Is the digital workflow more efficient for manufacturing partial-coverage restorations? A systematic review

STATEMENT OF PROBLEM

A consensus on whether a fully digital workflow can replace conventional methods of manufacturing partial-coverage restorations is lacking.

PURPOSE

The purpose of this systematic review was to evaluate the accuracy, fit, and clinical outcomes of inlay, onlay, overlay, and endocrown restorations obtained with both digital and conventional workflows.

MATERIAL AND METHODS

This study complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered in the International Prospective Register of Systematic Reviews database (CRD42021258696). Studies evaluating the accuracy, fit, and clinical outcomes of inlay, onlay, overlay, and endocrown restorations obtained with digital and conventional workflows were included from 5 databases searched in November 2022. The Checklist for Reporting Randomized Clinical Studies (ROB 2) and the Checklist for Reporting In vitro Studies (CRIS guidelines) were used to assess the risk of bias.

RESULTS

Twenty-three studies were included in this review. Sixteen studies evaluated marginal and internal fit, 5 evaluated accuracy, 3 evaluated fracture resistance, and 1 evaluated long-term clinical performance. Although most studies reported acceptable clinical outcomes for both workflows, 11 studies showed better results with the conventional workflow, 10 with the digital workflow, and 2 reported that the outcomes of the workflows were similar.

CONCLUSIONS

Clinically acceptable values have been reported for the parameters evaluated in both digital and conventional workflows, and no consensus has been reached regarding the more efficient method.

Assessment Methods for Marginal and Internal Fit of Partial Crown Restorations: A Systematic Review

BACKGROUND

Different methods are used for the analysis of marginal and internal fit of partial crowns, but not all of them are applicable for in vivo studies. The aim of this review is to search the available methods, described in the current literature, to assess marginal and internal fit in partial crowns.

METHODS

an electronic search was performed on Pubmed and Web of Science databases to find studies published from 1 January 2017 up to 2 March 2023, following PRISMA guidelines and Cochrane handbook for systematic reviews. The search strategy applied was: "(marginal) AND (fit OR gap OR adaptation OR discrepancy) AND (inlay OR onlay OR partial crown)". In vitro studies which evaluated marginal and internal fit on CAD CAM or 3D printed partial crowns were included in this review. Quality of the studies was assessed by using Quality Assessment Tool For In Vitro Studies (QUIN tool).

RESULTS

22 studies were included. Among conventional methods, direct view with microscope, indirect view on resin replicas, and silicone replica technique (SRT) were used. Considering new digital methods, micro-CT, SRT 3D and triple scan technique (TST) were applied.

CONCLUSIONS

Among 2D methods, direct view technique is the most used marginal fit analysis. For a more comprehensive evaluation, a 3D digital analysis is suggested. SRT and indirect view are the only 2D methods available for in vivo analysis. A protocol for the application of TST for assessment in vivo is now available, but no studies are reported in literature yet.

Does overlay preparation design affect polymerization shrinkage stress distribution? A 3D FEA study

This study evaluated the polymerization shrinkage stress of three tooth preparation designs for indirect ceramic overlay by finite element analysis: isthmus preparation (IST); without isthmus preparation (wIST); and non-retentive preparation (nRET). The models were created based in prepared dental typodonts and were digitally impressed with an intraoral scanner. The interfaces in all models were considered perfectly bonded and all materials were considered homogeneous, linear, and isotropic. The polymerization shrinkage of the cement layer (100 µm) was simulated and evaluated by maximum principal stress criteria. The stress peaks followed this sequence: restoration = IST (13.4 MPa) > wIST (9.3 MPa) > nRET (9 MPa); cement layer = IST (16.9 MPa) > wIST (12.6 MPa) > nRET (10-7.5 MPa); and teeth = IST (10.7 MPa) > wIST (10.5 MPa) > (9 MPa). For the cement layer, the non-retentive preparation (nRET) had the lowest shrinkage stress from all the groups, obtaining a more homogeneous stress distribution on the cement surface. Regarding the abutment teeth, the IST generated a higher shrinkage stress area on the dental structure, concentrating higher stress magnitude at the axiopulpar and axiogingival angles. Non-retentive preparation seems to reduce polymerization shrinkage stress.

A clinical evaluation of resin nanoceramic CEREC Omnicam restorations associated with several factors

PURPOSE

The aim of this study was to assess the clinical performance of computer-aided design and computer-aided manufacturing resin nanoceramic posterior restorations fabricated by CEREC Omnicam system.

MATERIALS AND METHODS

Fifty-seven Lava Ultimate posterior restorations were placed in 44 patients by one operator. Restorations were cemented using a resin cement system (Duo-Link). The clinical performance of the restorations was evaluated with USPHS guidelines in a mean time of 45-month. Data were statistically analyzed using Kaplan-Meier and Log Rank (Mantel-Cox) tests (SPSS 22.0, α = 0.05).

RESULTS

Thirty-eight restorations in 26 patients were evaluated at recall examinations by two evaluators other than the clinician who had placed the restorations who were blinded to groups. The survival rates of Lava Ultimate were 86.8%. A total of 5 (13.2%) failures were found. After a mean time of 45-month survival rate of vital and non-vital teeth were 90 and 83.3% respectively. The failures were not significantly influenced by gender, tooth arch, restoration size, the treated region and vitality.

CONCLUSION

Chair-side posterior resin nanoceramic restorations were clinically successful restorations with a survival rate of 86.8% after a mean time of 45-month.

CLINICAL SIGNIFICANCE

Chair-side CAD/CAM resin nanoceramic restorations can be a successful choice for vital and non-vital teeth with acceptable survival rates.

DSDapp use for multidisciplinary esthetic planning

OBJECTIVES

Digital smile design (DSD) is useful in planning multidisciplinary esthetic treatments. However, DSD requires clinician training and skill to ensure its effective use. The Digital smile design application (DSDapp) was recently developed, to facilitate such planning. The objective of this study was to illustrate the use of the DSDapp for esthetic planning in a clinical case that included periodontal plastic surgery and ceramic laminate veneers.

CLINICAL CONSIDERATIONS

An intraoral digital scan was performed, and a photograph was obtained using an iPad (frontal facial full smile). The images were analyzed using the DSDapp. All reference lines were inserted, and dental shapes predetermined by the app were superimposed on the photographs. A digital diagnostic wax-up was performed considering the plan created in the DSDapp. After 3D printing the wax-up, a mock-up transferred the planning to the oral cavity. Following this, the patient was referred to a periodontist for the periodontal plastic surgery. After the healing period, the teeth were prepared for computer-aided design/computer-aided modeling lithium disilicate ceramic laminate veneers.

CONCLUSIONS

DSDapp use accelerated the initial planning steps. Smile planning can be performed during the clinical session with the patient's active participation. In addition, the DSDapp facilitated better communication within the multidisciplinary team.

CLINICAL SIGNIFICANCE

The DSDapp relies more on intuition than on skill and training to execute the treatment plan. The DSDapp provides immediate feedback to the patient, offering greater predictability and helps monitor the planning through all the clinical stages.