Effect of a calibration aid and the intraoral scanner on the registration of a partially edentulous maxilla: An in vitro study.

STATEMENT OF PROBLEM: Precise data are a prerequisite for accurately fitting restorations. Therefore, intraoral scanners have to be reliable. Data on differences between the same model of intraoral scanning systems are lacking. PURPOSE: This in vitro study evaluated differences in the scanning accuracy of a partially edentulous maxilla between combinations of new intraoral scanners of a single model from the same manufacturer (Primescan; Dentsply Sirona) and several calibration aids. MATERIAL AND METHODS: The in vitro reference model simulated a maxilla with 6 prepared teeth for a complete arch fixed partial denture. Five precision ceramic balls were used to detect dimensional deviation between the reference model and the scan. Distances were divided into 4 categories, from short distances between 2 neighboring precision balls to the cross-arch distance with the scan path comprising all 5 balls. For each combination of 4 new intraoral scanners and their respective calibration aids, 12 model registrations were generated. The data were statistically analyzed using ANOVA (α=.05). RESULTS: Distance deviations increased with increasing scan path length and were significantly affected by the covariates "scanner" (P≤.023) and, for 3 of 4 distance categories, the "calibration aid" (short, medium, and long distances: P≤.013). For short and medium distances, acceptable scanning results were achieved for all test groups. The largest deviation was 539 µm for the cross-arch distance. CONCLUSIONS: Scanning accuracy depends on the scanner and the calibration aid used, in particular, for spans exceeding a single quadrant.

Biaxial flexural strength of 3D-printed 3Y-TZP zirconia using a novel ceramic printer.

OBJECTIVES: To compare the strength and reliability of 3D-printed 3Y-TZP zirconia manufactured with various printing orientations and staining. MATERIALS AND METHODS: A total of one-hundred cylindrical zirconia specimens were designed and fabricated using 3D printing and processed according to ISO 6872 standards. Of these specimens, 80 were 3D printed using the new ZIPRO-D (ZD) 3D ceramic printer. In this ZD group, 60 specimens were printed in a vertical orientation and were either stained after debinding (ZD1, x-orientation, n = 20) or not stained (ZD2, x-orientation, n = 20; ZD3, y-orientation, n = 20) and the remaining 20 specimens out of n = 80 were printed in a horizontal orientation (ZD4). Further 20 specimens out of the entire sample N = 100 were printed vertically with the CeraFab7500 3D ceramic printer (LC). All completed specimens were loaded until fracture using a universal testing machine. Biaxial flexural strengths and Weibull parameters were computed for the ZD groups and for the LC group. Group and sub-group effects were evaluated using Welch ANOVA (alpha = 0.05). RESULTS: The mean (standard deviation, SD) biaxial flexural strengths of vertically oriented ZD samples with (ZD1) and without (ZD2/ZD3) staining were 811 (197) and 850 (152) MPa, respectively (p > 0.05). The ZD4 (horizontally printed), 1107 (144) MPa, and LC (1238 (327)) MPa samples had higher mean (SD) flexural strengths than the ZD1-3 specimens. No difference was observed between the ZD4 and LC group (p > 0.05). Weibull moduli were between m = 4.6 (ZD1) and 9.1 (ZD4) in the ZD group and m = 3.5 in the LC group. CONCLUSIONS: All tested 3D-printed zirconia specimens exceeded the flexural strengths required for class 5 restorations according to ISO 6872 standards. While the flexural strengths of zirconia printed using the novel ZD device in the vertical orientation are lower than those of zirconia printed using the LC printer, the ZD printer shows at least comparable reliability. CLINICAL RELEVANCE: 3D-printing of zirconia is a new technology in dental application. Based on the presented strengths values, clinical application of 3D-printed zirconia for fixed dental protheses can be recommended.

A German version of the Oral Impacts of Daily Performances-reliability and validity.

OBJECTIVE: The Oral Impact of Daily Performances (OIDP) is a dental patient-reported outcome measure (dPROM) for the estimation of oral health-related quality of life (OHRQoL) and takes the frequency as well as the severity of problems into account; however, it is not available in German language. The aim of this study was, therefore, to evaluate the reliability and validity of the German version of the OIDP in patients of a private practice. MATERIAL AND METHODS: Translation of the original OIDP version was performed by a forward-backward process. Reliability was evaluated in terms of construct stability (test-retest) for the single items and the sum scores. The responsiveness to change in oral health status was assessed by pre- and post-treatment comparison, in addition. Validity was assessed as convergent validity in comparison with other dPROMs (OHIP-14; GOHAI) and objective dental findings. RESULTS: A total of 330 patients participated in this study (mean age: 42.0 (18.0)). The OHRQoL of the participants was relatively high (OIDP score 4.3 (SD 14.3), OHIP score 4.8 (SD 5.3), GOHAI score 54.2 (SD 5.4)). A moderate construct stability for the total OIDP-score (ICC 0.686) was found whilst reliability for the single items varied between 0.179 (social contact) to 0.559 (showing teeth). Significant correlations were found for OIDP and OHIP (p < 0.001; r = 0.361) and OIDP and GOHAI (p < 0.001; r = - 0.391) indicating moderate validity with a tendency to even stronger correlations for OIDP-s and OIDP-f (r ≥ 0.500). CONCLUSIONS: The German version of the OIDP demonstrated sufficient reliability and validity. OIDP's general performance should be interpreted cautiously as the outcome was detected in a specifically healthy population. CLINICAL RELEVANCE: The OIDP is yet the only dPROM that evaluates both severity as well as frequency which makes validation interesting regarding specific target populations.

Initial damage and failure load of zirconia-ceramic and metal-ceramic posterior cantilever fixed partial dentures.

OBJECTIVES: The aim of this study was to compare failure load and initial damage in monolithic, partially veneered, and completely veneered (translucent) zirconia cantilevered fixed partial dentures (CFPDs), as well as completely veneered metal-ceramic CFPDs under different support and loading configurations. MATERIALS AND METHODS: Eight test groups with anatomically congruent CFPDs (n = 8/group) were fabricated, differing in CFPD material/support structure/loading direction (load applied via steel ball (Ø 6 mm) 3 mm from the distal end of the pontic for axial loading with a 2-point contact on the inner cusp ridges of the buccal and oral cusps and 1.3 mm below the oral cusp tip for 30° oblique loading): (1) monolithic zirconia/CoCr abutment teeth/axial, (2) monolithic zirconia/CoCr abutment teeth/oblique, (3) partially veneered zirconia/CoCr abutment teeth/axial, (4) partially veneered zirconia/CoCr abutment teeth/oblique, (5) completely veneered zirconia/CoCr abutment teeth/axial, (6) completely veneered CoCr/CoCr abutment teeth/axial (control group), (7) partially veneered zirconia/implants/axial, and (8) partially veneered zirconia/natural teeth/axial. Restorations were artificially aged before failure testing. Statistical analysis was conducted using one-way ANOVA and Tukey post hoc tests. RESULTS: Mean failure loads ranged from 392 N (group 8) to 1181 N (group 1). Axially loaded monolithic zirconia CFPDs (group 1) and controls (group 6) showed significantly higher failure loads. Oblique loading significantly reduced failure loads for monolithic zirconia CFPDs (group 2). Initial damage was observed in all groups except monolithic zirconia groups, and fractography revealed design flaws (sharp edges at the occlusal boundary of the veneering window) in partially veneered zirconia CFPDs. CONCLUSIONS: Monolithic zirconia CFPDs might be a viable alternative to completely veneered CoCr CFPDs in terms of fracture load. However, oblique loading of monolithic zirconia CFPDs should be avoided in clinical scenarios. Design improvements are required for partially veneered zirconia CFPDs to enhance their load-bearing capacity. CLINICAL RELEVANCE: Monolithic zirconia may represent a viable all-ceramic alternative to the established metal-ceramic option for CFPD fabrication. However, in daily clinical practice, careful occlusal adjustment and regular monitoring should ensure that oblique loading of the cantilever is avoided.

Fracture Resistance of Posterior Tooth-Supported Cantilever Fixed Dental Prostheses of Different Zirconia Generations and Framework Thicknesses: An In Vitro Study.

The rehabilitation of free-end situations is a frequent indication in prosthetic dentistry. Cantilever fixed dental prostheses (cFDPs) made of 1st and 2nd generation zirconia are one treatment option. Due to a unique gradient technology, combinations of different zirconium dioxide generations are thus feasible in one restoration. However, data about these materials are rare. The purpose of this study was therefore to investigate the fracture resistance and fracture modes of tooth-supported cFDPs fabricated from different zirconia materials (gradient technology) and different framework thicknesses. A total of 40 cFDPs were fabricated using the CAD/CAM approach and belonged to five test groups. The different groups differed in the yttria content, the proportion of the tetragonal/cubic phases, or in wall thickness (0.7 mm or 1 mm). After completion, the cFDPs were subjected to thermal cycling and chewing simulation (1.2 × 106 load cycles, 108 N load). Afterwards, cFDPs were statically loaded until fracture in a universal testing machine. A non-parametric ANOVA was compiled to determine the possible effects of group membership on fracture resistance. In addition, post-hoc Tukey tests were used for bivariate comparisons. The mean fracture loads under axial load application ranged from 288 to 577 N. ANOVA detected a significant impact of the used material on the fracture resistances (p < 0.001). Therefore, the use of cFDPs fabricated by gradient technology zirconia may not be unreservedly recommended for clinical use, whereas cFPDs made from 3Y-TZP exhibit fracture resistance above possible masticatory loads in the posterior region.

In vitro pilot study comparing a novel implantoplasty sonic instrumentation protocol with a conventional protocol using burs.

BACKGROUND AND OBJECTIVES: The aim of implantoplasty (IP) is to remove titanium implant layers that have been contaminated and to smoothen the implant surfaces so they retain less plaque. However, existing IP methods are very invasive and reduce implant wall thickness. AIM: To investigate the suitability of novel sonic tips in IP and to compare this novel protocol with conventional abrasive procedures. MATERIALS AND METHODS: Thirty dental implants (Ø 4.1 mm, 10 mm length) were distributed in three groups and investigated according to the protocol of Sivolella et al., with modifications to the instrument's feed rate, the applied contact force, and the speed of implant rotations per minute. The upper third of the implant was processed with a diamond-coated bur (BUR) or novel non-diamond-coated sonic tips (AIRSCALER). After standardized IP, the surfaces were analyzed by tactile profilometry and scanning electron microscopy (SEM). Changes in implant weight, implant material loss, and implant fracture strength were assessed. RESULTS: The mean roughness (Ra , Sa ), implant material loss, and change in implant weight were significantly lower in the AIRSCALER group than in the BUR group, whereas the mean compression resistance values were significantly higher in the AIRSCALER group than in the BUR group. CONCLUSIONS: IP with uncoated sonic tips smoothes the surfaces and reduces structural loss of the implant in the area of microthreads. This new IP method could be of great clinical importance, especially for implants with microthreads and reduced diameter or wall thickness.

Effect of firing time and wall thickness on the biaxial flexural strength of 3D-printed zirconia.

OBJECTIVES: To evaluate the effect of accelerated firing on 3D-printed zirconia. METHODS: To check if formulae provided by ISO 6872 can be extended to thin samples, finite element analyses were carried out in advance of fabricating 3-mol% yttria-stabilized tetragonal zirconia polycrystal discs by milling and by 3D-printing. Four groups (n = 38 each) of 3D-printed specimens were produced with two nominal thicknesses (0.6 mm and 1.2 mm) and two firing strategies (long: 51 h, accelerated: 14.5 h). In the milled group (thickness 1.2 mm, n = 30), a standard firing program (9.8 h) was selected. Biaxial flexural strength tests were applied and mean strength, characteristic strength, and Weibull modulus were calculated for each group. Differences were analyzed using Welch ANOVA and Dunnett-T3 post-hoc tests. RESULTS: Maximum tensile stresses occurring during biaxial strength testing can be calculated according to ISO 6872 for thin samples with b > 0.3 mm. Variability of measured strengths values was smaller for milled zirconia compared with 3D-printed zirconia. The 1.2-mm-thick 3D-printed samples had significantly decreased strength after accelerated firing than after long firing. However, for the 0.6-mm-thick samples, comparable mean biaxial strength values of about 1000 MPa were measured for both firing protocols. SIGNIFICANCE: At the moment, long fabrication time for zirconia restorations is a major drawback of 3D-printing when compared with milling technology. This investigation showed that the strength of 0.6-mm-thick zirconia discs fabricated by 3D-printing was not impaired by accelerated firing. Thus, overnight firing of thin-walled 3D-printed zirconia restorations could be possible.

The Effect of Titanium Anodization on the Bond Strength of 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) Resin Cement.

PURPOSE: To examine the effects of anodization and different surface modifications of titanium on bond strength to 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) resin cement. MATERIALS AND METHODS: Grade 5 titanium alloy disks (n = 160) were assigned to one of five prebonding surface treatment study groups (polished; polished and anodized; polished, etched, and anodized; sandblasted; sandblasted and anodized). Disks were adhesively bonded with 10-MDP resin cement (Panavia 21; bonding area: 3.3 mm in diameter) to composite resin cylinders. In each study group, tensile bond strength tests were conducted after 24 ± 1 hours and after 6 months (180 ± 2 days) of water storage (n = 16 specimens per water storage subgroup). Debonded specimens were stereomicroscopically analyzed to determine their fracture mode. Statistics included one-way and multifactorial ANOVA and Tukey post hoc tests (α = .05). RESULTS: Anodization and water storage did not significantly (P ≥ .389) affect tensile bond strength. Although subgroups of polished samples had significantly (P ≤ .031) lower bond strengths (subgroup mean values: 20 to 26 MPa) than etched or sandblasted samples (subgroup mean values: 29 to 33 MPa), they nonetheless exceeded the empirical threshold of 10 MPa used as a criterion for clinical recommendation. The fracture mode of all test specimens was predominantly cohesive. CONCLUSIONS: Anodization of titanium surfaces can be performed without weakening the adhesion of 10-MDP-based resin cement to titanium.

Fit and Retention of Cobalt-Chromium Removable Partial Denture Frameworks Fabricated with Selective Laser Melting.

PURPOSE: To evaluate fit and retention of cobalt-chromium removable partial denture (RPD) frameworks fabricated with selective laser melting (SLM). METHODS: Three types of framework for clasp-retained RPDs were virtually designed and fabricated using SLM (n = 30). For comparison, 30 additional frameworks were produced using conventional lost-wax casting. A biomechanical model was created, incorporating extracted teeth mounted on flexible metal posts. Using this model, horizontal constraint forces resulting from a misfit were measured using strain gauges, while vertical forces were not recorded. The constraint force components and resultant forces were determined for all abutment teeth, and the maximum retention force during RPD removal from the model was also assessed. For statistical evaluation, the two fabrication methods were analyzed by calculating the means and standard deviations. RESULTS: The average horizontal constraint forces showed similar values for both fabrication methods (SLM: 3.5 ± 1.0 N, casting: 3.4 ± 1.6 N). The overall scatter of data for cast RPDs was greater compared to those fabricated using SLM, indicating a better reproducibility of the SLM process. With regard to retention, the intended retention force of 5-10 N per abutment tooth was not attained in one of the cast groups, while it was consistently achieved in all SLM groups. CONCLUSIONS: This in vitro study found that SLM is a promising option for the manufacture of cobalt-chromium RPD frameworks in terms of fit and retention.

Immediate loading of dental implants in edentulous mandibles using Locator attachments or Dolder bars: A 9-year prospective randomized clinical study.

AIM: To evaluate the long-term survival, incidence of prosthetic/technical and biological complications and the oral-health-related quality of life in patients with an edentulous mandible who were fitted with overdentures on two immediately loaded implants in the symphyseal area. MATERIALS AND METHODS: Forty-six patients with edentulous mandibles received two immediately loaded implant-retained dentures with either two Locator attachments or egg-shaped bar attachments. Implant outcomes were recorded after a period of observation of 9 years and included prosthetic complications, modified gingiva index (mGI), modified plaque index (mPI), oral health impact profile (OHIP-G) and radiographic estimation of bone loss. RESULTS: In 2020/2021, 27 patients with 54 implants were still available for follow-up. In total, nine implants in six patients were lost. Survival was 89.1% in the bar group and 91.3% in the Locator group. Implant success was 84.6% in the Locator group and 76.9% in the bar group. The mPI values were significantly higher in the bar group than in the Locator group, whereas no difference was seen in the mGI values. During the observation period, 152 prosthetic complications occurred, but the OHIP-G score did not differ significantly. CONCLUSIONS: There was no difference in implant survival between Locator or joint bar attachments over a 9-year observation period. Joint bar attachments were associated with slightly more complications, while patients in the Locator group were able to maintain better oral hygiene. The study was registered in the German Register of Clinical (Trials DRKS00004245).

The Impact of the SARS-CoV-2 Pandemic on Stress and Anxiety of Dental Students.

OBJECTIVES: To investigate the impact of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic on stress and anxiety of preclinical and clinical dental students. MATERIALS AND METHODS: Dental students (participants) in their clinical course (CC; n = 64) or preclinical course (PCC; n = 53) were included in the study. The subjective perceived levels of stress and anxiety were evaluated using the Dental Environment Stress (DES) questionnaire and the Depression, Anxiety and Stress Scales (DASS) questionnaire. Cortisol levels were measured in saliva samples collected from participants. Knowledge of the pandemic was evaluated using a 100-mm visual analog scale. All data were collected twice: once during the university holidays and once during term time. STATISTICAL ANALYSIS: Results from DES, DASS, and salivary cortisol tests were compared between baseline and follow-up using descriptive and bivariate statistics. Multivariate linear regression models were computed with DES, DASS, and cortisol values as dependent variables to analyze possible influencing factors. RESULTS: Participants showed medium levels of stress and anxiety at baseline and follow-up. The DASS score in the "anxiety" subdomain was significantly higher in the PCC group than in the CC group at baseline (p < 0.001) and increased during term time. DASS scores in the "stress" subdomain also increased during term time. However, both subdomain scores were lower than the cutoff value for a psychological disorder. The mean total DES scores were 615.9 ± 97.7 in the CC group and 580.40 ± 98.9 in the PCC group. These scores indicated medium stress levels and were not significantly different between the groups, nor did they change during the study period. Mean saliva cortisol levels were higher in the CC group (9.2 ± 5.2) than in the PCC group (4.9 ± 2.2) at baseline (p < 0.001) but converged by follow-up. Multivariate regression models showed that intraindividual perception of stress at baseline was consistently the most important aspect for changes in stress and anxiety levels during term time. The SARS-CoV-2 pandemic affected stress and anxiety levels in some participants, but this was not ubiquitous. CONCLUSION: Intraindividual differences in stress perception seem to be more relevant than course affiliation (preclinical or clinical) or the SARS-CoV-2 pandemic to stress and anxiety levels in dental students.

Metal-ceramic resin-bonded fixed partical dentures after a mean observation time of 7.5 years.

PURPOSE: The aim of the present study was to generate data on the long-term survival of metal-ceramic resin-bonded fixed partial dentures. MATERIAL AND METHODS: Eighty-nine participants, received 94 RBFPDs, 5 (n women = 1; n men = 4) received 2 RBFPDs each. All RBFPDs were fabricated as two-retainer end-abutment metal-ceramic restorations. Clinical follow-ups were performed 6 weeks after cementation and annually thereafter. The mean observation time was 7.5 years. Cox regression was performed to test the effects of the variables sex, location, jaw, design, use of rubber dam, and adhesive luting system Survival and success were calculated by using Kaplan-Meier curves. As a secondary objective, patient and dentist satisfaction with the esthetics and function of the RBFPDs was evaluated. The significance level was set at α = .05 for all calculations. RESULTS: Estimated Kaplan-Meier failure-free survival was 97.5% (standard error [SE] 1.7) after 5 years and 83.3% (SE 5.3) after 10 years. Calculated intervention-free survival (success) was 90.1% (SE 3.4) after 5 years and 65.5% (SE 6.7) after 10 years. Debonding-free survival was 92.6% (SE 2.9) after 5 years and 80.6% (SE 5.4) after 10 years. Cox regression revealed none of the four tested variables had a significant effect on the incidence of complications in RBFPDs. Patient and dentist satisfaction with RBFPD esthetics and function was consistently high throughout the observation period. CONCLUSIONS: Within the limitations of an observational study, RBFPDs achieved clinically successful outcomes over a mean observational period of 7.5 years.

Thermo-flexible resin for the 3D printing of occlusal splints: A randomized pilot trial.

OBJECTIVES: To compare the clinical performance of occlusal splints printed from thermo-flexible resin with milled splints. METHODS: A parallel two-arm pilot trial was initiated. Forty-seven patients (n women=38) were recruited from a tertiary care center and randomized using an online tool (sealed envelope). Inclusion criterion was an indication for treatment with a centric relation occlusal splint due to bruxism or any form of painful temporomandibular disorder. Patients were excluded if they were younger than 18 years, unable to attend follow-up appointments, or required another type of splint therapy. Patients received either, a 3D-printed (intervention group, V-print splint comfort, VOCO) or a milled splint (control group, ProArt CAD splint, Ivoclar). Construction software Ceramill M-splint (AmannGirrbach), 3D-printer MAX UV 385 (Asiga) and milling unit PrograMill PM7 (Ivoclar) were used. Follow-up assessments were conducted after 2 weeks and 3 months. Outcome measures were survival, adherence, technical complications, patient satisfaction on a 10-point Likert scale, and maximum wear using superimposition of optical scans. RESULTS: After 3 months, 20/23 intervention group and 18/24 control group participants were assessed. All splints survived. Minor complications were small crack formations on 6 printed and 4 milled splints. Mean patient satisfaction was 8 (SD 1.7) for printed, and 8.1 (SD 2.3) for milled splints (r = 0.1, p = .52). Median maximum wear was highly dispersed with 153 (IQR 140) in posterior and 195 (IQR 537) in frontal segments of printed, and 96 (IQR 78) respectively, 123 (IQR 155) of milled splints, (both: r = 0.31, p = .084). CONCLUSIONS: Within the limitations of a pilot trial, 3D-printed and milled splints performed similarly in terms of patient satisfaction, complication rates and wear behavior. CLINICAL SIGNIFICANCE: Thermo-flexible material was proposed for 3D printing of occlusal splints to overcome mechanical weaknesses of previously available resins. This randomized pilot study provides evidence that this material is a viable alternative to milled splints for at least three months of clinical use. Further evidence on long-term use should be obtained.

Oral Sequelae after Head and Neck Radiotherapy: RCT Comparing 3D-Printed Tissue Retraction Devices with Conventional Dental Splints.

OBJECTIVES: To evaluate oral sequelae after head and neck radiotherapy (RT) when using two different types of intraoral appliances. Thermoplastic dental splints (active control) protect against backscattered radiation from dental structures. Semi-individualized, 3D-printed tissue retraction devices (TRDs, study group) additionally spare healthy tissue from irradiation. MATERIALS AND METHODS: A total of 29 patients with head and neck cancer were enrolled in a randomized controlled pilot trial and allocated to receive TRDs (n = 15) or conventional splints (n = 14). Saliva quality and quantity (Saliva-Check, GC), taste perception (Taste strips, Burghart-Messtechnik), and oral disability (JFLS-8, OHIP-14, maximum mouth opening) were recorded before and 3 months after RT start. Radiotherapy target volume, modality, total dose, fractionation, and imaging guidance were case-dependent. To evaluate intra-group developments between baseline and follow-up, nonparametric Wilcoxon tests were performed. Mann-Whitney-U tests were applied for inter-group comparisons. RESULTS: At follow-up, taste perception was unimpaired (median difference in the total score; TRDs: 0, control: 0). No significant changes were found regarding oral disability. Saliva quantity (stimulated flow) was significantly reduced with conventional splints (median -4 mL, p = 0.016), while it decreased insignificantly with TRDs (median -2 mL, p = 0.07). Follow-up was attended by 9/15 study group participants (control 13/14). Inter-group comparisons showed no significant differences but a tendency towards a better outcome for disability and saliva quality in the intervention group. CONCLUSION: Due to the small cohort size and the heterogeneity of the sample, the results must be interpreted with reservation. Further research must confirm the positive trends of TRD application. Negative side-effects of TRD application seem improbable.

Influence of geometric dimensions on early failures of adhesively retained composite resin core build-ups.

OBJECTIVE: To determine the influence of the geometric dimensions of core build-ups on early core build-up failure, that is, loss before definitive prosthesis cementation. MATERIALS AND METHODS: Adhesive core build-ups of exclusively vital teeth in 114 participants were evaluated (n materials: 40 Rebilda DC, 38 Multicore Flow, 36 Clearfil DC Core; n teeth: 8 incisors, 54 premolars, 52 molars). Impressions of the abutment teeth were made (1) after removal of insufficient restorations/caries and (2) after core build-up and preparation for a fixed prosthesis. Digitized model surfaces of both situations were aligned (Geomagic Design X) and core build-up volume (VCBU ), remaining hard tissue volume (VAbut ), and size of the adhesive surface (Aadh ) were assessed. The derived measure dCBU  = VCBU /Aadh can be interpreted as mean arithmetic core build-up thickness. Associations between participant or core build-up design characteristics and the occurrence of early failures were statistically evaluated (SPSS v27, α = 0.05). RESULTS: A total of six (5.3%) core build-up failures were registered. Higher participant age, greater core build-up volume VCBU and greater arithmetic uniform thickness dCBU were associated with a greater incidence of failure in bivariate and univariate, however, not in multivariate statistics. CONCLUSIONS: Core build-up volume and thickness were associated with early success or failure. CLINICAL SIGNIFICANCE: In the case of voluminous/thick core build-ups in relation to the adhesive surface, additional measures, such as the preparation of retentive elements to increase the bonding area, might be considered to reduce the risk of early core build-up failure.

Head and Neck Pain Drawing Area Correlates With Higher Psychosocial Burden But Not With Joint Dysfunction in Temporomandibular Disorders: A Cross-Sectional Study.

Head and neck pain drawings have been introduced as part of the diagnostic gold standard for temporomandibular disorders (TMD). We aimed to quantify the spatial extent of pain in TMD patients and to analyze its association with further clinical findings. In a cross-sectional study, 90 patients (median age = 38 years; n women = 68) were diagnosed according to the DC/TMD. Intra-articular disorders were either confirmed or rejected by magnetic resonance imaging. The patients shaded all painful areas in a sketch of the left and right side of a face. A grid template was placed over the drawings and each region that contained markings was scored as painful. The correlation between the calculated area and the psychosocial variables (DC/TMD axis II) as well as the influence of pain lateralization were investigated using Spearman correlation, Mann-Whitney-U and chi-square tests. Pain affected all facial areas but concentrated on the regions of the temporomandibular joint and masseter origin. Thirty-nine percent reported purely unilateral pain, which was associated with structural TMJ findings in 77% of cases. Individuals with bilateral pain and those with greater spatial spread of pain had significantly higher scores on all axis II variables, except for functional limitation of the jaw. PERSPECTIVE: Head and neck pain drawings can contribute to a stratification of TMD patients. A greater extent of pain as well as pain bilateralization is associated with higher levels of emotional distress, pain chronicity and somatization, but not with functional impairment. Unilateral reporting of pain is associated with more intra-articular disorders.

Reliability and accuracy of intraoral radiography, cone beam CT, and dental MRI for evaluation of peri-implant bone lesions at zirconia implants - an ex vivo feasibility study.

OBJECTIVES: To determine the reliability and accuracy of intraoral radiography (IR), cone-beam-computed tomography (CBCT), and dental magnetic resonance imaging (dMRI) in measuring peri­implant bone defects around single zirconia implants. METHODS: Twenty-four zirconia implants were inserted in bovine ribs with various peri­implant defect sizes and morphologies. True defect extent was measured without implant in CBCT. Defects were measured twice in IR, CBCT, and dMRI with the inserted implant by three experienced readers. Reliability was assessed by ICC, accuracy by the Friedman test, and post-hoc-Tukey's test. RESULTS: A comparable good to excellent intra- and inter-reader reliability was observed for all modalities (intra-/inter-rater-CC range for IR; CBCT; dMRI: 0.81-0.91/0.79;0.87-0.97/0.96;0.87-0.95/0.94). Accuracy was generally high, with mean errors below 1 mm in all directions. However, measuring defect depth in the mesiodistal direction was significantly more accurate in dMRI (0.65 ± 0.38 mm) compared to IR (2.71 ± 1.91 mm), and CBCT (1.98 ± 1.97 mm), p-values ≤ 0.0001 respectively ≤ 0.01. CONCLUSIONS: Osseous defects around zirconia implants can be reliably measured in IR/CBCT/dMRI in the mesiodistal directions. In addition, CBCT and dMRI allow assessment of the buccolingual directions. dMRI provides a comparable accuracy in all directions, except for the mesiodistal defect depth, where it outperforms IR and CBCT.

Fit of anterior restorations made of 3D-printed and milled zirconia: An in-vitro study.

OBJECTIVES: To evaluate the fit of zirconia veneers made by either 3D printing or milling. METHODS: A typodont maxillary central incisor was prepared for a 0.5-mm-thick veneer and was reproduced 36 times from resin. Restorations were designed with a 20-µm-wide marginal and a 60-µm-wide internal cement gap, and were made from 3D-printed zirconia (LithaCon 3Y 210, Lithoz, n = 24) and milled zirconia (Cercon ht, DentsplySirona, n = 12). For milled zirconia, a drill compensation was needed to give the milling bur access to the intaglio surface. The restorations were cemented, cross-sectioned, and the cement gap size was analyzed by two raters. Inter-rater reliability was studied at 12 3D-printed veneers (intraclass correlation coefficient, ICC, mixed model, absolute agreement). Twelve remaining 3D-printed restorations were compared with 12 milled restorations regarding fit at three locations: marginally, labially, and at the incisal edge (Mann-Whitney U-tests, α<0.05). RESULTS: Inter-rater reliability was excellent, with an ICC single-measure coefficient of 0.944 (95%-confidence interval: [0.907; 0.966]). Gap sizes (mean ± SD / maximum) were 55 ± 9 / 143 µm at the margins, 68 ± 14 / 130 µm labially, and 78 ± 19 / 176 µm at the incisor edge for 3D-printed veneers. For milled veneers, gap sizes were 44 ± 11 / 141 µm at the margins, 85 ± 19 / 171 µm labially, and 391 ± 26 / 477 µm at the incisor edge. At the margins, the milled veneers outperformed the 3D-printed restorations (p = 0.011). The cement gap at the incisor edge was significantly smaller after 3D printing (p < 0.001). CONCLUSIONS: 3D-printed zirconia restorations showed clinically acceptable mean marginal gaps below 100 µm. Because drill compensation could be omitted with 3D printing, the fit at the sharp incisal edge was significantly tighter than with milling. CLINICAL SIGNIFICANCE: The fit of 3D-printed ceramic anterior restorations meets clinical standards. In addition, 3D printing is associated with a greater geometrical freedom than milling. With regard to fit this feature allows tighter adaptation even after minimally invasive preparation.

Nonsurgical treatment of class III malocclusion with temporomandibular disorder comorbidity: A clinical report.

The treatment of a 57-year-old woman with combined skeletal and pseudo-class III malocclusion who was also suffering from chronic myofascial orofacial pain is described. The challenge was to treat the patient's malocclusion while simultaneously managing the temporomandibular disorder. After a successful 3-month occlusal device therapy, which substantially reduced the patient's discomfort, a nonsurgical therapy by using complete-mouth fixed restorations was planned. The treatment was first tested by using printed interim restorations before monolithic zirconia restorations were provided. Stable occlusion and a pain-free outcome were observed at the 3-month follow-up.