Biologically Oriented Preparation Technique Through a Digital Workflow, a Case Report Part 1.

INTRODUCTION: In every prosthetic treatment, the final purpose of the restoration is to restore function and esthetics for the patient, respecting biology and anatomical parameters. Regarding full coverage restorations, there are some factors to take into consideration: like the finish line (chamfer, shoulder, featheredge, etc.), the management of the provisional restoration and tissue healing, the material for the final restoration, and the impression technique. All these aspects will determine the treatment process and its possible results. In recent years, vertical preparation and more specifically biologically oriented preparation technique has generated great interest since its introduction in prosthodontics, changing the periodontal tissues, and providing long-term stability. MATERIALS AND METHODS: With this technique, the objective is to change the position of the gingival margin, moving it more apically or coronally, depending on the modifications of the provisional. The relining of the provisional is a fundamental step of this technique: the intrasulcular part of the provisional is modified giving a new emergence profile and providing an augmentation of the tissue in the healing process. DISCUSSION: In vertical preparation, there is no predetermined margin. The dental technician should position the finish line more apically or coronally, depending on the depth of the sulcus and on the esthetic needs. Ceramic restorations should not invade the epithelial attachment, otherwise it may cause biological and mechanical problems, repetition of the impression, and of the crown restoration, which lead to increased clinical and laboratory time usage as well as expenses. One challenge is communicating the shape and contour of the temporary restoration to the dental lab to ensure accurate information for the final restoration. CONCLUSION: Finally, the objective of this article is to describe a technique for transferring all necessary information of the provisional and obtaining a predictable result for the final restoration by using an intraoral scanner system and the fabrication of two 3D printed prototypes. One for the final volume of the crowns and the other for the finish line position. CLINICAL SIGNIFICANCE: The fabrication of 3D printed prototypes allows for a more predictable final restoration, reducing possible communication errors between clinician and technician when restoring with biologically oriented preparation technique. In any esthetic treatment where the restoration does not have a predetermined margin, it is possible with this additional clinical step to provide a more esthetic outcome.

Deep margin elevation-Present status and future directions.

OBJECTIVE: Deep margin elevation (DME) is a treatment approach to relocate the cervical margin of teeth with subgingival defects to a supragingival position with a direct restoration to facilitate rubber dam isolation, impression taking, and bonding of indirect restorations. This article provides an overview of the current scientific evidence on DME and future directions for research. OVERVIEW: The review included 38 studies on DME, most conducted in vitro. These studies indicate that DME has no detrimental effect on the fracture resistance of restored teeth. Evidence on the impact of DME on marginal quality is conflicting, but most in vitro studies observed no negative effect. Clinical studies, most comprising small patient cohorts, demonstrated favorable restorative outcomes and suggest that DME restorations made with scrupulous care are compatible with periodontal health. Bleeding on probing may occur more frequently at sites with DME, though evidence on this is not unequivocal. CONCLUSIONS: Current evidence, based largely on laboratory studies and limited clinical data, supports DME as a viable approach to restore teeth with localized subgingival defects. However, further clinical studies with long-term follow-ups are required to provide corroborative evidence. CLINICAL SIGNIFICANCE: Current evidence suggests that DME is a viable approach to restore teeth with localized subgingival defects as a possible alternative to surgical crown lengthening. Proper working field isolation, meticulous care in the bonding and buildup procedure, and biofilm removal through patient-performed oral hygiene and professional maintenance care are crucial. As scant clinical trial-based evidence is available today, further research is needed to evaluate the long-term performance of DME restorations and their impact on periodontal health.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study.

OBJECTIVES: To assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays. MATERIALS AND METHODS: Permanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05). RESULTS: Simulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052). CONCLUSIONS: Artificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays. CLINICAL RELEVANCE: This laboratory study suggests that-in select cases-intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.

A digitally designed and 3D printed individual tooth tray for taking subgingival impression of complete crown preparation.

A digital technique for designing and fabricating an individual tooth tray used for taking subgingival impression of complete crown preparation was described. The digital model of required dentition region was obtained before performing crown preparation. An individual tooth tray with retention attachments was designed and printed with plastic material. After conducting crown preparation, the individual tooth tray loaded with the final impression material was placed onto the abutment to deliver the impression material subgingivally. A final overall impression was made with full arch stock tray to pick up the individual tooth tray with the accurate impression of abutment.

Periodontal response to two different subgingival restorative margin designs: a 12-month randomized clinical trial.

OBJECTIVES: Subgingival margin placement is sometimes required due to different reasons and is often associated with adverse periodontal reactions. The purpose of this study was to determine if a single restoration with subgingival margin on a tooth, in the maxillary anterior zone, would affect its periodontal soft tissue parameters, and whether or not a deep chamfer preparation has a different influence in the periodontium when compared to a feather edge preparation. MATERIAL AND METHODS: Plaque and gingival indexes, periodontal probing depth, bleeding on probing, and patient's biotype were registered. One hundred six teeth were prepared with a deep chamfer, while 94 were prepared with a feather edge finishing line. Twelve months after the restoration delivery, the same parameters were evaluated. Repeated measure one-way analysis of variance (ANOVA) (α = 0.05) was used. RESULTS: A statistically significant difference between the baseline and the 12-month follow-up is present in regard to plaque index, gingival index, and periodontal probing depth, but no statistically significant difference between chamfer and feather edge finishing lines. There is a statistically significant difference between the baseline and the 12-month follow-up in regard to bleeding on probing. Feather edge preparation presents significantly more bleeding on probing and less gingival recession than the chamfer. CONCLUSIONS: Subgingival margins do influence the periodontal soft tissue response. Statistically significant difference exists between feather edge and chamfer finishing lines in regard to bleeding on probing and gingival recession. CLINICAL RELEVANCE: Subgingival margins should be carefully selected, especially when feather edge finishing line is utilized.