In vitro assessment of cutting efficiency and durability of zirconia removal diamond rotary instruments

Statement of problem

Recently, zirconia removal diamond rotary instruments have become commercially available for efficient cutting of zirconia. However, research of cutting efficiency and the cutting characteristics of zirconia removal diamond rotary instruments is limited.

Could different direct restoration techniques affect interfacial gap and fracture resistance of endodontically treated anterior teeth?

Clinical Oral Investigations - To evaluate different direct restoration techniques on various cavity designs in anterior endodontically treated teeth (ETT). Ninety upper central incisors (n = 90)...     

In vitro evaluation of the polishing effect and optical properties of monolithic zirconia

Statement of problem

The relationship between surface roughness and the optical characteristics of zirconia prostheses may be affected by the type of shaded block.

Fracture resistance of endodontically treated teeth restored with indirect composite inlay and onlay restorations – An in vitro study

Objective

The purpose of this in vitro study was to evaluate and compare the fracture resistance and fracture mode of extensive indirect inlay and onlay composite resin restorations performed for endodontically treated premolars.

Materials and methods

A total of 55 extracted maxillary premolars were randomly divided into four groups. The first group (n = 15) remained untreated to serve as a positive control; the second group (n = 15) was endodontically treated with inlay cavities prepared and restored with indirect composite inlay restorations; the third group (n = 15) was also endodontically treated with onlay cavities prepared and restored with indirect composite onlay restorations; and the fourth group (n = 10) was endodontically treated with mesio-occlusodistal (MOD) cavities prepared and left unrestored to serve as negative controls. Dual cure indirect composite resin was used to fabricate the inlay and onlay restorations performed for the second and third groups, respectively. All teeth were subjected to compressive axial loading test using a metal ball (6 mm in diameter) in a universal testing machine (Instron 1195) with a cross-head speed of 0.5 mm/min until a fracture occurred. Statistical analysis of fracture resistance and fracture mode were performed with analysis of variance (ANOVA) (α = 0.05) and Kruskal–Wallis (α = 0.05) tests, respectively.

Results

For the four treatment groups, the mean fracture resistance values were 1326.9 N, 1500.1 N, 1006.1 N, and 702.7 N, respectively. Statistical analyses showed no significant differences between the mean fracture resistance of the intact tooth group and the inlay restoration group (p > 0.05), while significant differences were observed between the mean fracture resistance of all the other groups (p < 0.05). The Kruskal–Wallis test showed statistically significant differences between the fracture modes of the four groups.

Conclusion

Within the limitations of this study, endodontically treated teeth were successfully restored with indirect composite inlay and onlay restorations. However, the fractures that accompanied the inlay restorations were more severe and were unable to be restored.     

In Vivo and In Vitro Comparison of Internal and Marginal Fit of Digital and Conventional Impressions for Full-Coverage Fixed Restorations: A Systematic Review and Meta-analysis

PurposeThis study aims to evaluate digital and conventional impressions for full-coverage restorations in terms of marginal and internal discrepancies.Study selectionThe analysis included in vivo and in vitro studies reporting the marginal or internal gap of full-coverage restorations that provide both the conventional and digital impression. The PubMed, Cochrane Trials, and Scopus databases were searched. The quality of clinical trials was rated using Cochrane Collaboration's tool, and the quality of the evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation tool. Heterogeneity among the studies was evaluated, and a meta-analysis with subgroup analysis was conducted whenever it was possible.ResultsThirty-three articles (8 prospective clinical trials and 26 in vitro studies) were selected to extract data after applying the predefined selection criteria. The standard mean difference (SMD) of the meta-analysis for marginal adaptation was ?0.76 (95% confidence interval: ?1.23 to ?0.29) and ?0.59 (95% confidence interval: ?0.93 to ?0.24) for in vitro and in vivo studies, respectively, indicating digital impressions provided significantly less marginal gap than conventional impressions in in vitro studies (P = .002). The impression technique did not significantly influence the internal adaptation.ConclusionsDifferences in marginal adaptation between the digital and conventional groups are not significant for in vivo studies, but for in vitro studies, the digital impression resulted in better marginal adaptation. Based on the Grading of Recommendations, Assessment, Development, and Evaluation approach for marginal adaptation, clinical studies were classified as high confidence and in vitro studies were graded moderate because of the inconsistency. Furthermore, high-quality studies are needed to confirm our results (the International Prospective Register of Systematic Reviews; CRD42017077925).     

In Vivo and In Vitro Effectiveness of Rotary Nickel-Titanium vs Manual Stainless Steel Instruments for Root Canal Therapy: Systematic Review and Meta-analysis

Introduction

This systematic review evaluated the effectiveness of nickel-titanium (NiTi) rotary files compared to stainless-steel (SST) hand files.

In vitro comparison of the load-bearing capacity of ceramic and metal-ceramic resin-bonded fixed dental prostheses in the posterior region

Statement of problem

The clinical use of ceramic resin-bonded fixed dental prostheses (RBFDPs) in the posterior region is desirable for esthetic and biological reasons but has been associated with many technical problems, including fractures or chipping of the veneer. Although these problems may be overcome by using monolithic zirconia, information is lacking about the load-bearing capacity of resin-bonded monolithic zirconia restorations for replacing a molar.

In vitro fit of CAD-CAM complete arch screw-retained titanium and zirconia implant prostheses fabricated on 4 implants

Statement of problem

Computer-aided designed and computer-aided manufactured (CAD-CAM) titanium and zirconia implant-supported fixed implant prostheses on 4 implants have become popular. The precision and accuracy of their interface fit has not been widely researched.

Torque resistance of impression copings after direct implant impression: An in vitro evaluation of impression materials with and without adhesive

Statement of problem

No data are available on the ability of an impression coping to resist the manual placement of an abutment replica (implant analog) during prosthodontic laboratory procedures after a direct (pick-up) impression.

The selection of anterior teeth appropriate for the age and sex of the individual. How variable are dental staff in their choice?

As part of the development of a guide to aid the undergraduate in the selection of artificial teeth, the aim of this study was to investigate the variability in choice of dental staff to select teeth appropriate to the age and sex of the individual with the aid of a series of three-dimensional guides. Four three-dimensional guides were produced for use in the study. Fifty dentists were asked to complete a questionnaire designed to assess the variability in selection of anterior teeth appropriate for the age and sex of an individual. From this study it can be concluded that there was little consistency in the selection of the shade, mould and arrangement of anterior teeth appropriate for the age and sex of the individual by qualified dental staff. The development and implementation of an aesthetic proforma to guide dental staff, dental undergraduates and patients through the process of choosing tooth mould, shade and arrangement based on age and sex may be helpful.     

Biocompatibility of primers and an adhesive used for implant-retained maxillofacial prostheses: An in vitro analysis

Statement of problem

Implant-retained maxillofacial prostheses should be biocompatible, regardless of the primers and adhesives used to bond the acrylic resin and facial silicone. The authors are unaware of any study evaluating the influence of these primers and adhesives on the biocompatibility of maxillofacial prostheses.

Volumetric shrinkage and film thickness of cementation materials for veneers: An in vitro 3D microcomputed tomography analysis

Statement of problem

Few studies have investigated the volumetric polymerization shrinkage and film thickness of the different cementation techniques used to cement veneers.

In Vitro Evaluation of a Novel Root Canal Endoscope for Visualizing the Apex of Curved Root Canal Models and an Extracted Tooth

Introduction

In straight root canals, intraradicular structures around the root canal orifice and apical foramen can be visualized with a dental operating microscope and commercially available root canal endoscopes. However, the root apex area, including the apical foramen, in a curved root canal cannot be visualized using these devices. In the present study, the potential of a newly developed root canal endoscope implementing an image fiber was examined in 3 types of root canal models and extracted teeth.

A new multilayered membrane for tissue engineering of oral hard- and soft tissue by means of melt electrospinning writing and film casting – An in vitro study

Membranes that form a mechanical barrier not only for cells but also for the bacterial flora of the oral cavity may be helpful in infection-free wound healing for guided tissue regeneration (GTR) applications in the field of oral- and maxillofacial surgery. Controlled wound healing without interference from bacterial contamination appears to be achievable in combination with surface scaffolds for bone- and soft tissue regeneration. As this has not yet been realized, we developed multilayered membranes in this study consisting of specific surface scaffolds for bone- and mucosal regeneration as well as bacteria-tight core membranes. These membranes were evaluated in terms of cell growth of osteoblast- (MG63), keratinocyte- (HaCaT), and fibroblast (L929) cell lines. Scaffolds were fabricated via melt electrospinning writing (MEW), while the core membrane was produced via film casting. All constructs were made of medical-grade poly(ε-caprolactone) (PCL). The bacteria-tightness was tested via a bacterial transmigration-assay. PCL scaffolds and core membranes alone demonstrated good cytocompatibility for all cell lines, which was even enhanced by fusing both components together. The core membrane displayed complete bacteria-tightness over two weeks. These bacteria-tight, individually-designed membranes from medical-grade PCL represent a high-potential, clinically oriented method of GTR in the field of oral- and maxillofacial surgery.