Clinical research on restorations using CAD/CAM-fabricated monolithic zirconia endocrowns and post and core crowns after up to 5 years.

OBJECTIVE: To assess the clinical status of monolithic zirconia CAD/CAM endocrowns and crowns on post and core buildups in endodontically treated molars after 5 years of clinical service. MATERIALS AND METHODS: A total of 670 patients who received restorations for excessive defects at Ansteel Group Hospital from 2012 to 2015 were selected and randomly divided into two groups: 334 patients in the endocrown group and 336 in the post and core crown group. All the treatments were performed using a digital CAD/CAM system. The prostheses restorations at 1, 3, and 5 years after treatment were evaluated using the USPHS (United States Public Health Service) criteria and satisfaction questionnaire. In addition, the time cost of tooth preparation was recorded by the clinicians. RESULTS: Most of the patients in both groups reported grade A at the after-treatment follow-ups. Gingival health, food impaction, marginal accuracy, and general satisfaction at 3 and 5 years after treatment in the endocrown group rated higher (P < 0.05) than in the post and core crown group. There was no statistical difference in other indicators between the two groups at all observational after-treatment timepoints (P > 0.05). The time cost of tooth preparation in the post and core crown group was significantly higher than that in the endocrown group. CONCLUSION: A CAD/CAM scanning system combined with a monolithic zirconia endocrown restoration was rated very positively by the participants. Endocrown restorations are a significantly superior choice compared with post and core crowns in clinical application. (Int J Comput Dent 2022;25(3):287-294; doi: 10.3290/j.ijcd.b2599661).

Clinical performance of CAD/CAM-fabricated monolithic zirconia endocrowns on molars with extensive coronal loss of substance.

OBJECTIVE: To clinically evaluate computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated molar endocrowns after 6 months and 1, 2, and 3 years of clinical service. MATERIALS AND METHODS: 289 patients with 321 molars (267 patients with one endocrown, two patients with two endocrowns, and ten patients with three endocrowns) exhibiting extensive coronal loss of substance participated in the study. Endocrown preparations were scanned, and endocrowns designed and machined with the Cerec CAD/CAM system. The endocrowns were adhesively seated using a composite luting agent, and assessed using clinical United States Public Health Service (USPHS) criteria at baseline, 6 months, and 1, 2, and 3 years after placement. Patient satisfaction was evaluated using a questionnaire. RESULTS: None of the 289 endocrowns failed during the observation period. The high clinical rating criteria (97.2%) and the high satisfaction percentage (98.0%) remained practically unchanged (P > 0.05) throughout the follow-up assessments at 6 months and after 1, 2, and 3 years. CONCLUSION: Monolithic zirconia endocrown restorations represent an effective method of restoring posterior teeth after root canal therapy. Based on the short-term observation period of the present study, monolithic zirconia endocrowns can be considered a reliable restoration for endodontically treated molars with extensive coronal loss of substance.

CAD/CAM machining Vs pre-sintering in-lab fabrication techniques of Y-TZP ceramic specimens: Effects on their mechanical fatigue behavior.

This study evaluated the effects of different pre-sintering fabrication processing techniques of Y-TZP ceramic (CAD/CAM Vs. in-lab), considering surface characteristics and mechanical performance outcomes. Pre-sintered discs of Y-TZP ceramic (IPS e.max ZirCAD, Ivoclar Vivadent) were produced using different pre-sintering fabrication processing techniques: Machined- milling with a CAD/CAM system; Polished- fabrication using a cutting device followed by polishing (600 and 1200 SiC papers); Xfine- fabrication using a cutting machine followed by grinding with extra-fine diamond bur (grit size 30 µm); Fine- fabrication using a cutting machine followed by grinding with fine diamond bur (grit size 46 µm); SiC- fabrication using a cutting machine followed by grinding with 220 SiC paper. Afterwards, the discs were sintered and submitted to roughness (n=35), surface topography (n=2), phase transformation (n=2), biaxial flexural strength (n=20), and biaxial flexural fatigue strength (fatigue limit) (n=15) analyses. No monoclinic-phase content was observed in all processing techniques. It can be observed that obtaining a surface with similar characteristics to CAD/CAM milling is essential for the observation of similar mechanical performance. On this sense, grinding with fine diamond bur before sintering (Fine group) was the best mimic protocol in comparison to the CAD/CAM milling.