The International Journal of Prosthodontics, 06/2024

Purpose: To analyze the association of temporomandibular disorders (TMDs) and somatic symptoms with the psychologic variables of personality, coping, and distress in young adults. Physical and psychologic correlates were also explored, along with the risk factors for TMDs/somatization. Materials and Methods: Participants were enlisted from a local university, and the presence of TMDs and somatic symptoms was determined with the Short-form Fonseca Anamnestic Index and Patient Health Questionnaire-15. The psychologic variables of personality, coping, and distress were assessed with the Big-Five Personality Inventory-10; brief-COPE Inventory; and Depression, Anxiety, Stress Scales-21, respectively. Statistical evaluations were performed with Mann-Whitney U test, Spearman correlation, and logistic regression analyses (α = .05). Results: Among the 455 participants (mean age: 22.7 ± 1.2 years), 18.2% and 5.7% had TMDs and medium-to-high somatization, respectively. Participants with TMDs exhibited substantially higher somatization and psychologic distress scores than those with no TMDs. Significant differences in TMDs, conscientiousness, extraversion, and psychologic distress scores were observed between participants with no-to-mild and medium-to-high somatization. The association between TMD and somatization scores was weak but significant. Neuroticism and dysfunctional coping style were moderately correlated to general distress, depression, anxiety, and stress (rs = 0.44 to 0.62). Conclusions: Findings suggest that anxiety is the main risk factor for the presence of TMDs and medium-tohigh somatization in nonclinical young adults, while conscientiousness is a protective factor for somatization.

Purpose: To evaluate the facial esthetics of complete denture treatment using a 3D analysis of the lower third of the face before and after treatment by comparing and correlating measurements. Materials and Methods: A total of 31 edentulous patients were enrolled, and 3D images were captured before (T1) and after (T2) complete denture delivery. Twelve landmarks were established in the face. Linear, angular, surface, and perimeter measurements were evaluated and compared with paired t test. The delta (Δ) values (T2–T1) were assessed using Spearman correlation to verify the associations between all measurements according to the facial parameters (α = .05). Results: Statistical differences were identified in the lower third of the face in the linear measurement Sn-Gn (P = .006), the angular measure Tright-Pg-Tleft (P = .004), and at the surface of the lower third of the face (P = .001). All measurements were statistically different in the labial protrusion area: the nasolabial angle (Prn-Sn-Ls), the surface, and the perimeter (P = .001). In the lip evaluation, statistical differences were observed in the linear (Ls-Li), surface, and perimeter measurements (P = .001). Conclusions: The facial esthetic proportions of the linear and perimeter measurements increased and the angles of sealed lips and nasolabial and lower facial convexity decreased after complete denture delivery. The present study showed a clinically important correlation between linear and angular measurements that should help restore facial esthetics, providing metrics that can aid the clinician in facial composition.

Purpose: To evaluate the circumferential bone level and morphologic changes in the posterior mandibular ridge of mandibular overdenture wearers submitted to conventional and immediate loading through CBCT at 1 and 3 years. Materials and Methods: In total, 20 participants who received two narrow-diameter implants (NDIs; Facility-Equator, Neodent; 2.9 × 10 mm) were randomly allocated to the conventional loading (CL; n = 10) or immediate loading (IL; n = 10) group. CBCT scans were performed in each group to analyze the vertical bone level (VBL) and horizontal bone level (HBL) around the implants, analyzed together with the posterior bone remodeling of the mandible measured at distances of 5, 10, 15, and 20 mm from the mental foramen (L1 to L4, respectively). Differences between groups were verified using Student t test at a significance level of 5%. Results: The IL group showed a significantly higher HBL in the first year (P = .028) and a significantly higher VBL in the third year (P = .032), with an HBL of –0.22 mm and VBL of –0.59 mm, respectively. After the third year, the percentage of cortical and medullary height indicated that the IL group presented a significantly higher percentage of cortical bone height (40.1 ± 9.3 mm) compared to the CL group (31.8 ± 5.8 mm) at position L1 (P = .05). No difference was found for posterior ridge remodeling (P > .05). Conclusions: The IL group showed slightly higher HBL and VBL values and locally displayed more replacement of medullary bone by cortical bone. However, circumferential bone levels in the IL group were still clinically acceptable, and the posterior resorption rate remained stable after 3 years of function, irrespective of the loading type.

Purpose: To investigate the medium-term survival of Dalbo-Rotex retention elements, identify potential risk factors for complication or loss, and consider economic factors. Materials and Methods: Patients treated with Dalbo-Rotex retention elements in a university setting were retrospectively identified and examined. Clinical data comprised assessments of the dental, periodontal, endodontic, and prosthetic situation, including radiographic analysis. Patient satisfaction was quantified with visual analog scale questionnaires. Five-year Kaplan-Meier plots for relative survival and success rates were calculated. Results: The 45 included patients had a total of 76 Dalbo-Rotex retention elements. Of these, 12 Dalbo-Rotex elements failed and complications occurred in 42.1% of elements, equating to a survival rate of 84.2% and a success rate of 47.4% after a mean observation period of 49.2 ± 52.4 months (range: 6 to 219 months). The 5-year cumulative survival and success rates were 62.4% (95% CI: 44.0% to 88.4%) and 35.6% (95% CI: 23.8% to 53.2%), respectively. Patients’ self-assessment of prosthesis retention was rated at 82 (IQR 40 to 92.2) with low pain perception at 4.5 (IQR 0 to 30). Probing pocket depth levels were significantly reduced in patients adhering to a regular recall interval compared with those with longer intervals. Conclusions: Chairside Dalbo-Rotex retention elements are a straightforward chairside method for prosthesis retention that achieve good survival over medium-term follow-ups with high patient satisfaction. This technique is therefore a viable alternative to cast post copings and can be particularly valuable for patients with limited financial resources.

Purpose: To evaluate the effects of an ergonomic dentist stool design on muscle activity and fatigue in dentists. Materials and Methods: A total of 14 dentists were recruited, and electrodes were attached to the arm, neck, and shoulder muscles of these dentists according to the surface electromyography (EMG) for the noninvasive assessment of muscles protocol. After measuring the maximal voluntary contraction, eightchannel surface EMG was performed during simulations of two dental procedures (intraoral scanning and tooth preparation) while the dentists were using two types of dentist stools. Furthermore, muscle activity and fatigue were determined based on eight-channel surface EMG data, and ergonomic risk levels were evaluated according to the muscle activity. Shapiro-Wilk test was used to confirm that all data were normally distributed, and Mann-Whitney U test was used to compare the two types of dentist stools (α = .05). Results: There was a significant difference between the conventional and ergonomically designed dentist stools in terms of the activity of the trapezius descendens muscle (P < .05). Notably, the activity of the trapezius descendens muscle was less when the dentists used ergonomically designed dentist stools than when they used a conventional dentist stool. The activity of all muscles, except for the sternocleidomastoid, indicated moderate ergonomic risk. Conclusions: A dentist stool that enables dentists to maintain ergonomic posture should be used to prevent musculoskeletal disorders.

Purpose: To investigate the effect of BruxZir Steel treatment on the fracture resistance of zirconia threeunit bridges prepared using 5Y-PSZ–based zirconia blanks. Materials and Methods: Three-unit zirconia bridges were milled using CAD/CAM from homogeneous bisque zirconia blanks (5Y-PSZ–based) supplied by various manufacturers and sintered. Fracture resistance was analyzed with dynamic loading. For each zirconia blank, the fracture resistance of the sintered test restoration (cementation surface treated with BruxZir Steel) was compared to the sintered control restoration (untreated cementation surface). Finite element analysis (FEA) was used to analyze the stress distribution on the three-unit bridge under an axial load. Results: The fracture resistance of the test restorations was significantly higher than that of the control restorations for all manufacturers considered in this study (P < .05). Furthermore, the restoration made of BruxZir Esthetic treated with BruxZir Steel had the highest fracture resistance compared to the other restorations. In addition, the three-unit bridge restorations prepared from 5Y-PSZ–based zirconia blanks exhibited differences in grain size and fracture toughness depending on the presence or absence of BruxZir Steel treatment. The locations of high stresses under FEA correlated well with the fracture locations in the corresponding experimental test. FEA also demonstrated the improved performance of the BruxZir Steel–treated sample compared to the control. Conclusions: The fracture resistance of 5Y-PSZ–based BruxZir Steel–treated three-unit bridges was significantly higher (min = 30%, max = 198%) than the control.

Purpose: To evaluate the effect of toothbrushing on the surface roughness (Sa), roughness profile (Rv), gloss units (GU), and surface morphology of three glazed ceramics. Materials and Methods: Specimens (n = 7) were made from the following different CAD/CAM materials and evaluated: lithium disilicate–based glass ceramic (EM); zirconia-reinforced lithium silicate glass ceramic (CE); and 6 mol% yttria partially-stabilized zirconia (IN). IPS e.max CAD (EM) and InCoris (IN) specimens were sintered, and all groups were prepolished and glazed according to the manufacturer’s recommendations using IPS Ivocolor Glaze Paste (Ivoclar Vivadent) or Universal Overglaze High Flu (Dentsply/Sirona). Sa, Rv, GU, and morphology were analyzed before and after brushing at 30,000, 120,000, and 180,000 cycles. The data of Sa and GU were analyzed with ANOVA two-way and post hoc Tukey tests (α = .05). Rv was analyzed with Kruskal-Wallis and Student-Newman- Keuls tests. Surface morphology was analyzed qualitatively. Results: Sa decreased significantly after 180,000 toothbrushing cycles for all materials tested. CE showed higher Rv than EM and IN, and IN showed the highest GU after 180,000 toothbrushing cycles, which promoted a polishing effect for all materials. Conclusions: Long-term toothbrushing did not jeopardize the glazed surface of all tested materials compared to lack of brushing.

Purpose: To evaluate and compare bacterial growth on zirconia vs titanium healing caps. Materials and Methods: Streptococcus sanguinis (Ss) and Ftreptococcus nucleatum (Fn) were grown on titanium and zirconia healing caps that were fixed to the cover of a 96-well microtiter plate. A drop (10 μL) of bacterial suspension was placed on each healing cap and allowed to dry for 1 hour at 37°C. After this time, the cover was replaced on the plate such that the caps were completely immersed in fresh liquid medium. Each plate contained only one bacterial strain, with two control groups. Bacterial growth was monitored over 18 hours by following the optical density (OD) at 650 nm. One-way ANOVA comparison test was used for statistical analysis. Scanning electron microscope (SEM) images of healing caps of each material were taken after 48 hours of incubation with Ss or Fn to assess bacterial attachment and with no bacteria as a negative control. Results: Ss growth was similar in both types of healing cap, with no significant differences between these groups and the control (P = .990). However, there was significantly less growth of Fn on the zirconia caps than on the titanium samples (P < .0001) or the control (P < .0001). SEM imaging revealed obvious differences in the surface characteristics of the titanium and zirconia caps. The number of bacteria attached to the rough apical area was particularly high. Conclusions: The use of zirconia healing caps may reduce the growth of some bacterial species compared to that seen on titanium healing caps.

Purpose: To investigate the effects of recycling lithium disilicate (LD), surface treatment, and thermocycling on the bond strength to resin cement. Materials and Methods: A total of 72 tablets (10 × 10 × 3 mm) of LD were made according to the recycling cycle with 24 tablets for each strategy: control (conventional sintering), 1R (1 recycling cycle), and 3R (3 recycling cycles). For the recycling groups, tablets were waxed, mounted in a silicone ring, and poured with investment material, and residues of sintered LD tablets were pressed by the lost wax technique. The residual LD was reused as described until it reached 3R. Afterward, the tablets were embedded in acrylic resin, sanded, and divided (n = 15) according to the factors of “surface treatment” (hydrofluoric acid [HF] for 20 seconds [HF20s] and silane, HF for 120 seconds [HF120s] and silane, and Monobond Etch & Prime [MEP]) and thermocycling (TC; with 10,000 cycles and without). After surface treatment, cylinders (diameter: 2 mm) of resin cement were made and submitted to SBS test (100 kgf, 1 mm/minute). Data (MPa) were analyzed by three-way ANOVA, Tukey test (5%), and Weibull analysis. Failure analysis was performed with a stereomicroscope. Results: ANOVA revealed that all factors were significant (P = .000*). The group 3RMEP (105.09 ± 19.49) presented the highest SBS among the experimental groups. The 1RHF20s^Tc (7.50 ± 1.97) group had the lowest SBS, similar to CHF20s^Tc (15.69 ± 3.77), 1RHF20s (15.12 ± 3.03), 1RHF120s^Tc (14.60 ± 3.43), and 3RHF20s^Tc (15.65 ± 0.97). The Weibull modulus and characteristic strength varied among the experimental groups (P = .0). Failure analysis revealed adhesive and mixed types. Conclusions: The recycling of DL ceramics increases the SBS to resin cement when the ceramic is treated with HF120s and silane or MEP. Schlagwörter: Shear Strength, lithium disilicate, recycling.

Purpose: To evaluate the clinical and patient-reported outcomes of a minimally invasive suturing technique for esthetic crown lengthening surgery (ECLS). Materials and Methods: A total of 15 patients who underwent ECLS were treated using the described suturing technique. Clinical parameters, including plaque index (PI), gingival index (GI), bleeding index (BI), papilla index score (PIS), early wound healing index (EHI), visual analog scale (VAS), pink esthetic score (PES), and white esthetic score (WES), were recorded at baseline, immediately postsurgery, and during follow-up visits spanning 5 days to 24 months. Two-sample t test was performed to evaluate statistical significance (α = .05). Results: All patients (100%) reported a high level of satisfaction, with stable high postoperative VAS scores. From baseline to 5 days postoperative, there was no statistically significant increase in PI, although there was a slight deterioration observed in GI (0.13 ± 0.23, P < .05) and BI (0.49 ± 0.55, P < .05). Early wound healing (EHI 1) was achieved by all patients at 5 days postsurgery. Additionally, 3 patients exhibited changes in PIS within the initial 3 months following surgery, after which all patients attained an optimal degree of papilla fill (degree III). Conclusions: The application of the minimally invasive esthetic suturing technique in ECLS demonstrates favorable outcomes in terms of patient satisfaction and long-term stability. However, the assertion of its superiority over conventional suturing methods for ECLS necessitates substantiation through rigorous investigation via well-designed randomized controlled clinical trials.

Purpose: To investigate the influence of milling parameters on the durability and fracture force of resinbased composite crowns during in vitro aging simulation. Materials and Methods: Identical molar crowns (n = 8 per group) were milled from resin-based composite crowns (Grandio, VOCO Dental) with different processing speeds (soft, normal, fast) or levels of detail (very high, high, low) from 98-mm disks. One group was milled wet to investigate the influence of cooling. The influence of polishing was tested in two groups. All crowns were adhesively bonded on standardized resin-based composite molars. Aging was performed with thermal cycling and mechanical loading (2 × 3,000 × 5°C/55°C, 2 minutes, H₂0 dist., 1.2 × 10⁶ force at 50 N). Fracture forces were determined (v = 1 mm/minute, Z010, Zwick Roell). Results: For statistical analysis, Pearson correlation, one-way ANOVA, and Bonferroni post hoc tests were used (α = .05). All crowns survived thermal cycling and mechanical loading (TCML) without any failures. The fracture values varied between 1,237.3 ± 326.7 N and 3,308.6 ± 655.8 N. Significant (P < .001) differences between the individual manufacturing approaches were detected. Failure was categorized as a fracture of the crown and partial loosening of the crown. No different failure pattern was observed between the tested systems. Conclusions: A medium level of detail seems to be ideal to achieve the highest fracture forces. No relationship existed between machine speed and fracture force. Fracture force was not affected by wet grinding. In individual cases, polishing reduced crown fracture values due to reduced wall thickness.

Purpose: To review the oral prosthetic rehabilitation of patients with epidermolysis bullosa hereditaria (EBH) and study the level of evidence and quality of the presented available articles and establish clinical recommendations for the prosthetic management of these patients. Materials and Methods: An electronic search was done in July 2022 in five databases following PICOTS elements. The quality of the reports was established using the modified Pierson, Bradford Hills, and Ottawa Newcastle scale. Results: Data extracted from 19 case reports for protocolized analysis corresponded to 64 patients and 80 dental prostheses, with almost 9 out of 10 patients being completely edentulous. The distribution of EBH types was 84% dystrophic, 10.5% junctional, and 5.5% simplex. The difficulties encountered by the authors synthesized in this review characteristically reflected those most likely encountered in dental practice. Most rehabilitations were implant-supported prostheses (85%), followed by removable dentures (10%) and dental-supported rehabilitations (5%). Fixed full-arch implant-supported prostheses represented 76.4% of implant-supported prostheses, and this prosthetic solution reflected the highest scientific quality. Conclusions: For an individualized approach to treatment, we recommend that in cases of total edentulism, fixed full-arch implant-supported prostheses are the most appropriate because they allow the best computer-aided planning, design, manufacture, and fitting of the prosthesis in such a complex clinical context.

Purpose: To describe a digital workflow for the management of the emergence profile and the restoration’s finishing line on vertically prepared teeth using a digital data set. Materials and Methods: Three scans (the prepared teeth the day of the preparation, the provisional restoration placed on the preparation after soft tissue maturation, and the provisional restoration outside of the oral cavity) were combined under a common data set to provide the necessary information to design the final restoration. Results: The digital technique presented can facilitate the implementation of the vertical preparation, because the desired finish line can be defined by the clinician and be transferred predictably to the dental lab. The current approach provides an alternative gingival management method, taking advantage of the displacement of soft tissue after vertical preparation. Conclusions: Positioning of the final finishing line on vertically prepared teeth, management of soft tissue, and fabrication of the final restoration can be facilitated with this approach, combining a digital data set that has been obtained during a distinct phase of the treatment.

Purpose: To assess wear, fatigue, and fracture resistance of different CAD/CAM onlays milled from monolithic zirconia (ZR), hybrid ceramic (EN), and lithium disilicate (LS) when used as abutments for removable partial denture frameworks fabricated from acetal resin (AR) or cobalt-chromium (Co-Cr). Materials and Methods: Standard onlays and RPD framework were designed and milled using CAD/CAM. Onlays were cemented with resin cement to identical teeth models. The RPD’s occlusal rest surface and the ceramic onlays’ rest seats were both 3D scanned before and aPer 750,000 mechanical load cycles (50 N) and 8,000 thermal cycles (5° to 55°C) in a chewing simulator. The volumetric loss was measured using 3D-image processing software, and the failure of the samples was detected using a stereomicroscope. The fracture resistance was tested by loading to failure in a universal testing machine. The fatigue failure results were analyzed with Fisher exact probability test, and the wear and fracture resistance data were analyzed using twoway ANOVA and Bonferroni post-hoc test (P < .05). Results: A significant difference (P < .05) was found between the tested experimental groups in wear, fatigue, and fracture resistance. Zr/Co-Cr combinations exhibited the least wear and the highest fatigue and fracture resistance (P < .05), while the highest wear and least fatigue and fracture resistance were recorded for the EN/AR group (P < .05). Conclusions: Zr onlays demonstrated a conserva+ve treatment option with superior mechanical behavior when used as an onlay abutment, regardless of the RPD framework material used. The AR framework is not recommended in the posterior region for removable partial dentures.

Purpose: To evaluate the tensile strength of five different thicknesses of two resin cements placed between two titanium surfaces, before and after aging. Materials and Methods: One hundred grade-5 titanium models were used, each composed of two surfaces simulating a semiprecision attachment for overdenture and its housing in the framework. Samples were cemented using two different resin cements (SoloCem and OT-Cem). Five groups representing five different cement thicknesses (from 50 to 250 μm) were created by varying the housing diameter. Half of the samples underwent a tensile strength test 24 hours after luting, while the other half underwent a tensile strength after 30,000 thermic cycles from 5°C to 55°C. Shapiro-Wilk and ANOVA with post-hoc tests were performed to relate the tensile strength to the variables: cement type, thermal aging, and cement thickness (P < .05). Results: Statistical differences were found between the cements both at T0 and T1; the mean values of tensile strength of SoloCem were three times higher than those of OT-Cem. The thermic cycles determined a reduction of the tensile force values for both cements; statistical evidence was found only for the SoloCem, except for the 100 μm thickness group. Significant differences were also found between the cement thicknesses of both cements, with 50 μm and 100 μm expressing the best tensile strength. Most of the fractures were of cohesive nature. Conclusions: SoloCem showed a higher tensile strength than OT-Cem but was more stressed by aging. For each group, the cement thickness influenced the tensile strength values with an inverse relationship. 

Purpose: To investigate the microscopic structure and fracture toughness of two pressable glass-ceramics—GC Initial LiSi Press (LiSi) and IPS e.max Press (e.max)—with different levels of translucency. Materials and Methods: Two groups each of LiSi and e.max, with medium opacity and high translucency levels, were examined. The crystal morphology of acid-etched specimens was observed under a scanning electron microscope (SEM). Six specimens in each group were fabricated in a square shape (12 ´ 12 ´ 1.5 mm) to measure translucency parameters (TP) using a spectrophotometer. Ten bar-shaped specimens in each group with dimensions of 23 x 2 x 4 mm were used to determine the fracture toughness (KIc) by a surface crack in flexure (SCF) using a universal testing machine. One-way ANOVA and Scheffe post-hoc tests were used for statistical analysis. Results: LiSi showed fine dense crystals 1 to 1.5 μm in size, while e.max showed long rod-shaped crystals 3 to 4 μm in size. The TP values of all specimens coincided with their translucency levels. There was no statistical difference in the K_Ic between different translucency for both ceramics (P < .05). However, the K_Ic of e.max was significantly higher than that of LiSi at both translucency levels. As a result of larger and longer crystals, e.max provided better crack deviation mechanism to resist the fracture. Conclusions: Within the limitations of this study, the translucency levels of both lithium disilicate ceramics did not affect the fracture toughness of the materials. The fracture toughness of e.max was statistically higher than LiSi.