The International Journal of Prosthodontics, 05/2024

Purpose: To investigate temporomandibular disorder (TMD) prevalence as well as potential TMD risk factors among postgraduate students. Materials and Methods: In this cross-sectional and correlation study, 1,255 postgraduate students from different universities were recruited to answer Fonseca’s Anamnestic Index (FAI) in addition to collected demographic data and relevant dental history. FAI was used to classify TMD severity. Of the 1,255 participants included, 593 had previous clinical/radiographic TMD reports. Chi-square and Fisher exact tests investigated the relation between each predictor and TMD at P ≤ .05. A logistic binary regression analysis examined the model fit using -2Log likelihood and Pseudo R2 tests at P ≤ .05. Results: Based on previous clinical/radiographic reports and FAI, 73.4% of the participants had TMDs, of whom 57% had mild dysfunction, followed by moderate (31.7%) and severe (11.3%). There was a statistically significant association between sex, depression, lip/object biting, and clenching with TMDs (P < .001), where women were 2.302 times more likely to develop TMDs than men. The combination of lip biting and clenching in women dramatically increased the risk of TMDs (-2Log Likelihood = 385.7, P < .001 and a Cox and Snell value = 0.315 and a Nagelkerke value = 0.395). Conclusions: TMDs seem to be highly prevalent among postgraduate students in Egypt, and female postgraduate students who bite their lips or grind their teeth are particularly highly prone to the condition. Object biting and depression could also be considered risk factors.

Purpose: To compare occlusal schemes with condylar inclination and anterior guidance in dentate individuals. Materials and Methods: A total of 26 dentate patients of Indian origin between the ages of 18 and 30 with canine-guided occlusion and 26 patients with group function occlusion were included in the study. The School of Articulator Munich (SAM) Axioquick system was used to assess the condylar guidance and eccentric tracings of the patients. For analyses, Student t test was used. For quantitative data, the means and SDs were calculated. For statistical analyses, the probability of type-I error of .05 was considered statistically significant. Results: The mean condylar guidance for canine-guided and group function occlusion was 38.4 ± 12.7 degrees and 30.5 ± 12.5 degrees on the right side, respectively. On the left side it was 36.5 ± 13.0 degrees and 27.5 ± 12.0 degrees for canine-guided and group function occlusion, respectively, with a statistically significant difference (P = .01). The condylar guidance, incisal guidance, Bennett angle, protrusion, left lateral and right lateral movement, and left and right lateral angles were analyzed statistically between the two types of occlusions. The results showed a statistically significant difference between the two groups for all parameters except right condylar guidance. Furthermore, all parameters were higher in the canine-guided occlusion group over group function occlusion. Conclusions: Within the study limitations, it was concluded that the condylar guidance was steeper in canine-guided occlusion than in group function occlusion. The eccentric parameters were steeper in canine-guided occlusion than in group function occlusion. This study showcases that the condylar guidance might not play a major role in determining the occlusal scheme but that the incisal guidance determines the occlusal scheme predominantly in Class 1 occlusion patients. Keywords: Anterior Guidance; Condylar Guidance; Bennett Angle; Axioquick

Purpose: To identify the prevalence of and factors associated with total edentulism in the older Brazilian population and to verify whether edentulism influences self-perception of oral health and difficulty in eating. Materials and Methods: This cross-sectional, population-based study used the database of the National Health Survey conducted in Brazil. Chi-square test was initially used for data analysis. Subsequently, a multivariate analysis of Poisson multiple regression type was performed to verify the adjusted prevalence ratios. Results: A total of 43,554 older adults participated in the study, of whom 32% had completely lost their teeth. This total edentulism, based on the multivariate analysis, was associated with female gender, advanced age, illiteracy, smoking, and lack of health insurance or dental insurance (P < .001 for all). Total edentulism had an impact on better self-perception of oral health (P < .001) and greater difficulties in eating (P = .001). Conclusions: Total edentulism in older adults is associated with worse socioeconomic conditions and a worse lifestyle. This condition has a negative impact on diet and positively affects self-perception of oral health. Keywords: Edentulism; seniors; prevalence.

Purpose: To investigate the psychosocial and behavioral impact of oligodontia across three presentation types and determine if presentation type can infer impact. Materials and Methods: Thirty patients who had been diagnosed and treated for oligodontia between 2006 and 2021 were identified from hospital records. Patients received two questionnaires: (1) a modified version of a condition-specific questionnaire— the Cleft Research Questionnaire (CRQ), used to investigate demographic, life, and treatment details and impacts—and (2) the Oral Health Impact Profile (OHIP-14), used to investigate the oral health–related quality of life. Patients were assigned to three presentations (Types 1 to 3) of oligodontia, identified according to the edentulous space present and complexity of prosthodontic treatment required. The hypothesis that there is a relationship between oligodontia type and study variables was tested. Results: Twenty-two questionnaires were completed and returned. There were 13 men and 9 women. The age range was from 16 to 32 years. In total, 18 patients had nonsyndromic oligodontia and 4 had oligodontia associated with anhidrotic ectodermal dysplasia (AED). The main areas of impact were patient-reported: life less satisfying (64.5%, n = 14; pretreatment), making friends (45%, n = 10), school participation (45%, n = 10), and public speaking (45%, n = 10). No relationship was discovered between the degree of physical effect of the presentation type and study variables, including the degree of psychosocial impact or life satisfaction. Conclusions: Oligodontia can have a negative functional and social impact on a patient prior to prosthodontic treatment. Prosthodontic treatment improved the life satisfaction for most patients. Psychosocial outcomes could not be inferred by the presentation type of oligodontia.

Purpose: To evaluate the distortion probability in impressions of completely dentate arches when different impression materials are used in relation to operator experience. Materials and Methods: A total of 28 students (Group A) and 7 dentists (Group B) performed three maxillary impressions on 28 participants, each using vinyl siloxane ether (VSE), polyether (PE), and irreversible hydrocolloid (IHC). Gypsum master casts were fabricated and subsequently digitized. Intraoral scans were taken as a control. Differences between master casts and intraoral scans were visualized with heatmaps, and planar deviations were investigated. If planar deviations > 120 μm were found, the impression was rated as “distorted.” An additional superimposition using the casts from VSE or PE was performed to confirm the presence of distortions. The relative number of surfaces with distortions in each impression was calculated. The procedure was repeated for a distortion threshold of 500 μm. The statistical analyses included repeated measures ANOVA (RMA) and post hoc tests (α < .05). Results: When 120 μm was considered as the threshold for distortions, IHC impressions showed higher distortion probability than PE impressions in Group A (P = .003) and Group B (P < .0001). In Group B, PE showed a lower distortion probability than VSE (P = .02). There was no significant difference between the study groups (P = .42). Considering 500 μm as a threshold for distortions, there was no difference between impression materials (P = .17) or study groups (P = .53). Conclusions: There were no statistically significant differences in relation to operator experience. Different impression materials had a significant impact on distortion probability. PE impressions showed the lowest distortion probability.

Purpose: To determine whether food texture affects chewing side preference (CSP) and to investigate the relationship between CSP and masticatory factors, such as occlusal contact area, bite force, and masticatory performance. Materials and Methods: Forty-seven adults (20 women and 27 men; mean age: 24 years) participated in this study. Three types of food (chewing gum, beef jerky, and peanuts) were provided to assess CSP. Occlusal contact area was measured at various ranges of interocclusal distance, and the bite force was measured. Masticatory performance was assessed according to the median particle size. Asymmetry indices of each measurement were calculated and analyzed using Pearson correlation coefficient (α = .05). Results: The CSP for beef jerky and peanuts were significantly correlated with each other, whereas the CSP for chewing gum was not correlated with other food. The proportion of participants who chewed equally on both sides was higher for chewing gum than for beef jerky. There was a significant correlation between the CSP for beef jerky and occlusal contact area, especially at interocclusal distance ranges of 0 to 89 μm and 0 to 109 μm (r = 0.41). Bite force and masticatory performance were not significantly correlated with CSP. Conclusions: Food texture seemed to affect CSP, and masticatory laterality was greater for tough foods. Moreover, CSP for tough food was closely related to the occlusal contact area at an interocclusal distance level of about 0.1 mm.

Purpose: To compare the masking ability of monolithic CAD/CAM veneers placed over different resin cement shades and substrate colors. Materials and Methods: Veneers were milled from four different monolithic CAD/CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconiareinforced lithium silicate ceramic (VS), and high-translucency zirconia ceramic (YZ-XT). Veneers were luted on natural tooth-colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (opaque white or translucent). Each CAD/CAM material, resin cement shade, and substrate combination comprised 9 sample veneers (N = 216). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (ΔE₀₀) were calculated using CIEDE2000 formula and compared to perceptibility (P = .81 ΔE₀₀ units) and acceptability (AT = 1.77 ΔE₀₀ units) visual thresholds. Color variation data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (α = .05). Results: The highest ΔE₀₀ value was obtained in the VMII group placed over a discolored substrate, followed by the Emax CAD, YZ-XT, and VS groups. The effect of material types on ΔE₀₀ values was significantly observed when the veneers were luted on discolored substrates using translucent resin cement (P < .05). Conclusions: Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD/CAM laminate veneers.

Purpose: To compare the color dimensions, color discrepancies (ΔE₀₀), and surface roughness of milled materials before and after application of a bleaching agent. Materials and Methods: A total of 10 extracted molars were obtained. Each tooth was cut in transverse sections to create disks (3-mm thick, 10-mm diameter; control group). Disk specimens of eight materials (n = 10 per group) were fabricated: polymethyl methacrylate (PMMA) interim material (PMMA-Telio group), two resin nanoceramics (RNC-Ultimate group and RNC-Cerasmart group), two hybrid ceramics (HC-Shofu group and HC-Enamic group), lithium disilicate (LD-Emax group), zirconia-reinforced glass ceramic (ZGC-Suprinity group), and zirconia (Zr-InCeram group). Color measurements were obtained using a spectrophotometer before and after applying 35% hydrogen peroxide–based bleaching agent. Pre- and postbleaching surface roughness (Sa) analyses were completed using a profilometer. Results: Significant L*, a*, b*, and ΔE₀₀ value differences were found (P < .05). Color discrepancies (ΔE₀₀) ranged from 0.30 ± 0.14 to 4.82 ± 0.10. The highest color discrepancies were measured on the PMMA-Telio group, while the lowest color discrepancies were computed for ZGC-Suprinity, RNCUltimate, and RNC-Cerasmart. Significant surface roughness differences were found (P < .05). The largest increase of surface roughness values between the pre- and postbleaching measurements was obtained in the PMMA-Telio group with a mean ΔSa value of 4.73 ± 3.02, while the largest decrease of surface roughness values between the pre- and postbleaching measurements was obtained in the Zr-InCeram group with a mean ΔSa value of –1.58 ± 0.10. Conclusions: The milled materials showed significant pre- and postbleaching color and surface roughness discrepancies.

Purpose: To compare the translucency parameters and masking abilities of different monolithic CAD/CAM ceramics placed on different-colored substructures. Materials and Methods: Square-shaped specimens (12 × 12 × 1.5 mm) were prepared from feldspathic (C), leucite (EMP), lithium disilicate (e.max), zirconiareinforced lithium silicate (VS), resin nanoceramic (LU), polymer-infiltrated ceramic (VE), hybrid nanoceramic (GC), monolithic zirconia (TZI), and composite resin (TC) blocks (n = 10 per material). After mechanical polishing, the translucency parameter (TP) was calculated. Then, each ceramic specimen was measured on eight substructures, and the color difference between ND2 and each substrate was calculated with the CIEDE2000 formula. TP values were analyzed with one-way ANOVA and Games-Howell tests, and the color differences indicating masking ability were analyzed with two-way ANOVA and Tukey HSD tests. Results: The highest TP was observed in TC, followed by LU, EMP, C,GC, e.max, VS, VE, and TZI. The ΔE₀₀ color difference values of TZI, VS, and VE on all abutment colors, except for ND9, were below the acceptable threshold value. Conclusions: All monolithic ceramic materials used in the study masked the ND1 and ND3 substrates. The ND9, representing severely discolored or devitalized preparations, could not be masked by any monolithic CAD/CAM ceramics used in the study.

Purpose: To review the literature on CAD/CAM removable complete and partial dentures regarding patient- and clinician-reported outcomes. Materials and Methods: We performed an electronic search of the Cochrane Central Register of controlled trials (CENTRAL), MEDLINE (Ovid), EMBASE, Scopus, and Web of Science databases (last update: March 2023). All clinical trials or observational studies investigating CAD/ CAM removable dentures (conventional or implant-retained) were included. Results: The search yielded 4,035 records and led to 58 included studies. Results suggest that CAD/CAM complete and partial dentures, when compared to the conventional ones, can save time and resources while being rated either noninferior or superior by patients and clinicians in most studies. However, consensus on which workflow offers fewer adjustments and postoperative sessions is still pending. Conclusions: The literature suggests that CAD/CAM complete and partial dentures can combine substantial time and cost savings, with patient and clinician experiences at least comparable to conventional prostheses. Given the low evidence level of existing studies, future well-designed randomized trials with large sample sizes are required to confirm those advantages. Keywords: Removable denture, CAD/CAM, Patient-reported outcomes, Clinical outcome

Purpose: To evaluate the accuracy of complete-arch digital implant impressions using different intraoral scan body (ISB) materials and intraoral scanners (IOSs). Materials and Methods: The mandibular dental cast of an edentulous patient with six tissue-level dental implants was used as the master cast. Two types of ISBs—polyether ether ketone (PEEK) and plasma-coated medical titanium—were used with five IOSs: TRIOS 4 (T4), Virtuo Vivo (VV), Medit i700 (Mi700), iTero 5D (i5D), and Primescan (PS). To assess accuracy, digital impressions (n = 10) with each IOS and ISB were compared to two reference models obtained by digitizing the master cast with each ISB type using a desktop scanner (IScan4D LS3i) and importing the scan data into metrology software (Geomagic Control X). Root mean square (RMS) error was employed to evaluate overall deviation values (trueness), while precision was determined using the SD of RMS values. Statistical significance was set at P < .05. Kruskal-Wallis test was used, followed by the pairwise comparison method with Bonferroni correction (α = .05). Results: An interaction between ISB material and IOS was found (P = .001). Plasma-coated medical titanium ISBs demonstrated significantly higher trueness and precision compared to PEEK ISBs with T4 (P = .001), Mi700 (P = .001; P = .004), and i5D (P = .001). Conversely, VV exhibited higher trueness and precision values with PEEK ISBs (P = .005; P = .003). PS provided the highest trueness and precision regardless of the ISB material (P = .912). T4 showed the lowest accuracy for PEEK ISBs, and VV showed the lowest accuracy for plasma-coated medical titanium ISBs. Conclusions: Except for PS, all IOSs showed significant differences between ISB materials. PS demonstrated the highest accuracy with both ISB materials, whereas T4 had the lowest accuracy for PEEK ISBs, and VV showed the lowest accuracy for plasma-coated medical titanium ISBs.

Treatment of acute cases of amelogenesis imperfecta (AI) is challenging in children due to the absence of a consensus statement on therapeutic recommendations. This article presents the effectiveness of an interdisciplinary approach—including orthodontics, orthognathic surgery, and prosthodontics using digital technology—in a child with AI and skeletal deformities. The early management over a 6-year period had a very positive impact on the quality of life related to oral health. The full-mouth rehabilitation in adulthood with all-ceramic crowns showed a fully satisfactory result after 60 months of follow-up. Keywords: Amelogenesis imperfecta; Full-mouth rehabilitation; CAD-CAM; Orthognatic surgery; Case report

Purpose: To investigate the effect of irradiation time and zirconia thickness using low power Er,Cr:YSGG laser irradia)on (for debonding purposes) on the thermal changes and shear bond strength (SBS) of resin-bonded 3% mol yIrium oxide stabilized tetragonal zirconia polycrystal (3YTZP) specimens. Materials and Methods: 3Y-TZP slices of 0.5-, 2-, and 3- mm thick were used. The temperatures during laser irradiation using single spot irradiation at different times (30 seconds, 60 seconds, 90 seconds, and 120 seconds) and line scanning irradiation from one spot to another at three different distances (2, 4, and 6 mm) were recorded. Single spot and line scanning irradiation data were analyzed using three-way ANOVA (α = .05) and generalized linear mixed model, respectively. Nonirradiated (control) and irradiated resin-bonded 3Y-TZP specimens were shear tested, and the data were analyzed using two-way ANOVA (α = .05). Results: Under single spot irradiation, the laser-induced temperature was higher through thin 3Y-TZP at any time compared to thick 3Y-TZP. For the line scanning method, short distances (2 and 4 mm) resulted in a significant increase in temperature for 0.5-mm thick specimens. Laser irradiation significantly decreased the SBS of the 0.5-mm group compared to the nonirradiated group. After irradiation, the bond strength of the 2- and 3-mm thick 3Y-TZP was similar to the nonirradiated group. Conclusions: The temperature and bond strength of low-power laser irradiated 3Y-TZP specimens was affected by the specimen thickness but not by the irradiation time tested. Low-power laser irradiation is an effective debonding method for thin Y-TZP restorations.

Purpose: To evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intracoronal preparation designs. Materials and Methods: An examination of the marginal adaptation of two materials—lithium disilicate (LD; IPS e.max CAD) and polymer infiltrated ceramic network material (PICN; Vita Enamic)—and two preparation designs, where D1 represents MOD inlay preparation with no cusp reduction and for D2, in addition to the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. Four sub-groups (LD-D1, LD-D2, PICN-D1, PICN-D2) were conducted. In total, 40 (n = 40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, SD, minimum, maximum, and 95% CI. Pairwise comparisons using Tukey post-hoc test were performed following an ANOVA significance of P ≤ .05. Results: The results revealed that lithium disilicate showed statistically significantly higher mean gap distance than PICN material (61 μm to 99 μm). Pairwise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Conclusions: Both LD and PICN material provided marginal adaptation within clinical accepted range. PICN material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional preparation. Keywords: Glass Ceramic; Hybrid Ceramic; Marginal gap; Partial coverage.

Purpose: To evaluate the influence of abutment material, cement thickness, and crown type on the esthetics of implant supported restorations. Material and Methods: In total, 60 specimens were prepared to represent six abutment groups: Group PA = pink-anodized Ti; Group GA = gold-anodized Ti; Group T = nonanodized Ti; Group H = hybrid (Ti + zirconia); Group P = PEEK (Ti + PEEK); and Group C = composite resin (control). Crown specimens (n = 120) were obtained from Vita Enamic (VE) and Vita Suprinity (VS). Two cement thicknesses (0.1 and 0.2 mm) were used. The color values of crown configura:ons were measured and ΔE₀₀* values were calculated. Statistical analyses included were Shapiro Wilk, three-way ANOVA, and Tukey HSD tests (P ≤ .05). Results: Abutment (P < .001) and crown materials (P = .001) had a significant effect on ΔE₀₀* values, while cement thickness did not. Groups PA and H resulted in significantly lower mean ΔE₀₀* values than other abutments, whereas Group T revealed the highest. Unlike VS, cement thicknesses created a significant difference on the ΔE₀₀* values for VE (P ≤.05). Conclusions: Pink-anodized Ti or hybrid abutments for VE and pink- or goldanodized Ti for VS seem to be better options, in terms of color change. Cement thickness of 0.1 mm resulted in higher ΔE₀₀* value than 0.2 mm for VE (P ≤ .05).

Purpose: To evaluate the behavior of hybrid abutment crowns fabricated from monolithic lithium disilicate ceramic (LDC) and to compare the influence of different in vitro artificial aging protocols. Materials and Methods: A total of 32 monolithic hybrid abutment crowns of monolithic LDC were fabricated. Of these, 24 were artificially aged using three different protocols up to a 20 year simulation (1.2 × 10⁶, 2.4 × 10⁶, 4.8 × 10⁶ chewing cycles, thermocycling), a control group underwent no artificial aging (n = 8, N = 32). Load-to-failure tests were conducted for all specimens, and failure values were compared (P < .05). Results: All specimens passed in vitro aging. Mean failure load values between 532.6 and 562.8 N were found but did neither differ significantly among the test groups nor from the control group. Conclusions: Within the limitations of this in vitro pilot study, hybrid abutment crowns manufactured from monolithic LDC seem to offer appropriate long-lasting mechanical stability over a simulation period up to 20 years. The failure values and complication pattern seem to be independent of several aging protocols in this test set-up.