Objective This study compared digital and conventional impression techniques regarding impression time, frequency of adjustments, and adaptation of cobalt‐chromium (Co‐Cr) copings with supragingival and subgingival finish lines. Materials and Methods Thirty premolars prepared for single‐unit metal‐ceramic restorations with supragingival and subgingival finish lines (n = 15). Conventional impression and digital scan of prepared teeth were made. Using computer aided design/computer aided manufacturing (CAD/CAM) system the copings were produced by a milling machine from Co‐Cr blocks and internal and marginal discrepancies were measured using silicone replica technique. Data were analyzed using repeated measures ANOVA and Mann‐Whitney test (alpha = .05). Results The impression technique had a significant effect on the magnitude of gap (P < .001). The internal and marginal gaps in the digital technique (49.43 μ and 60.07 μ, respectively) were significantly lower than the values in the conventional method (91.88 μ and 96.96 μ, respectively—P < .001). Finish line positions had no significant effect on the fit and marginal gap of copings (P = .54 and .243, respectively). The mean impression time (19′:27″ in conventional technique and 10′:31″ in digital technique) was significantly shorter (P < .001) and the mean frequency of adjustments (2.2 times for conventional and 1.3 times for digital technique) was significantly lower in the digital technique (P < .001). The gingival biotype (thick or thin) had no significant effect on marginal and internal fit (P = .052 and .319, respectively). Conclusion The digital technique was superior in terms of fit, impression time, and frequency of adjustments. Finish line positions had no significant effect on the fit of copings. Clinical Significance Using intraoral scanner promotes the fits of restorations in supragingival and subgingival finish lines.

In the metal-free copings tested, zirconia showed the best adaptation. The retention of copings was not influenced by internal fit or material type.

No abstract

Aim:The aim of this review is to summarize and discuss the available information concerning the connection between the tooth and implant in a fixed partial denture. Background:Although implant-supported prosthesis (ISP) has substantial biological and biomechanical advantages, due to the extensive use of implant in partially edentulous patients, encounter to cases of obligatory connection between the tooth and implant is not rare. However, because of their differences, especially in support mechanism, long-term prognosis of this treatment method is a special debate in dental literature. Materials and methods:The literature published over the past 25 years was searched through PubMed, Medline, Google and indexed journals (search terms: tooth implant connection, tooth implant-supported fixed partial denture, tooth implant splinting, implant and tooth). The most valuable and relevant articles were selected and analyzed. Results and discussion:The existing studies reveal that there are certain conditions in which this method is applicable. The main advantage of the method based on literature reviewed is reducing the need to the removable prosthesis in patients that otherwise require it. The disadvantages of this connection, mainly due to different movement range of components under loading, reportedly will be minimized if some guidelines are followed.Clinical significance: According to available studies, this literature review supports tooth-implant connection technique where indicated, with complete attention to prudent guidelines. Further researches preferably concentrating on new methods and also long-term longitudinal studies are certainly needed before this approach can be widely used.

The CAD/CAM technique for wax milling resulted in more retentive copings with better marginal and internal adaptations compared with milling the metal blocks.

Purpose. This study aimed to compare marginal and internal adaptation in endocrowns made from translucent zirconia and zirconium lithium silicate using CAD-CAM technology. Materials and Methods. Twenty-eight freshly extracted upper molars were mounted in acrylic resin and underwent root canal therapy and endocrown preparation up to 2 mm above the cementoenamel junction. Endocrowns were CAD-CAM milled from zirconium lithium silicate (ZLS) and translucent zirconia (Zr). Internal and marginal adaptation was assessed by the replica technique before cementation. Marginal adaptation was evaluated by a stereomicroscope (×32) before and after cementation and also after thermomechanical aging. Results. The ZLS group showed significantly higher internal adaptation compared to the Zr group ( P  = 0.028), while the marginal adaptation differences, at different times with different methods, were not statistically significant ( P  > 0.05). Axiomarginal angle had the highest and axiopulpal angle showed the lowest adaptation in both groups. The cementation process and thermomechanical aging increased the marginal gap in both groups significantly ( P  < 0.001). The marginal gap assessed by the replica technique before cementation was 7.11 µm higher than direct view under a stereomicroscope with intraclass correlation coefficient of 0.797. Conclusion. Zirconia seems to be an acceptable material for endocrown with comparable internal and marginal adaptation to ZLS. Cementation and thermomechanical aging had significantly negative effects on marginal gap. The marginal gap assessed by the replica technique was higher than direct view under the stereomicroscope technique.

Objectives: Bone remodeling after tooth extraction results in decreased ridge volume and complicates implant placement. Platelet-rich fibrin (PRF) is a rich source of autogenous cytokines and growth factors; it has been proven to effectively improve soft tissue healing and hard tissue regeneration. This study sought to compare the clinical application of freeze-dried bone allografts (FDBA) and PRF for alveolar ridge preservation after tooth extraction. Materials and Methods: This clinical trial was conducted on 32 patients presenting for the extraction of hopeless non-molar teeth. The teeth were extracted with minimal trauma, and the samples were randomly divided into two groups (n=16). Tooth sockets were filled with either FDBA or PRF (prepared using 10cc of the patient’s blood). Bone regeneration was assessed by evaluating changes in horizontal and vertical bone dimensions after 12 weeks (the time of implant placement) using an acrylic stent fabricated before tooth extraction and a periodontal probe. The results were compared by repeated-measures analysis of variance (ANOVA; P<0.05). Results: Ridge width showed a significant reduction compared to the baseline in both groups (P=0.001); ridge height changes were not significant (P>0.05). The evaluated groups did not show any significant difference in height/width changes (P>0.05). Conclusion: The results showed an acceptable efficacy for PRF without graft materials in alveolar ridge preservation. This material is cost-effective and could be easily prepared. PRF application in extraction sockets yielded similar results to FDBA.

Background This study aimed to compare retention and fracture load in endocrowns made from translucent zirconia and zirconium lithium silicate. Methods Fifty-six intact human maxillary molars after being mounted in acrylic resin, were scanned to acquire biogeneric copies. Specimens underwent standard endodontic treatment and were prepared for endocrown up to 2 mm above the cementoenamel junction. The specimens were randomly divided into two groups of 28, and endocrowns were designed using biogeneric copies and milled from high-translucent zirconia disks (Zr) and zirconium lithium silicate blocks (ZLS). After cementation with dual-cure resin cement, all the specimens underwent thermomechanical aging, and pull-out retention test and compressive test were conducted (14 specimens were used for each test in each group, n = 14), and failure modes in both tests were evaluated. Results Independent samples t-test showed significant difference between the retention of Zr (271.5 N ± 114.31) and ZLS (654.67 N ± 223.17) groups (p value = 0.012). Compressive test results were also significantly different between Zr (7395.07 N ± 1947.42) and ZLS (1618.3 N ± 585) (p = 0.002). Failure mode of retention test was primarily adhesive failure at the cement-restoration interface in Zr group and cement-tooth interface in ZLS group. Failure modes of fracture test for Zr group were 7 non-restorable fractures and one restorable fracture while 6 specimens resisted compressive loads up to 8500 N without fracture. ZLS group showed 7 restorable and 7 non-restorable failures. Conclusions Zr endocrowns showed significantly lower retention and higher fracture strength. Both materials seem to be suitable for fabrication of endocrown in clinical setup.