A Novel Technique for Immediate Loading Single Root Form Implants With an Interim CAD/CAM Milled Screw-Retained Crown

Accuracy evaluation of 3D printed interim prosthesis fabrication using a CBCT scanning based digital model

OBJECTIVES

This study aimed to evaluate the marginal and internal gaps in 3D-printed interim crowns made from digital models of cone-beam computed tomography (CBCT) conversion data.

MATERIALS AND METHODS

Sixteen polyvinylsiloxane impressions were taken from patients for single crown restorations and were scanned using CBCT. The scanning data were converted to positive Standard Triangulation Language (STL) files using custom-developed software. The fabricated stone models were scanned with an intraoral optical scanner (IOS) to compare the surface accuracy with the STL data obtained by CBCT. The converted STL files were utilized to fabricate interim crowns with a photopolymer using a digital light-processing 3D printer. The replica method was used to analyze the accuracy. The marginal and internal gaps in the replica specimen of each interim crown were measured with a digital microscope. The Friedman test and Mann-Whitney U test (Wilcoxon-signed rank test) were conducted to compare the measurements of the marginal and internal gaps with a 95% level of confidence.

RESULTS

The root-mean-square values of the CBCT and IOS ranged from 41.00 to 126.60 μm, and the mean was 60.12 μm. The mean values of the marginal, internal, and total gaps were 132.96 (±139.23) μm, 137.86 (±103.09) μm, and 135.68 (±120.30) μm, respectively. There were no statistically significant differences in the marginal or internal gaps between the mesiodistal and buccolingual surfaces, but the marginal area (132.96 μm) and occlusal area (255.88 μm) had significant mean differences.

CONCLUSION

The marginal gap of the fabricated interim crowns based on CBCT STL data was within the acceptable range of clinical success. Through ongoing developments of high-resolution CBCT and the digital model conversion technique, CBCT might be an alternative method to acquire digital models for interim crown fabrication.

An alternative method for immediate implant-supported restoration of anterior teeth assisted by fully guided templates: A clinical study

STATEMENT OF PROBLEM

Immediate implant-supported restorations have become a common treatment strategy in the esthetic zone; however, improvements are necessary in the techniques used to fabricate interim prostheses.

PURPOSE

This clinical study evaluated an alternative method for the immediate restoration of anterior teeth by using a fully guided template.

MATERIAL AND METHODS

Twenty-five participants were enrolled, and 30 implants were inserted by using fully guided templates. Eleven participants and 14 implant sites were treated with immediate implant placement. Fourteen participants and 16 implant sites were treated with delayed implant placement. The same method was used for immediate restoration in all the participants. A postoperative cone beam computed tomography (CBCT) scan was compared with the preoperative planning to measure the deviation between the placed and the planned implants. The independent t test was used for the comparison of immediate and delayed implant placement (α=.05). Any complications occurring in the following 3 months were also recorded.

RESULTS

None of the interim prostheses needed significant adjustments and were successfully installed on implants after the surgery. The overall mean deviations in 3D coronal, buccolingual coronal, mesiodistal coronal, 3D apical, buccolingual apical, mesiodistal apical, depth, and angle were 0.6 ±0.3 mm, 0.4 ±0.2 mm, 0.2 ±0.1 mm, 1.0 ±0.4 mm, 0.7 ±0.4 mm, 0.3 ±0.2 mm, 0.4 ±0.3 mm, and 1.9 ±1.1 degrees, respectively. The linear and angular deviations exhibited no significant differences (P>.05) between immediate and delayed implant placement. No complications developed in the follow-up period.

CONCLUSIONS

In the anterior esthetic zone, this alternative method appears to be suitable for immediate restoration. The accuracy of fully guided surgery was clinically acceptable for the prefabricated interim prostheses and helped reduce postoperative chairside time.

Use of Implant-Supported Custom Milled Impression Copings to Capture Soft-Tissue Contours and Incisal Guidance

A technique is presented where a custom milled impression coping is used to replicate the clinically established anterior incisal guidance to the definitive prosthesis when multiple implants are restored in the esthetic zone. A conventional impression is initially made, then the stone cast is scanned, and a digitally designed custom screw-retained, implant-supported interim prosthesis is milled from a polymethylmethacrylate (PMMA) billet. This is aimed to digitally design the pontic areas, contour the gingival soft tissue, and establish an anterior incisal guidance. A custom milled impression coping (CMIC) is then fabricated. The CMIC has contours similar to the contours of the interim prosthesis and is fabricated from a PMMA billet. Titanium inserts are placed in the interim prosthesis and the CMIC. The CMIC is inserted intraorally and used for the final impression by using a custom tray and by following the open tray impression protocol. With the proposed technique, the exact contours of the digitally designed and clinically verified interim prosthesis are used to fabricate the definitive restoration.

Use of Patient's Own Natural Teeth as Part of the Interim Prosthesis on Immediately Placed Single Implants in a Staged Surgical Approach: A Clinical Report

A technique is described where the tooth's natural crown is used as part of the interim implant supported prosthesis in clinical situations where a tooth with poor prognosis is extracted and an implant is placed immediately after tooth extraction. A preliminary impression is made before tooth extraction, and the exact tooth positioning is assessed in the laboratory as part of the treatment plan. An acrylic resin repositioning jig is fabricated that will guide the clinician in seating and orienting the crown intraorally after implant placement is completed. After the natural tooth is extracted and an implant is immediately placed via guided approach, the extracted natural crown is hollowed and placed on top of an interim abutment. The natural crown is positioned intraorally by using the acrylic resin repositioning jig. The crown is then internally relined and placed as part of the interim implant supported prosthesis. After osseointegration has been confirmed, a definitive prosthesis is placed.