The International Journal of Prosthodontics, 05/2022

The purpose of this study was to review the impact of loss of teeth and the current state of treatment options available for oral rehabilitation of edentulism. Function with complete dental prostheses varies based on a patient’s ability to adapt to removable prostheses and their psychologic acceptance of the treatment. There is varying dissatisfaction with removable prostheses, particularly in Western economies. This is driven in part by the availability of oral implants, which have transformed the treatment options for oral rehabilitation in general and for edentulous rehabilitation in particular. Quality-of-life studies have confirmed the advantages of implants for the retention and support of dental prostheses, as they improve function and esthetic measures to nearly those of the dentate state. Osseoperception, the concept of feedback to the sensorimotor system from tissues surrounding osseointegrated implants, contributes to enhanced function with implant treatment. It is recognized that tooth loss resulting in the loss of periodontal mechanoreceptors has a detrimental effect on jaw motor control even after implant treatment. However, despite this limitation, oral rehabilitation with or without implants, which improves function and esthetics, helps maintain psychosocial and cognitive health.

Purpose: To determine the association between clinical decision-making approaches and personal and professional background factors. Materials and Methods: An electronic questionnaire was sent to 550 dentists and dental students all over Saudi Arabia from October 2019 to January 2020. The questionnaire assessed personal and professional background factors in addition to three different clinical scenarios, and each participant was asked to rate the importance of some factors that might affect clinical decision-making on a visual analog scale (VAS). Multivariate analysis of variance (MANOVA) was performed to assess the association between the exposure variables (background and professional factors) and the outcome variables, which were the three clinical decision-making approaches (patient-related, clinical-case, and operator-related factors). Regression coefficients (B), 95% CI, and the adjusted R2 of the models were calculated. Results: A total of 420 participants responded to the questionnaire (76.36% response rate). Clinical-case factors had the highest mean scores, while the operator-related factors had the lowest mean scores. Men were significantly less likely than women to consider any factor decisive (P < .001). General dentists and specialists other than prosthodontists/restorative dentists assigned significantly lower importance to operatorrelated factors (P = .003) and clinical-case factors (P = .005). However, there was no statistically significant difference between undergraduate students and prosthodontists/restorative dentists in considering all decisive factors. Conclusion: Clinical-case factors were of greater importance compared to operator- and patient-related factors. General practitioners and specialists other than prosthodontists/restorative dentists gave lower attention to operator-related and clinical-case approaches, while experienced dentists showed greater importance to clinical-case and operator-related factors.

Purpose: To investigate the effect of missing teeth on patients’ oral health–related quality of life (OHRQoL). Materials and Methods: A total of 151 patients participated in this prospective bicenter clinical study (mean age: 64.7 ± 10.5 years; 71 women). Four subgroups were defined based on the number of missing teeth. OHRQoL was assessed using the German version of the Oral Health Impact Profile-49/53 (OHIP-G49/53) and visual analog scale (VAS) questionnaires. The effect of missing teeth on OHIP (total and dimension scores) and VAS scores before and after prosthetic treatment was investigated at baseline (T0), 1 week (T1), and 3 months (T2) after prosthetic treatment. Scores were analyzed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann- Whitney U tests. Correlations were assessed using Spearman ρ correlation. The level of significance was set at P = .05. Results: Initial OHIP and VAS scores were highest for patients with 11 to 28 missing teeth. Scores improved among all groups between T0 and T1/T2. After prosthetic rehabilitation (T1), improvements in total OHIP scores were greatest for patients with no missing teeth or with 11 to 28 missing teeth. Patients with no missing teeth or with 1 to 4 missing teeth before treatment had the lowest posttreatment OHIP scores. Total OHIP scores among the groups were in the same value range (P > .185). No direct correlation was found between the VAS and total OHIP scores. Conclusion: OHIP and VAS scores for OHRQoL were associated with the number of missing teeth. Prosthetic treatment resulted in improved OHRQoL and oral function among all groups. The use of a VAS yielded additional detailed information.

Purpose: To investigate the risk factors related to failure of removable partial dentures (RPDs) and to compare the survival of RPDs when abutment teeth have good vs reduced bone support. Materials and methods: In this longitudinal patient record-based cohort study with a mean follow-up of 44.9 months, Cox regression models were used to evaluate the associations between clinical covariates and abutment tooth failure, as well as prosthesis failure. Results: A total of 142 patients and 172 RPDs were included. Of the 172 prostheses, 64 (nearly 40%) failed after a mean time of about 4 years. Loss of abutment teeth was the main reason leading to RPD failure, followed closely by poor fit and adaptation. No factor was shown to be statistically significant at the prosthesis level. Women (Hazard Ratio [HR] = 0.542), endodontic treatment (HR = 3.460), presence of post and core (HR = 0.302), presence of a prosthetic crown (HR = 3.403), and abutment tooth type (in relation to incisor: canine HR = 0.196, premolar HR = 0.449) were the risk factors statistically significantly associated with the loss of abutment teeth. The pre-prosthesis amount of bone support of the teeth did not affect their prognosis as abutments for RPDs. Conclusion: RPD treatment modality presented a high failure rate after a mean follow-up of 4 years. Vital abutment teeth had a better survival rate than the ones treated endodontically (whether restored with or without a post and core); nevertheless, the amount of bone support did not affect their survival.

Purpose: To investigate the psychologic morbidities associated with tooth loss despite treatment with technically successful dentures. Materials and Methods: This cross-sectional questionnaire-based study compared the psychologic disturbance and functional difficulties in two groups: individuals with tooth loss who wore optimal-quality removable dentures (test group), and individuals with tooth loss who did not wear dentures (control group). The questionnaire used was developed and validated previously. The shortform revised Eysenck personality questionnaire was also used to assess the relationship with personality traits. A total of 138 participants were recruited (denture group = 70; control group = 68). Results: There was a significant difference in body image dissatisfaction between the groups (χ2 = 7.72, P value = .005). The denture group had 5.75-times higher probability than the control group of suffering from body image disturbance. Older patients were predicted to have 75% less probability of body image disturbance (OR = 0.25), and men were predicted to have up to 70% less disturbance (OR = 0.3). As for psychologic morbidities, participants in both groups presented with somatic symptoms related to depression or anxiety, which were nearly double that expected in the general population (15.7% and 7.8%, respectively). Furthermore, participants who complained about body image impairment were more likely to have higher scores on the neuroticism scale (OR = 3.64). Conclusion: Tooth loss and dentures could be associated with body image dissatisfaction and psychologic morbidity. Planning for patient-centered care is paramount prior to extracting any teeth and providing replacement options.

Purpose: To compare the changes in quality of life in edentulous patients with single implants supporting mandibular overdentures with two different attachment types before implant placement and after 6 and 24 months. Materials and methods: Eighty edentulous patients were recruited, and all patients completed the validated Oral Health Impact Profile (OHIP)-EDENT-19 questionnaire before implant surgery. A single implant was placed in the midline of the edentulous mandibles. All implants were allowed to heal for 3 months. After the healing period, randomization into one of two groups was accomplished using sealed envelopes: group A (ball attachment) and group B (locator attachment). The same questionnaire was completed 6 and 24 months postplacement. Mann-Whitney U test for independent samples was used to compare the two groups, while Freidman test was used for comparison within each group. Two-sided P values less than .05 were considered statistically significant. Results: There was an improvement in all domains of the OHIP-EDENT-19 scores at the 6- and 24-month follow-ups for both groups. The social disability domain showed a statistically significant improvement for group A at 6 and 24 months postplacement (P = .004, .005). Within group A, there was a statistically significant improvement within all seven domains (P = .001); while in group B, four domains (functional limitation, physical pain, psychosocial discomfort, and physical disability) and the total score (P = .001) showed a statistically significant improvement. Conclusion: Both attachments improved the patients' quality of life at 24 months postplacement. The ball attachment demonstrated a significant improvement regarding the social effects of the prostheses.

Purpose: To evaluate the accuracy of virtual static articulation and to determine factors that affect its accuracy. Materials and methods: An electronic search up to December 21, 2020 was carried out in the PubMed, Cochrane, and EMBASE databases, and further searching was performed in the references of the evaluated articles. Studies were included if they were published in a peer-reviewed journal in English, were a clinical or laboratory study assessing only static virtual articulation accuracy without making computer-aided manufacturing restorations, used intraoral scanner (IOS) or extraoral scanner (EOS) systems, and evaluated tooth or implant cases. Results: After applying the inclusion criteria, a total of 28 studies were analyzed. Nine were clinical, and 19 were laboratory. Most of the studies indicated that virtual static articulation had a comparable accuracy to conventional methods in the presence of completely dentate arches, stable occlusal contacts, a single prepared tooth, or arches involving a single missing posterior tooth. The factors that appeared to influence the accuracy were the articulation technique, number, dimension, and location of virtual interocclusal records (VIRs), the length of articulated scans, and the position and size of edentulous areas. Conclusion: Though conclusions were derived mainly from laboratory studies, static VIR had an acceptable accuracy in the presence of certain situations.

Purpose: To evaluate the accuracy and adaptation of BioHPP removable partial denture frameworks constructed from milling vs the pressing technique. Materials and Methods: This in vitro study was applied on an educational maxillary stone model with bilateral bounded saddles. Two different manufacturing techniques were used, and thus two groups were defined: (1) the pressed group, in which 20 BioHPP frameworks were constructed by milling a castable resin that was pressed into BioHPP using the lost wax technique; and (2) the milled group, in which 20 BioHPP frameworks were constructed directly by milling the BioHPP blanks. The accuracy of the frameworks was evaluated using Geomagic Control X software, and the gap distance was captured using a stereomicroscope. Results: The milled group showed higher values of accuracy than the pressed group in the x, y, and z axes, and according to Student t test, this difference was statistically significant in the x and z axes. Regarding the adaptation of the frameworks, the milled group showed lower adaptation values than the pressed group. Student t test showed that this difference was statistically significant regarding adaptation of the major connector. However, there was no statistically significant difference concerning adaptation of the denture bases between the two groups. Conclusion: Within the limitations of this study, it could be concluded that: (1) the milling technique could be used to fabricate BioHPP RPD frameworks with higher accuracy than the pressing technique; and (2) the pressing technique showed less gap distance (ie, better adaptation) at the area of the major connector.

Purpose: This study evaluated the effects of manipulator level (ML) on implant scan body (ISB) seating. It also investigated ISB vertical deviation with various levels of tightening torque. Materials and methods: In total, 10 standard acrylic resin models were prepared with the implant on the first molar site. ISBs were placed on the models by six operators with three MLs, manually and with a torque of 15 Ncm using an electronic torque driver. Digital scans were completed with an intraoral scan device. After superimposition in the software, ISB vertical deviation was compared between the 15 Ncm torque level and manual operation. One experienced operator then placed the ISB with different torque levels (20, 25, 30, and 35 Ncm) using an electronic torque driver. The ISB vertical deviation was also compared among torque levels. Vertical deviations within ML were analyzed using one-way analysis of variance (ANOVA). One-way repeated measures ANOVA was used to analyze the differences between torque levels (α = .05). Results: ISB vertical deviations differed among MLs (P < .01). Significant vertical deviations were observed between 20 and 30 Ncm (P < .01), 20 and 35 Ncm (P < .05), and 25 and 35 Ncm (P < .05). The largest estimated marginal mean was 13.5 ± 4.11 μm with a torque of 35 Ncm. Conclusion: Significant differences in ISB vertical deviation were observed according to MLs and tightening torque levels. The amounts of those deviations did not exceed the previously described occlusal threshold.

Purpose: The aim of this study was to evaluate the effects of two different home bleaching agents on color stability and surface roughness of hybrid ceramics. Materials and Methods: Three dental hybrid ceramics (Lava Ultimate, Cerasmart, and Vita Enamic) and two different home bleaching agents (9.5% hydrogen peroxide and 22% carbamide peroxide) were used. Thirty specimens of each material were prepared with dimensions of 12 × 14 × 1 mm. Technical polishing kits were applied to one surface of the specimens for the surface finishing procedure. Color parameters (L*a*b*) of the specimens were measured. Three subgroups were determined: control (C), hydrogen peroxide (HP), and carbamide peroxide (CP) (n = 10 each). After the bleaching procedures, color parameters were remeasured and color differences (ΔE) were calculated. Surface roughness values of the specimens were detected with a profilometer. Surface analysis of one specimen of each group was performed with a scanning electron microscope. Data were analyzed by two-way ANOVA and Tukey honest significant difference tests. Results: There was an interaction between material and bleaching agent type (P < .05). The highest ΔE values were observed in CP groups, and the lowest ΔE values were observed in control groups. For surface roughness, there was not an interaction between material and bleaching agent type (P >.05). Material and bleaching agent factors had a significant effect on surface roughness (P < .05). The highest surface roughness values were detected in HP groups. Conclusion: Home bleaching agents caused clinically acceptable color differences on hybrid ceramic materials. Hydrogen peroxide increased the surface roughness of hybrid ceramics. Int

Purpose: To assess the effect of tooth morphology on the amount of tooth structure removal and the effect of different assessment methods on the detected amount of removed tooth structure. Materials and Methods: Eight test groups (n = 10 each) of standardized artificial teeth were prepared for partial and full crowns. All teeth were prepared by the same operator following predefined preparation parameters. Tooth structure removal was measured by using three different assessment methods: digital volumetric analysis (DVA), weight analysis (WA), and combined computer-aided manufacture-weight analysis (CAMWA). Nonparametric repeated-measures ANOVA and post hoc analyses were used to determine the influence of tooth morphology and assessment method on the detected amount of tooth structure removal. Results: For partial-crown preparations, only tooth morphology had a significant impact on the detected amount of tooth structure removal (P < .0001), but not the different assessment methods used (P = .08); tooth structure removal was not significantly different between the canine and incisor groups, but was significant for all other groupwise comparisons. For full-crown preparations, the tooth morphology (P = .047) and different assessment methods (P = .01) had an impact on the detected tooth structure removal; however, only a few groupwise comparisons reached the significance level. Conclusion: The amount of tooth structure removal depended on tooth morphology and the type of assessment method, which should be taken into account when comparing results across studies. The detected amount of tooth structure removal was below the values described in the literature independent of the assessment method used.

Purpose: To compare the effect of thermomechanical aging on implant abutment color change when using different abutment backgrounds. Materials and Methods: In this study, three separate experimental groups (n = 10) with different implant abutment materials were used: zirconia, modified polyether ether ketone (MPEEK), and polyether ketone ketone (PEKK). Equal-sized glass-ceramic incisor crowns were cemented to the abutments using transparent dual-curing resin cement. The specimens were then subjected to the thermomechanical aging process for the clinical equivalent of 5 years of use. The color values of each specimen in the middle third and the incisal third were recorded by a digital spectrophotometer in the CIE L*a*b* color coordinates both before and after the aging process. Color differences between groups were compared using one-way analysis of variance (ANOVA), while Tukey test was used to compare differences within the groups (P = .05). Results: In terms of color change (ΔE00) values, the zirconia group was found to show statistically more color changes only in the middle third (P < .000), but there was no significant difference between the the MPEEK and PEKK groups. In all groups, the ΔE00 value was clinically acceptable (ΔE00 < 1.8). Conclusion: After the aging process, high-performance polymer abutments caused less color change than zirconia. Therefore, esthetically satisfying results can be obtained in the anterior region, especially when highly translucent crown materials are used.

Purpose: To compare the accuracy of dentists with different levels of expertise in computer-aided design (CAD) and prosthodontics to digitally design single crowns. Material and Methods: This in vitro study was conducted on 12 prepared teeth in 2 reference dental study models. The models were scanned using an intraoral scanner. Four dentists with different levels of clinical and CAD expertise (PROS: clinicians experienced in prosthodontics [n = 2]; CAD: experts in CAD [n = 2]) performed digital waxing on all prepared teeth using the same CAD software program. The resulting digital crown designs were compared to STL files of the original teeth to assess 3D deviations. The total cervical, distal, mesial, and occlusal surface deviations of the crowns from both groups were compared using paired t and Wilcoxon signed-rank tests (α = .05). Results: The total median 3D deviation was 0.10 mm (range: 0.03 to 0.61 mm) for the PROS group and 0.14 mm (range: 0.07 to 0.58 mm) for the CAD group. The PROS group presented significantly smaller total 3D (P = .021) and cervical margin (P = .001) deviations. There were no significant differences between groups on the distal, mesial, or occlusal surfaces (P > .05). The CAD group performed digital waxing significantly faster (P = .001). Conclusion: Within the limitations of this study, the present findings suggest that clinical experience has a higher impact on the accuracy of digital wax patterns of single crowns than CAD experience.

Purpose: To survey the clinical performance of telescopic-retained removable implant-supported dental prostheses (TR-RISDPs) in edentulous patients, as well as incidental maintenance measures and technical complications. Materials and Methods: In this retrospective analysis, the former presence of oral cancer, prosthesis location (maxilla or mandible), and participation in a follow-up program were analyzed as possible factors with an influence on survival and maintenance treatments of the TR-RISDPs and dental implants using Kaplan-Meier estimates. Results: A total of 86 TR-RISDPs (mean follow-up: 4.62 ± 3.24 years; maximum 13.8 years) and 465 implants (mean follow-up: 5.67 ± 3.59 years; maximum 16.5 years) were observed. Six (6.9%) of the TR-RISDPs had to be remade, and 11 (2.3%) implants failed. Regular attendance in the follow-up program showed significantly higher survival times and fewer maintenance treatments for the TRRISDPs (P < .05). Implants in patients with former oral cancer showed significantly lower survival times (P < .001). Conclusions: TR-RISDPs in edentulous patients show excellent clinical outcomes. Regular check-ups are decisive for success.

Purpose: To evaluate the fit and trueness of temporary crowns fabricated with 3D printing vs milling technologies and to analyze any existing correlations between fit and trueness. Materials and Methods: Marginal and internal fit and trueness were evaluated. Groups were compared using Kruskal-Wallis H test (α = .05), and correlations were analyzed using Spearman rank correlation analysis (α = .0016). Results: Intaglio surface trueness was partially correlated with the marginal and internal fit (P < .0016). Conclusion: High intaglio surface trueness in the axial and occlusal regions may result in poor marginal fit. In the axial region, high intaglio surface trueness may adversely affect both the marginal and internal fit.