Evaluation of the clinical success of four different types of lithium disilicate ceramic restorations: a retrospective study

Background/purpose How long do lithium disilicate restorations last before they fail? The aim of this study was to assess the success rate of four different types of restorations made from lithium disilicate. Materials and methods A total of 87,203 ceramic restorations, classified into four different types (inlay or onlay, veneers (Vs), single crowns (SCs), and fixed partial dentures (FPDs)), were used. All were made of lithium disilicate (IPS e.Max CAD) with Cerec Inlab CAD/CAM system (Sirona Dental Systems, Bensheim, Germany). They were reported by dentists and entered in the database of the private B&R Dental Center between March 2015 and June 2020 and assessed retrospectively up to a period of 5 years based on the following parameters: failure rate and cause of failures (ceramic fracture, debonding, marginal adaptation, color match, endodontic intervention, periodontal disease, and secondary caries). Failure distribution according to gender, arch, and teeth type was also evaluated. The time-dependent time-to-failure/complication and their differences were calculated in months according to the Kaplan Meier and log-rank tests. The Chi-squared test (p 0.05) was used to assess the variations in causes of failure rates between different restorations. Results Kaplan Meier test showed overall cumulative survival probability of lithium disilicate restorations for up to years was 85.08%. Inlay/onlay and Vs ceramic restorations showed highest cumulative survival probability (99.4%, 98.6, respectively). FPDs had the least cumulative survival probability (52.9%) which was significantly (P < 0.00001) higher than for other ceramic restorations using the log-rank test. Moreover, overall time-dependent time-to-failure/complication occurred after 52.373 months according to Kaplan–Meier (CI: lower bound: 51.875 months; upper bound: 52.871 months). Ceramic fracture in both FPDs and SCs (27.6% and 26.6%, respectively) and debonding in Vs (12.7%) were significant as the main reasons for failure (P = 0.000). The failure rate was significantly higher for the maxillary arch than the mandibular arch (P = 0.021). Fracture and marginal discrepancy were more frequent in the molar region (77.5% and 14.75%, respectively) and significantly higher here than in the anterior and premolar regions (P = 0.000). Conclusion The medium-term performance of lithium disilicate is ideal. Ceramic fracture was the most common cause of failure in SCs and FPDs. FPDs presented with the highest failure rate based on evaluation for up to 5 years.

Challenges in Managing a Fractured Cement-retained Crown Located at the Aesthetic Zone: A Case Report

Implant prosthesis is a popular treatment modality but it is not complication free. This article discussed the management of a cemented, all-ceramic implant crown in the maxillary anterior region that had veneering ceramic fracture after three years in function. A screw-retained prosthesis was prescribed to avoid the show of the screw access channel on the incisal edge of the crown. This was achieved by changing the location of the screw hole using the angle screw channel that overcame the angulation issue.

The reasons for ceramic-on-ceramic revisions between the third- and fourth-generation bearings in total hip arthroplasty from multicentric registry data

This study aimed to evaluate (1) the overall reasons for first revision in CoC THAs; (2) whether the reasons for revision differ between third-generation and fourth-generation CoC THAs; and (3) the specific factors associated with bearing-related problems as the reason for revision. We retrospectively reviewed 2045 patients (2194 hips) who underwent first revision THA between 2004 and 2013, among which 146 hips with CoC bearings underwent revision. There were 92 hips with third-generation ceramic bearings and 54 hips with fourth-generation ceramic bearings. The major reasons for CoC THA revisions were ceramic fracture and loosening of the cup or stem. When ceramic fracture, squeaking, incorrect ceramic insertion, and unexplained pain were defined as directly related or potentially related to ceramic use, 28.8% (42/146) of CoC revisions were associated with bearing-related problems. Among the third-generation ceramic bearings, revision was performed in 41.3% (38/92) of cases owing to bearing-related problems whereas revisions were performed for only 7.4% (4/54) of cases with fourth-generation ceramic bearings owing to bearing-related problems (p < 0.001). Younger age, lower American Society of Anesthesiologists (ASA) grade, and preoperative diagnosis of osteonecrosis were factors related to CoC THA revisions due to bearing-related problems.

Arthroscopic evaluation and treatment of a squeaking hip. A case report

Background Squeaking of ceramic-on-ceramic total hip arthroplasty is an unexpected complication which occurs in 1- 30% of patients. Revision surgery is required in 0.2% of the cases, when a ceramic fracture is suspected, or in case of severe malposition of the implants, subluxation, or impingement. Hip arthroscopy may be a useful diagnostic and therapeutic option in squeaking hips. Case presentation A patient presenting with a pain-free squeaking underwent hip arthroscopy to examine the sliding surfaces and the rim of the acetabulum, and to search for signs of impingement. Thorough lavage and debridement of hip synovitis and fibrous tissue was performed. The squeaking noise immediately disappeared after the surgery. The patient was allowed to fully weight bear as tolerated with 2 crutches for 2 weeks. Two years after the arthroscopy, the patient remained symptom-free. Conclusions The potential reasons for hip squeaking in our patient are discussed. Hip arthroscopy may prove useful as a diagnostic and therapeutic option for some patients presenting with a squeaking ceramic-on ceramic hip replacement.

Effect of Deep Margin Elevation on CAD/CAM-Fabricated Ceramic Inlays

Clinical Relevance Using the deep margin elevation technique in preparations extending beyond the cemento-enamel junction appears to be beneficial in maintaining structural integrity of CAD/CAM-fabricated feldspathic ceramic inlays. SUMMARY Objective: To evaluate the effect of deep margin elevation on structural and marginal integrity of ceramic inlays. Methods and Materials: Forty extracted human third molars were collected and randomly separated into four groups (n=10/group). In group 1 (enamel margin group), the gingival margin was placed 1 mm supragingival to the cemento-enamel junction (CEJ). In group 2 (cementum margin group), the gingival margin was placed 2 mm below the CEJ. In group 3 (glass ionomer [GI] margin group), the gingival margin was placed 2 mm below the CEJ, and then the margin elevated with GI to the CEJ. In group 4 (resin-modified glass ionomer [RMGI] margin group), the gingival margin was placed 2 mm below the CEJ, and then the margin elevated with RMGI to the CEJ. Standardized ceramic class II inlays were fabricated with computer-aided design/computer-aided manufacturing and bonded to all teeth, and ceramic proximal box heights were measured. All teeth were subjected to 10,000 cycles of thermocycling (5°C/55°C) and then underwent 1,200,000 cycles of vertical chewing simulation at 50 N of force. Ceramic restorations and marginal integrity were assessed with a Hirox digital microscope. The Fisher exact test (two-tailed) with adjusted p-values (α=0.05) and logistic regression were used for statistical analysis. Results: The cementum margin group had a significantly higher ceramic fracture rate (90%) compared to other groups (10% in enamel margin and GI margin groups, p=0.007; 0% in RMGI group, p&lt;0.001). Logistic regression showed that with increased ceramic proximal box heights, the probability of ceramic fracture increased dramatically. Conclusion: Deep marginal elevation resulted in decreased ceramic fracture when preparation margins were located below the CEJ. There was no difference found between margin elevation with GI or RMGI. Increased heights of ceramic proximal box may lead to an increased probability of ceramic fracture.

Fracture load of nano-ceramic composite material for anterior endocrown restorations

Objective: To evaluate ability of Nano Ceramic Composite endocrown to withstand occlusal forces when used in the anterior region. Material and Methods: Eighty endodontically treated maxillary central incisors teeth were randomly divided into two main groups according to the restoration type. 40 of these teeth were post, core and crown restorations and 40 were endocrown restorations. Then they were divided by halves into two subgroups according to the material used 20 were made with Lava Ultimate and the other 20 with IPS e.max. Each subgroup was then further subdivided into two divisions according to the remaining tooth structure above the CEJ (n=10): 2 mm and 0.5 mm above the CEJ. After teeth preparation, the restorations were all made by CAD/CAM system (Cerec MCXL). All samples had undergone cyclic fatigue testing, and then loaded to fracture using a universal testing machine. The specimens were measured and statistically analyzed using Mann-Whitney test for comparing the mean changes between the groups. Results: Lava Ultimate showed higher mean fracture load values than IPS e.max specimens. Conclusion: Endocrowns were found to be more favorable when used on endodontically treated teeth than the conventional post, core and crown restorations.KEYWORDSEndocrowns; All-ceramic; Fracture; Cyclic loading.

Study on Thermally Induced Crack Propagation Behavior of Functionally Graded Materials Using a Modified Peridynamic Model

Peridynamic (PD) theory is used to study the thermally induced cracking behavior of functionally graded materials (FGMs). A modified thermomechanical peridynamic model is developed. The thermal crack propagation of a ceramic slab in quenching is calculated to validate the modified PD model. The results predicted by the modified PD model agree with previously published numerical and experimental ones. Compared with the original PD model, the calculation accuracy of the modified PD model for thermal cracking is improved. The thermal cracking in FGMs is also simulated. The effects of material shape, initial temperature, and ceramic fracture toughness on thermal crack propagation behaviors are studied. It can be found that the thermal cracks in FGMs are still in periodical and hierarchical forms. The metal materials in FGMs can prevent crack initiation and arrest the long cracks. The crack number tends to be increased with the increasing initial temperature, while the strengthened ceramic fracture toughness can decrease it.

Cementless total hip arthroplasty with delta-on-delta ceramic bearing in patients younger than 30 years

Background: Despite improvements in the mechanical properties of alumina ceramics, the outcome of total hip arthroplasty (THA) with contemporary ceramic bearings in young patients remains a matter of concern. We evaluated the results of cementless THA with the use of the delta ceramic bearing, and determined the prevalence of osteolysis, squeaking, and ceramic fracture in patients aged < 30 years at mid-term. Methods: From March 2008 to January 2012, 76 consecutive patients (91 hips), younger than 30 years, underwent cementless THA with Delta ceramic bearings. In each follow-up, the clinical evaluation including noise and radiological evaluations were recorded. Results: Among them, 72 patients (86 THAs) were followed-up for a minimum of 5 years (mean 70.8; 60−95.9 months). There were 44 men (47 hips) and 28 women (39 hips). The mean age at the time of the index arthroplasty was 25.9 (16−30) years and the mean preoperative Harris Hip Score (HHS) was 59.4 (23−79) points. HHS improved to 96.3 (64−100) points at the final follow-up evaluation. 8 hips (9.3%) exhibited grinding or squeaking. No hip had aseptic loosening and no hip was revised. No osteolysis was detected around any acetabular or femoral components. Conclusions: Our results suggest that cementless THA with the use of Delta ceramic bearing provides satisfactory results without osteolysis or ceramic fracture in patients aged <30 years at a mid-term follow-up. Clinical Trials.gov Protocol Registration System (trial no. NCT01838096).

A focused update on preventing ceramic fractures in hip arthroplasty

Ceramic bearings have several desirable properties, such as resistance to wear, hardness, and biocompatibility, that favour it as an articulating surface in hip arthroplasty. However, ceramic fracture remains a concern. We have reviewed the contemporary literature, addressing the factors that can influence the incidence of ceramic bearing surface fracture. Cite this article: Bone Joint J 2019;101-B:897–901.