OBJECTIVE: To evaluate the effect of different cement types on the incidence of failure and loss of retention of zirconia and metal-ceramic single crowns (SCs) cemented on implant abutments.
METHODS: We placed 567 implant-supported SCs in 358 patients and retrospectively evaluated long-term retention for up to 12.8 years. The frameworks were made from metal alloy (n = 307) or zirconia (n = 260). SCs were cemented with permanent (glass-ionomer cement; n = 376) or semipermanent cement (zinc oxide non-eugenol cement; n = 191) on standardized (n = 446) or customized (n = 121) abutments. Kaplan-Meier curves were used to calculate the incidence of decementation. Differences between survival curves were assessed with log-rank tests. Cox-regression analysis was performed to evaluate multiple risk factors.
RESULTS: Of the 567 SCs, 22 failed because of technical complications and four because of implant loss. Loss of retention was observed in 50 SCs. Analysis revealed a 7% probability of loss of retention for zirconia and 16% for metal-ceramic SCs after 10 years (p = .011). After 5 years, loss of retention was higher for standardized abutments than for customized abutments (p = .014). The probability of loss of retention was higher with semipermanent than with permanent cement (p = .001). Cox-regression analysis revealed semipermanent cement as the only significant risk factor for SC failure (p = .026).
CONCLUSIONS: In contrast to semipermanent cement, permanent cement provides acceptable long-term retention of cemented implant-supported SCs. These possible positive effects of customized abutments have to be controlled with larger sample sizes.

BACKGROUND: The purpose of this study was to conduct survival analysis of teeth following clinical crown lengthening procedures (CLPs) and crown insertions via a retrospective cohort study.
METHODS: Patient- and tooth-related data were collected from 268 participants who received CLPs from 2009 to 2015. The Kaplan-Meier curve and the log-rank tests were used to estimate the probability of survival and compare the survival probabilities among different variables. A Cox multivariate proportional hazard regression model was used to investigate the collective effects of root canal treatment (RCT) and the types of opposing dentition.
RESULTS: The rate of tooth loss was 21.6% during the observation period from 1 to 14 years, with 58 teeth extracted. The most attributable reason for tooth extraction was coronal tooth fracture, followed by endodontic failure such as root fracture. The survival probability was 0.87 at 5 years and 0.7 at 10 years. No significant differences in the survival probabilities were found among different providers and locations, the presence of a post, and the types of crowns. The hazard ratio for tooth loss was 6.3, 95% confidence interval (CI) [2.6 to 20.9] in the teeth with RCT (p < 0.001) and 2.4, 95% CI [1.1 to 4.8] in the teeth occluding implant-retained prostheses (p = 0.016).
CONCLUSIONS: Tooth loss following CLPs and crown insertions appeared least among the teeth without RCT when occluding natural teeth, while tooth loss was most among the teeth with RCT when occluding implants.

This systematic review evaluated the occlusal changes after loading with implant-supported single crowns.
An electronic literature search was conducted in PubMed, Embase and Cochrane library for randomized (RCTs) or non-randomized controlled clinical trials (CCTs), with a minimum of 10 patients.
Studies reporting the occlusal force changes on implant-supported single crowns - with natural teeth as antagonist - measured at baseline and after loading periods were included. 4 CCTs including 133 ISCs in posterior sites were included for meta-analysis. All analyzed ISCs had no contact at a light bite and a light contact at a heavy bite in MIP at loading (baseline).
The relative occlusal forces (ROFs) of each implant-supported single crown (ISC) or control tooth (CT) were extracted. ROFs were defined as percentage of the total occlusal force of the entire dentition at maximum intercuspal position (MIP). A meta-analysis was conducted to compare the ROF changes at different follow-up periods and the weighted mean differences in ROF between ISCs and CTs were pooled and analyzed. The amount of change in ROF was significantly lower in 6 to 12 months after loading comparing the follow-up period between baseline and 6 month (p < 0.05). At baseline and 3-month follow-up, CTs presented significant higher ROF than ISCs (p < 0.05), while no significant difference was found after half year following.
This study showed that the ROF changes significantly over time after loading of ISCs. It might prove that the occlusal concept defined at the time of prosthetic delivery changes or adapts naturally over time.
The function of specific implant occlusal concept (no contact at a light bite and a light contact at a heavy bite in MIP) is limited over time and careful monitoring and occlusal adjustments should be recommendable during the first-year follow-up.

UNASSIGNED: Translucent monolithic zirconia restorations have recently introduced. The purpose of this study was to evaluate the clinical behavior and the survival rate of the posterior third-generation monolithic zirconia crowns (MZCs) during three years of clinical service.
UNASSIGNED: Twenty-four patients who needed thirty crowns were enrolled in this study. Digital impressions were made, and the crowns were milled and cemented with a resin cement. The crowns outcomes were assessed using the California Dental Association\'s (CDA) criteria. Gingival index (GI), plaque index (PI), and periodontal probing depth (PPD) for MZCs and contralateral natural teeth (control) were assessed. Margin index (MI) for MZCs was also assessed. Data analysis was conducted using the Wilcoxon signed-rank and the Friedman tests.
UNASSIGNED: The 3-year survival rate was 100%. All MZCs were rated as satisfactory throughout the follow-up period, and no biological or mechanical complications were observed. No differences were recorded when GI, PI and PPD at 3-year of follow-up were compared to baseline. No differences were recorded between crowned and control teeth. The MI remained stable throughout the study period.
UNASSIGNED: The third-generation monolithic zirconia appears to be a good treatment option for the rehabilitation of posterior single teeth.

BACKGROUND: The objective of the study was to retrospectively assess the clinical performance of dental prostheses, single crowns, and three-unit bridges to identify clinical biological and mechanical complications in the Ha\'il province of Saudi Arabia.
METHODS: The study was conducted between March 2021 to October 2021 and included 421 patients who underwent crown and tooth-supported fixed partial denture (FPD) procedures at the Dental Polyclinics Center in the Ha\'il region of Saudi Arabia from 2010-2020. The planned sampling approach was applied. Patients who underwent crown and FPD placements at the dental center within the scheduled period were identified through clinical assessments. The inclusion criteria were met by patients with three-unit FPDs and a single crown containing a natural contralateral tooth or teeth. A total of six general dentists conducted clinical exams. Patient satisfaction and technical and biological issues were the evaluation criteria for crowns and FPDs. The frequency and percentage of the various characteristics employed in the current investigation were ascertained using cross-tabulation. The Chi-square test was employed to assess the associations between categorical variables, with p-values ≤ 0.05 considered significant.  Results: Marginal integrity was recorded in 332 participants (78.9%), which was satisfactory for the majority of the restoration. The acceptance morphology was present in 252 (59.9%) restorations. The highest rate of the restorations 274 (66.2%) had satisfactory color. In 86 cases (20.4%), there was visible periodontal depth of at least 5 mm. Three hundred and six (72.7%) of the fixed restorations had gingival bleeding connected to them, and 96 (22.8%) teeth had periapical lesions. A total of 311 patients (73.9%) reported they were satisfied with their fixed restorations.
CONCLUSIONS: The technical and biological complications noted in the current study were not higher compared with other studies of crowns and fixed dental prostheses. The majority of patients were satisfied with the restoration.

OBJECTIVE: The purpose of this systematic review and meta-analysis is to evaluate the marginal adaptation of single unit full coverage lithium disilicate fixed dental restorations fabricated with the conventional heat pressed technique and the digital CAD/CAM workflow.
METHODS: This study is according to the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) statement. study research was conducted in MEDLINE via PubMed and Cochrane Library databases together with a hand search of studies published until June 2022. The search terms were combining suitable Medical Subject Headings (MeSH terms) together with free text words in single or multiple conjunctions. A modified methodological index was used to assess the risk of bias of the included studies. A random effect model was applied to pool the effect estimates, and further assessment of the heterogeneity across studies using the Q test and the I2 metric was conducted. All statistical analyses were performed using Rstudio software, version 4.1.2, using the \'meta\' package.
RESULTS: The electronic search and hand search identified 51 articles. Eighteen met the inclusion criteria and were included in the systematic review, 17 of which were in vitro and only one was an in vivo study. However, 17 of the initial 18 could be included in the meta-analysis, due to lack of statistical data in one of the in vitro studies. Statistical analyses were conducted by using the Rstudio software program. Meta-analysis was performed with the random effects model (α=.05). No statistical difference was found between the two fabrication methods (p-value=0.49).
CONCLUSIONS: Although the mean marginal adaptation of lithium disilicate single crowns was found to be better with the heat-pressed technique, there was no statistical significance with the CAD/CAM fabricated restorations and both resulted in a clinically acceptable result. Nonetheless, more clinical studies are needed for safer conclusions.

UNASSIGNED: The digital impression is a promising technique in prosthodontic treatment. However, the influencing factors of patient comfort is lacking, and the evidence of crown quality is mostly based on in vitro studies. The purpose of this double-blinded clinical trial was to compare the patient satisfaction and crown accuracy of two different intraoral scanners (IOSs) for the fabrication of all-ceramic single crowns (SCs).
UNASSIGNED: Participants in need of posterior tooth-supported SCs were enrolled. Each patient received quadrant scan by both the Metal Industries Research and Development Centre (MIRDC) IOS and Carestream CS3500 in a random sequence. After scanning, participants had to fill in a 6-item perception questionnaire that based on 5-point Likert scale for two IOSs. Both data were sent to a dental laboratory to fabricate the monolithic lithium disilicate SCs. The crown accuracy including marginal fit, proximal contact, occlusal contact, and general satisfaction were accessed based on 5-point scale.
UNASSIGNED: A total of 15 participants with 40 crowns (20 SCs in each group) were investigated. Regarding to patient satisfaction, there was no statistically significant difference in total score between MIRDC and Carestream IOSs (23.6 ± 3.79 vs 23.1 ± 4.28, P = 0.36). In terms of crown accuracy, there was significantly different in total score and all the evaluated parameters between MIRDC and Carestream groups (6.1 ± 1.41 vs 13.3 ± 3.75, P < 0.001).
UNASSIGNED: Both MIRDC and Carestream IOSs can provide good patient satisfaction during intraoral scanning. The Carestream IOS obtains better accuracy for the fabrication of all-ceramic SCs.

The aim of this present record-based retrospective study was to investigate the influence of the crown-implant ratio (CIR) and implant inclination in relation to the occlusal plane on the marginal bone loss (MBL) around dental implants supporting single crowns in the posterior region of the jaws. All the cases of implant-supported single crowns in the premolar and molar regions were initially considered for inclusion. Only implants not lost, with baseline radiographs taken within 12 months after implant placement and with a minimum of 36 months of radiological follow-up, were considered for the analysis of MBL. Univariate linear regression models were used to compare MBL over time between 12 clinical covariates, after which a linear mixed-effects model was built. After the exclusion of 49 cases, a total of 316 implant-supported single crowns in 234 patients were included. The results from the statistical models suggested that implant inclination and anatomical- and clinical CIR (the main related factors investigated in the study) were not statistically significantly related to MBL over time. Age (older people), tooth region (premolar), and bruxism (bruxers) had a statistically significant influence on MBL over time.

OBJECTIVE: To investigate the clinical performance of chairside fabricated tooth-supported posterior single crowns from lithium disilicate ceramic.
METHODS: Thirty-four crowns (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein) were inserted between 2006 and 2007 and again evaluated after 15 years. Survival and success rates were calculated according to Kaplan-Meier, and the quality of the crowns was evaluated by using modified United States Public Health (USPHS) criteria.
RESULTS: Twenty-two crowns were available for recall; six patients were defined as dropouts. The mean observation period was 15.2 years (± 0.2). Six failures occurred (1 technical/5 biological) resulting in a survival rate of 80.1%. The success rate was 64.2%. The roughness of the crowns increased (p = 0.021) and the majority of adhesive gaps were discolored (p = 0.001) in comparison to baseline. The color, tooth, and crown integrity remained stable over the follow-up period (p ≥ 0.317).
CONCLUSIONS: The fabrication of tooth-supported lithium disilicate crowns using a chairside approach yielded acceptable long-term survival and success rates. Due to discoloration, the long-term use of dual-cure self-adhesive resin cements might result in unpleasing esthetic results.
CONCLUSIONS: The performance of posterior lithium disilicate single crowns revealed excellent to good clinical quality and an acceptable number of events after 15 years of clinical service.

OBJECTIVE: This in vitro study evaluated the fracture strength of screw-retained zirconia crowns connected to zirconia (Zr) and titanium (Ti) implants after undergoing a simulation of 5 years of clinical use.
METHODS: Forty-eight screw-retained zirconia crowns were fabricated and assembled on four implant systems, with 12 in each group: (1) Zr implant (pure ceramic; Straumann AG) (PZr); (2) Zr implant (NobelPearl; Nobel Biocare) (NPZr); (3) Ti-Zr implant (Bone Level Roxolid; Straumann AG) (RSTiZr); (4) Ti implant (Conical Connection PMC; Nobel Biocare) (NRTi). Crowns were luted to their associated abutments using resin cement and then torqued to their assigned implants at the recommended torque value. Specimens were subjected to dynamic loading for 1,200,000 loading cycles. Fracture strength, measured in Newtons (N), was tested under static compression load using a universal testing machine at an angle of 30°. One-way ANOVA and Tukey\'s multiple comparisons post hoc test were used to compare the mean fracture values between the groups at a significance level of 0.05.
RESULTS: The average fracture strengths for the RSTiZr and NRTi groups were 1207 ± 202 and 1073 ± 217 N, respectively, which was significantly (p < 0.0001) higher than the PZr and NPZr groups (712 ± 76 and 571.6 ± 167 N, respectively). However, no significant difference was found between the fracture strength value of RSTiZr and NRTi (p = 0.260) or PZr and NPZr (p = 0.256) groups.
CONCLUSIONS: Zirconia crowns connected to Zr implants have the potential to withstand the average physiological occlusal forces which occur in the anterior and premolar regions.