Evaluation with a Coordinate-Measuring Machine of Dimensional Accuracy of the Abutment Duplication Technique in Cement- Retained Implant Restoration.

PURPOSE: To evaluate the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation. MATERIALS AND METHODS: A titanium, shoulderless abutment was chosen for a single-implant cemented rehabilitation. The master cast was made using a plastic-based die system, and the implant portion was separated. The implant section was consecutively duplicated eight times using a manual technique with polyvinyl siloxane and unfilled polyurethane resin as impression and die materials. The duplicates were analyzed with a coordinate-measuring machine (SmartScope Flash 200, Optical Gaging Products): one- and three- dimensional discrepancies were determined for each duplicate on 20 analysis points (A to T) located on the abutment surface. Changes in the abutment radius were also calculated to estimate the effects on cement thicknesses. RESULTS: One-dimensional discrepancies were -0.5 Å} 61.2 µm, -6.6 Å} 39.7 µm, and -19.4 Å} 47.8 µm on the X, Y, and Z axes, respectively; three-dimensional variation was -66.4 Å} 60.1 µm. Friedman test showed no significant difference between duplicates' one-dimensional variations on X (P = .059), Y (P = .156), or Z (P = .223) axes; a significant difference was found regarding three-dimensional changes (P < .001). Dunn test showed higher discrepancies on the X axis and on the abutment head. Mean variation of the abutment radius was -12.09 µm. CONCLUSIONS: The abutment duplication technique was shown to be an accurate and repeatable procedure for single cementable restorations.

Analysis of ultra-short implants with different angulations: a retrospective case-control study with 2 to 9 years of follow-up.

OBJECTIVES: Does the angulation of ultrashort implants influence the stability of the peri-implant bone? The present study aimed to evaluate the effectiveness of non-axial ultrashort implants after 2 to 9 years of follow-up in resorbed alveolar ridges. MATERIALS AND METHODS: All partially edentulous patients with ultrashort implants (< 6 mm) used in the posterior region of an atrophic mandible or maxilla, to support partial dentures in conjunction with standard implants, were included in this study. Peri-implant bone loss, success and survival rates, crestal bone levels, crown-to-implant ratio and implant angulation were measured for each implant. Implants were divided into two groups: straight implants with angulation < 17° (control group) and tilted implants with angulation > 17° (test group). Statistical analysis was used to find any significant differences between the two study groups and to investigate significant linear correlations among all the variables (p = 0.05). RESULTS: A total of 42 ultrashort implants with a mean of 4 years of follow-up were included: 20 ultrashort axially loaded implants and 22 tilted implants. Mean crestal bone levels from baseline loading to maximum follow-up did not reveal statistical differences in regard to PBL; mean success and survival rates were 100% in all groups. CONCLUSIONS: PBL, success and survival rates of axial ultrashort implants and tilted ultrashort implants are comparable to those of conventional implants. CLINICAL RELEVANCE: This retrospective study revealed that ultrashort implants, even when placed with an angulation > 17°, can safely be used to support partial fixed prostheses. Further prospective clinical studies with larger samples and prospective design are needed to confirm these findings.

Evaluation with a coordinate measuring machine of dimensional accuracy of the Abutment Duplication Technique in cement-retained implant restoration.

PURPOSE: To evaluate the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation. MATERIALS AND METHODS: A titanium shoulder-less abutment was chosen for a single-implant cemented rehabilitation. The master cast was made using a plastic-based die system, and the implant portion was separated. The implant section was consecutively duplicated eight times using a manual technique with polyvinyl siloxane and unfilled polyurethane resin as impression and die materials. The duplicates were analyzed with a coordinate-measuring machine (SmartScope Flash200, OGP): one- and three- dimensional discrepancies were determined for each duplicate on 20 analysis points (A-T) located on the abutment surface. Changes in the abutment radius were also calculated to estimate effects on cement thicknesses. RESULTS: One-dimensional discrepancies were -0.5 µm ± 61.2µm, ¬-6.6 ± 39.7 µm, and -19.4 ± 47.8 µm on X, Y, and Z axes, respectively; three-dimensional variation was -66.4 ± 60.1 µm. The Friedman test showed no significant difference between duplicates' one-dimensional variations on X (p = 0.059), Y (p = 0.156), or Z (p = 0.223) axes; a significant difference was found regarding three-dimensional changes (p < 0.001). The Dunn test showed higher discrepancies on the X axis and on the abutment head. Mean variation of the abutment radius was -12.09 µm. CONCLUSION: The abutment duplication technique was shown to be an accurate and repeatable procedure for single cementable restorations.