Application of 3D digital smile design based on virtual articulation analysis in esthetic dentistry: A technique

Influence of soft tissue thickness, blade type, and guide design, on computer-assisted esthetic crown lengthening

BACKGROUND

The aim of this study was to evaluate the effect of surgical guide design and type of blade, in relation to soft tissue thickness, on the accuracy of computer-assisted crown lengthening.

METHODS

A set of fully dentate anatomic maxilla models was implemented, using 2 types of soft-tissue masks with a mean thickness of 1.5  and 3.5 mm, respectively, to simulate a clinical scenario of altered passive eruption. In total, 5 different gingivectomy techniques were assessed, implementing 3 different types of guidance and 2 different blades. The osteotomy was performed using 2 surgical guide designs. After each operation, the models were scanned and superimposed with the initial virtual design, to evaluate the accuracy of each evaluated approach through a set of linear measurements.

RESULTS

For the gingivectomy as well as for the osteotomy, the mean discrepancy was increased in the presence of increased soft tissue thickness (p < 0.05). The integration of supporting planes led to a decrease in the discrepancy compared to the conventional double guide design for both of the investigated soft-tissue thicknesses (p < 0.05). For the models with the normal soft tissue thickness, a lower mean discrepancy was presented, when a mini blade was used instead of a conventional surgical blade, irrespective of the guide design (p < 0.05).

CONCLUSION

Computer-assisted crown lengthening can be considered a feasible treatment option. Soft tissue thickness has to be taken into consideration during the design of the surgical template, in order additional support to be provided when it is needed. Surgical templates with integrated supporting planes can increase the accuracy of computer-assisted crown lengthening.

PLAIN LANGUAGE SUMMARY

Gingival architecture plays a crucial role in achieving smile harmony. For patients seeking an esthetic smile, periodontal plastic surgery can be a valuable option, as it can improve the harmony between the teeth and the gingiva. Excessive gingiva display can be managed using various treatment approaches, depending on the etiology. When periodontal surgery is a part of the treatment plan, the procedure can be digitally planned using a 3D diagnostic design and seamlessly transferred to the surgical field through a 3D printed surgical template. The present research aimed to evaluate the influence of surgical guide design, gingival thickness, and surgical blade type on the accuracy of the periodontal surgery. Two different designs of surgical templates, providing a different degree of guidance, as well as 2 types of surgical blades were used to simulate the surgical procedure. To evaluate the aforementioned parameters, models with 2 different gingival mask thickness were used. Based to the results of the present study, gingival thickness, surgical template design, and blade type can significantly affect the accuracy of the surgery procedure.

Digital Protocol to Record Occlusal Analysis in Prosthodontics: A Pilot Study

Background: Digital technologies enable the accurate replication of occlusion, which is pivotal for stability in maximum intercuspation and dynamic occlusion. CAD softwares generates standardized occlusal morphologies requiring significant adjustments. The consideration of individual mandibular movements during restoration leads to better functional integration. This pilot study evaluates the efficacy of a novel, fully digital protocol for occlusal analysis recording in prosthodontics. Methods: Patients needing single or multiple metal-free restorations were included. Teeth underwent horizontal finish line preparation, while restorations on implants were either directly screwed or used multi-unit abutments. A digital impression (Trios 3 Intraoral Scanner) captured the mouth's elements. Dynamic occlusion was recorded via Patient Specific Motion (PSM). After the placement and functionalization of temporary restorations, subsequent scans included various elements, and CAD software (Dental system) was used for the restoration design. Restorations were milled in monolithic zirconia, pressed from CAD/CAM-milled wax, and sintered. Results: An evaluation of 52 restorations in 37 patients indicated high accuracy in restorations manufactured via the fully digital workflow. Monolithic zirconia was predominantly used. Subtractive (17.3%) and additive (7.7%) occlusal adjustments were mainly chairside. Conclusion: This study underscores the efficacy of meticulous verification measures and a centric contact system in reducing the need for clinical occlusal refinements in prosthetic restorations.