narrative reviews, 18 were in vitro studies, and 12 were clinical in vivo studies. Different AM technologies are applied in prosthodontics, directly and indirectly, for the fabrication of fixed metal copings, metal frameworks for removable partial dentures, and plastic mock-ups and resin patterns for further conventional metal castings. Technical factors involved in different AM techniques influence the overall quality, the mechanical properties of the printed parts, and the total cost and manufacturing time. Conclusion: AM is promising and offers new possibilities in the field of prosthodontics, though its application is still limited. An understanding of these limitations and of developments in material science is crucial prior to considering AM as an acceptable method for the fabrication of dental prostheses.

Purpose: The aim of this study was to compare the shear bond strength of crowns cemented on natural teeth after surface treatment of the enamel with an erbium-doped yttrium aluminum garnet (Er:YAG) laser. Materials and Methods: Crown preparation was done for 40 full-metal crowns, and wax patterns with loops were cast in a cobalt-chromium alloy. The Er:YAG laser was used for surface treatment of some teeth, and teeth without surface treatment acted as the control. Glass-ionomer and self-adhesive resin luting cements were used for cementation. Shear bond strength was tested using a universal testing machine, and statistical analysis was done using paired t test. Scanning electron microscopy analysis was also carried out to study alterations of the enamel and dentin surfaces. Results: Significant increase in shear strength was noted after laser etching the teeth with Er:YAG laser for both types of cement (P < .0001). Conclusion: The results showed that surface treatment using an Er:YAG laser resulted in significant increase in retention of crowns.

Purpose: To describe a method for customizing scuba diving mouthpieces, to examine their usability, and to assess divers' satisfaction with their use. Materials and Methods: A rational method for fabricating custom-made mouthpieces for scuba diving was developed. Twenty scuba divers agreed to use a custom-made mouthpiece for at least 4 weeks. After mouthpiece use, participants completed an 11-item questionnaire. Results: Custom-made mouthpieces had significantly lower scores for all items on the questionnaire except uncomfortable sensation, indicating that they were more comfortable than ready-made mouthpieces. Conclusion: It can be concluded that these novel custom-made mouthpieces for scuba diving offer greater comfort than ready-made mouthpieces.

Logical categorization of implant-supported fixed partial dentures (ISFPDs) based on implant angulation, abutment type, and screw access channel (SAC) design for screw-retained restoration is not available in the literature. This article proposes a simple classification system to describe implant angulations and prosthesis design affecting abutment selection (engaging or nonengaging) for ISFPDs. An additional classification that addresses screw access channel designs is also introduced. These classifications provide clear interpretation of clinical scenarios for ISFPD design consideration and a basis for categorization of future complications. The angulation-based and prosthetic-based classifications simplify communication regarding implant angulation and prosthesis design type for ISFPDs. The SAC classification assists in prosthetic design, factoring in function and esthetics when designing the screw access.

Purpose: This paper describes a new ultrasonic instrument (tipholder DB1 with crown prep tip inserts) designed to optimize prosthodontic margin repositioning and finishing. Materials and Methods: The insert movement was assessed, and it was demonstrated that tipholder DB1 provides its inserts with an elliptical-like movement, making the entire insert surface able to cut. Then, 20 extracted teeth were prepared using tipholder DB1, sonic instruments, and traditional drills. Dental surface roughness produced using each of the three tools was measured using a roughness tester. Results were compared using univariate analysis of variance and Bonferroni post hoc test. Results: The roughness produced using tipholder DB1 with crown prep insert presented no statistically significant differences compared to the roughness produced using sonic instruments and traditional drills. Conclusion: Tipholder DB1 with crown prep inserts is a promising treatment for margin repositioning and finishing.