STATEMENT OF PROBLEM: Prosthesis fit is 1 of the main factors influencing the success and survival of an implant-supported screw-retained restoration. However, scientific validation of the performance of engaging and nonengaging components in a fixed partial denture (FPD) and the effect of their combinations on the fit of FPDs is lacking. The screw resistance test has been used for the fit assessment of screw-retained FPDs. However, objective assessments by using analog and digital devices are now available.

PURPOSE: The purpose of this in vitro study was to investigate the effect of engaging and nonengaging components on the fit of screw-retained frameworks, supported by 2 conical connection implants with simulated vertical and horizontal misfits, by performing 2 different screw resistance tests (analog and digital).

MATERIAL AND METHODS: Thirty 2-implant-supported bar-shaped zirconia frameworks cemented on two 2-mm titanium bases were fabricated and divided into 3 groups (n=10) according to different abutment combinations: both engaging, engaging and nonengaging, both nonengaging. The fit of each framework was tested on the control cast and on 6 definitive casts simulating 50-, 100-, and 150-μm vertical and 35-, 70-, and 100-μm horizontal misfit levels. The abutment screws were tightened on each implant, and the screw rotation angle was measured both digitally, with a custom-made digital torque wrench and a computer software program, and conventionally, with an analog torque wrench and protractor. Clearly ill-fitting specimens were excluded. The data were statistically analyzed by 1-way analysis of variance (ANOVA) and the Tukey post hoc test (α=.05).

RESULTS: Both engaging specimens on the 100-μm horizontal misfit group and on all vertical misfit groups were clearly ill-fitting and excluded. Statistically significant differences among groups with different combinations of abutments were found (P<.05). The engaging abutments had a higher angle of rotation than the nonengaging abutments on all casts. In the horizontal misfit group, both engaging specimens had the highest angle of rotation, followed by engaging and nonengaging and both engaging specimens. In the vertical misfit group, the engaging and nonengaging specimens had the highest angle of rotation on the side of the engaging abutment. The angle of rotation increased with the increasing level of misfit.

CONCLUSIONS: Both nonengaging frameworks showed superiority in misfit tolerance, as the angle of rotation was lower than that of the engaging and nonengaging and both engaging frameworks. Conventional and digital torque wrenches showed similar results.

STATEMENT OF PROBLEM: The fit of implant-supported prostheses plays an important role in their mechanical and biological stability. Clinically, the prosthetic fit is typically assessed radiographically, but this method relies on the operator's subjective evaluation. Whether available digital tools could optimize the evaluation of the prosthetic fit is uncertain.

PURPOSE: The purpose of this in vitro study was to evaluate the influence of an image processing program on the radiographic detection of discrepancies in the active and passive fit of implant-supported prostheses. Two-implant-supported screw-retained prostheses were analyzed by simulating the vertical and horizontal misfits of 3 different implant abutment configurations.

MATERIAL AND METHODS: Seven casts were fabricated using 2 internal-connection titanium implants: 1 control; 3 with vertical (V) misfit of 50 µm, 100 µm, 150 µm; and 3 with horizontal (H) misfit of 35 µm, 70 µm, 100 µm. Thirty bar-shaped zirconia frameworks were fabricated and divided into 3 groups (n=10) according to their attachment to 2 engaging (E-E), 2 nonengaging (NE-NE), and engaging and nonengaging (E-NE) titanium bases. Digital parallel periapical radiographs were made of each specimen in the passive and active fit situation on each cast (1-screw test), except for the E-E specimens, which were only seated on the control, H35, and H70 casts because the fit on the remaining casts was poor. The mean gray value (MGV) was measured at the chosen regions of interest on the second implant (side B) using the ImageJ software program. Differences in the MGV measurements between the passive and active conditions were tested using a t test (α=.05) and compared the different misfit levels using analysis of variance (1-way ANOVA), followed by the Tukey HSD test (α=.05).

RESULTS: The highest values for the differences between passive and active fit were found for the V150 and H100 misfit simulations (P<.05). Statistical differences between the MGVs were found with some exceptions: the smallest simulated misfits (H35 and V50) revealed statistically significant MGV differences from the highest simulated misfits (V150, H100) and from the H70 in the groups where an engaging component was present (P>.05). In the horizontal misfit group of NE-NE abutment configuration, H70 revealed no significant difference from the control group cast (P>.05).

CONCLUSIONS: Measuring MGV differences between passive and active fit could be a promising alternative for detecting 70- to 150-µm gaps in the implant-abutment connection that result from the misfit. However, the procedure was not adequate for detecting <50 µm gaps, cannot be uniformly applied to all types of implant-abutment connections, and requires 2 exposures to X-radiation.

PURPOSE: To evaluate the survival rate of full-coverage tooth-supported fixed prosthetic restorations, single crowns (SCs), and fixed dental prostheses (FDPs), taking into consideration the potential influence of tooth-vitality, presence and type of post, and type of prosthetic restoration material.

MATERIALS AND METHODS: In October 2022, two authors independently conducted a search in PubMed, Web of Science, and Scopus electronic databases as well as a hand search to identify clinical human studies on full-coverage SCs and FDPs supported by vital and/or non-vital abutments and/or a combination of both, with a minimum observation period of 24 months.

RESULTS: Out of 4198 studies identified through the database search and 22 through hand searching, 26 studies fulfilled the inclusion criteria and were included in the analysis of the present systematic review. Included studies scored six points and more according to Newcastle-Ottawa Scale (NOS). The highest estimated 5-year survival rate was observed for (metal-ceramic and all-ceramic) SCs on vital teeth (98.3%; 95% CI [98.1, 98.6%]) and all ceramic SCs on non-vital teeth with fiber post (95.0%; 95% CI [94.5-95.4%]). Metal-ceramic SCs on vital teeth (97.1%; 95% CI [95.6-98.7%]) showed a statistically significant higher estimated 5-year survival rate compared to metal-ceramic SCs with cast metal post (90.7%; 95% CI [87.4-94.0%], P < 0.001), fiber post (91.3%; 95% CI [90.9-91.6%], P < 0.001) and without post (85.7%; 95% CI [80.7, 90.6%], P < 0.032). All-ceramic SCs with fiber post had a statistically significant higher estimated 5-year survival rate (95.0%; 95% CI [94.5-95.4%]) compared to metal-ceramic SCs on non-vital teeth with fiber post (91.3%; 95% CI [90.9-91.6%], P < 0.001). SCs (all-ceramic and metal-ceramic) with fiber post had a statistically significantly higher estimated 5-year survival rate of (92.7%; 95% CI [92.4-92.9%]) than SCs made of metal-ceramic and retained by cast metal post (90.7%; 95% CI [87.4-94.0%], P < 0.001). For FDPs, the 5-year survival rate was significantly higher for FDPs on vital abutments (84.9%; 95% CI [75.9, 93.9%]) compared to FDPs retained by non-vital abutment/s (81.3%; 95% CI [80.3, 82.2%], P = 0.049) irrespective to presence, type of post, and FDPs material. The results are limited by the limited number of studies and the presence of uncontrolled confounding clinical variables.

CONCLUSIONS: Within the limitations of the study, tooth vitality is suggested to contribute positively to the survival of SCs and FDPs.

OBJECTIVE: The aim of this study was to evaluate the influence of combining primers and cements from two different resin cement systems on the microtensile bond strength (muTBS) between zirconia and human dentin.

MATERIALS AND METHODS: A total of 120 specimens of zirconia cemented to dentin were allocated into eight groups based on cement type (RelyX Ultimate or Panavia V5) and primers (Tooth Primer, Clearfil Ceramic Primer and Scotchbond Universal Adhesive) combinations, applied to dentin or ceramic surfaces. Following artificial aging with 5000 thermocycles, muTBS tests were conducted. Statistical analysis was performed using One-way ANOVA and Tukey's post hoc tests (p </= 0.05), and failure modes were assessed.

RESULTS: The Panavia V5 cement system demonstrated the highest bond strength (19.4 +/- 4.4 MPa), significantly higher than the other groups except when RelyX cement was used with Panavia primers (16.9 +/- 3.7 MPa). Cohesive fractures within the cement layer were the predominant failure mode.

CONCLUSIONS: The combination of primers from different adhesive cement system brands may significantly affect the bonding effectiveness. Therefore, using products from a single product line of the same adhesive cement system, and following the manufacturer's recommendations for indications and use, is crucial for a more predictable clinical outcome.

Aim: This study aimed to evaluate the bond strength of adhesively cemented lithium disilicate restorations to dentin by applying different pretreatments and cleaning methods.

Material and Methods: Twenty-five human posterior teeth were mounted in an acrylic mold, flattened to expose mid-coronal dentin, and divided into five groups based on different pretreatments and cleaning methods prior to adhesive cementation. After cementation, the teeth were sectioned to obtain 1 mm² specimens, yielding 15 specimens in each group that were subjected to aging and thermocycling process, followed by a microtensile bond test and failure mode assessment.

Results: The highest bond strength values were in the control group and in the group that was treated with fluoride and where the temporary cement was removed using pumice, whereas the lowest values were in groups that were cleaned by excavator irrespective of whether they were treated with fluoride or not. However, all groups showed mainly cohesive failure without any statistically significant differences.

Conclusions: To eliminate any possible negative impact of eugenol on adhesion to dentin, surface cleaning by rotational brush and pumice is recommended prior to cementing lithium disilicate restorations.

Background: The aim of this study was to investigate how different scanning protocols affect the accuracy (truenessand precision) of intraoral scanning of complete arches with implant cylinders.Material and Methods: A master model was designed with five cylinders. One scanner, TRIOS2 (3shape), was usedto scan the model with four different scan protocols: ROCK (wavelike scanning in a pendulum movement), ZIG-ZAG (wavelike scanning technique), OBP (occlusal, buccal, and palatal), and OWBP (occlusal, wiggling, buccal,and palatal). A total of 30 scans were performed using each of the four protocols. The master model was digitizedwith an industrial ISO-certified ATOS scanner. GOM inspect software was used to compare the scans to the mastermodel and evaluate any deviation between the scan protocols and the master model. The data was analyzed usingthe One Sample t-test (p=0,05).Results: The precision (standard deviation) ranged from 23-83μm for protocol ROCK, 22-147μm for ZIGZAG,21-170μm for OBP, and 23-116μm for OWBP. The trueness (mean deviation from master model) was 5-41μm forROCK, 7-97μm for ZIGZAG, -21-29μm for OBP, and 1-24μm for OWBP. All protocols showed statistically signi-ficant differences to the master model in multiple distances, except OWBP, which had a single significant differencein comparison to the master model.Conclusions: Protocol OWBP has a higher trueness than other tested protocols. All tested protocols have highertrueness and precision when scanning smaller distances than inter-arch measurement. Clinical significance;Thetrueness and precision of intraoral scanning is generally better in smaller spans due to less deviation. The protocolOWBP, that is recommended by the manufacturer, has the least deviating trueness in comparison to the mastermodel.

Purpose: To assess and compare the clinical outcomes of three different types of all-ceramic posterior monolithic tooth-supported crowns. Materials and Methods: A total of 71 patients received 90 all-ceramic crowns randomized to be either high-translucency zirconia (ZC), high-translucency zirconia with a partial buccal veneer (ZC-V), or lithium disilicate glass-ceramic (LDS). All treatments were performed by four general dentists. Choice of material was blinded. Baseline and subsequent annual evaluation were based on modified California Dental Association (CDA) criteria. A questionnaire was used to include patient-reported outcomes and to compare them to the crown quality rating performed by dentists. Results: A total of 66 patients with 84 crowns were examined after 3 years. The survival rate was 98.8%. No crowns fractured during the observation period. One ZC-V crown failed due to loss of retention, and three complications were noted: loss of retention occurred in one ZC crown, and two ZC crowns needed to be endodontically treated. There was no significant difference between the different crowns regarding marginal integrity, surface, or anatomical form. Both patients and examining dentists rated the crowns favorably regarding esthetics, patients more than dentists. Conclusion: Posterior lithium disilicate glass-ceramic crowns and translucent zirconia crowns with or without a partial buccal veneer show excellent and promising clinical outcomes from a short-term perspective. Patients and dentists rate the restorations favorably concerning esthetics and function.

Because new zirconia materials are constantly being developed, the aim was to identify and qualitatively synthesize research on how processing and time-related factors affect the properties of high translucent (HT) zirconia intended for monolithic restorations. Cochrane Library, PubMed, Scopus, Web of Science, and reference lists were searched for in vitro and clinical studies. Eligibility and risk of bias were assessed. A synthesis of 142 publications was performed. HT 3Y-TZP was the most common, followed by 5YSZ, 4YSZ, and multilayer. In the laboratory, HT 3Y-TZP should be sintered according to the manufacturer’s recommendation and polished before glazing to favour strength, roughness, and wear behaviour. In the clinic, polishing is necessary after grinding to favour roughness and aging resistance. Over time, when using hydrothermal aging, t–m phase transformation and reduced translucency are expected, without affecting the strength and roughness. The strength of 4YSZ and 5YSZ is unaffected. However, the time-related methods are of questionable clinical significance. The evidence of all other factors’ effects on the properties of HT zirconia is lacking or limited; thus, these factors are of relevance for future research. There is a high heterogeneity of study designs and methods, and the results are brand-dependent.

PURPOSE: To assess the influence of several factors on the survival of tooth-supported fixed partial dentures (FPDs) with vital and non-vital abutments.

MATERIALS AND METHODS: The present retrospective cohort study was based on the records of patients treated with 3-to-7-unit tooth-supported FPDs with a minimum follow-up time of 6 months after prosthesis delivery. Cumulative survival rate (CSR) was calculated over the maximum follow-up period. Cox regression models were used to evaluate the association between the clinical covariates and prosthesis failure.

RESULTS: A total of 331 FPDs in 229 patients were included. The CSRs were 90.1% and 77.6% after 5 and 10 years and 67.9% and 52.1% after 15 and 20 years, respectively. Tooth-supported FPD failure was more prevalent within the first years of prosthesis delivery. Loss of one or more abutment teeth and loss of prosthesis retention were the main reasons for failure. Smoking and type of prosthesis material significantly influenced the survival of FPDs. Abutment vitality, position of the non-vital abutment, or prosthesis length did not show any significant influence on the occurrence of prosthesis failure.

CONCLUSION: Smoking and the type of prosthesis material are suggested to contribute to an increased rate of FPD failure irrespective of abutment vitality.

STATEMENT OF PROBLEM: The second most common biological complication in fixed prosthodontics is loss of pulp vitality, which may lead to restoration loss. While reasons for loss of pulp vitality are unclear, 2 potential contributing factors, duration of the interim restoration and operator experience, have not been fully investigated.

PURPOSE: The purpose of this retrospective study was to investigate whether the duration of the interim restoration or the experience of the dentist was correlated with loss of pulp vitality.

MATERIAL AND METHODS: Fixed prosthetic restorations placed between 2005 and 2012 were retrospectively analyzed. Abutment teeth supporting single-unti or multiunit restorations were evaluated regarding loss of pulp vitality. The Mann-Whitney U test and simple logistic regression were used, with α=.05 for the subsequent multiple logistic regression. The experience of dental professionals was defined by the number of treatments performed and coupled with failure rate by using an analysis of variance.

RESULTS: One hundred seventy-four dentists made 15 879 restorations, of which 1136 failed during the observation period, a failure rate of 7.2%. Two hundred fifty restorations were randomly selected from the failed restorations, and a corresponding 250 restorations were randomly selected from nonfailed restorations for the control group. Increased duration with interim replacement was linked to a higher risk of loss of pulp vitality (P<.001). Failure rate in the dentist group varied from 0% to 100%. No significant differences in failure rate were found among dentists who did few restorations and those who performed larger numbers of restorations.

CONCLUSIONS: The results of the present study suggest that operator experience does not affect failure rate. However, extended time with an interim restoration was a contributing factor to the loss of pulp vitality.