Insertion Torque and Resonance Frequency Analysis in Tapered and Parallel Dental Implants.

Primary implant stability (PIS) is known to vary with recipient bone mass and density, dental implant design and surgical technique. The objective of this preliminary study was to compare rotational and lateral PIS of same-coronal-diameter conical and parallel implants, using insertion torque recorded with a dental implant motor set and implant stability quotient obtained from resonance frequency analysis (performed with both Osstell and Penguin systems) as measures of rotational and lateral stability, respectively. Additionally, the relationship between PIS and alveolar ridge width (ARW) was explored in both implant types. Sixty dental implants (30 tapered and 30 parallel) were randomly placed with a split-mouth design in 17 patients. Bone density and ARW were estimated from cone beam computed tomography images taken with radiological-surgical templates. Density and width values were similar in the 2 groups (P > .05). Implant coronal diameters were 3.75 mm in all cases, while consistent with the manufacturer's recommendations, final drill bit diameters used were 3.25 and 3.4 mm for parallel and tapered implants, respectively. Insertion torque was higher (P < .05) with parallel implants, but between-group differences in implant stability quotient were not significant (P > .05). In tapered implants, insertion torque was inversely correlated with ARW (P < .001). Notably, significant differences were observed between resonance frequency analysis values from Osstell and Penguin systems (P < .001). In conclusion, future studies should explore how PIS may be influenced by final drill bit size regardless of implant design and potential limits on the effectiveness of tapered implants to achieve good stability in thick low-density bone.

Implant-prosthetic Rehabilitation with and without Platform Switching: A Retrospective Clinical Cohort Study.

AIM: The study aimed to retrospectively compare peri-implant bone loss, prosthetic complications, and patient-reported outcome measures (PROMs) after implant-prosthetic treatment on abutments with platform switch or platform match. MATERIALS AND METHODS: Records of patients, who received implant-prosthetic treatment on abutments with/without platform switch in a single dental clinic between November 2015 and November 2018, were retrospectively analyzed. Analysis was restricted to the following patient selection criteria: no need for any bone grafting procedures before/during implant placement, and no serious systemic disease. Implants were conventionally loaded with screwed prosthetic restorations after a healing period of 3 months. Crestal bone loss was measured by digital radiography at implant placement and after at least 2 years under functional implant loading conditions. Patient satisfaction was recorded with the visual analogue scale (VAS) at the time of the follow-up examination. RESULTS: Clinical records of 59 patients were available for analysis. Patients of the study cohort received in total 128 implants with different lengths and diameters according to the manufacturer's specifications. Prosthetic restorations were fixed either on abutments with platform switch (BEGO PS-UNI: n = 74; 57.8%) or platform match (BEGO SUB-TEC Universal: n = 54; 42.2%). No implant was lost and no failure of prosthetic restoration was recorded during follow-up, except for prosthetic screw loosening in 32 implants (25.0%). Abutment type and location (maxilla vs mandible) had a significant impact on peri-implant bone loss (OR = 3.4; 2.8). A significant reduced rate of bone loss was observed at implant sites, provided with abutments according to the platform switch concept (35.1 vs 64.8%). No significant correlation was recorded between less bone loss and a higher patient satisfaction, while loosening of the prosthetic screw was significantly associated with lower satisfaction scores. CONCLUSION: BEGO PS-UNI abutments with a platform switch design revealed significant less crestal bone loss after a mean observation period of 20.8 months. CLINICAL SIGNIFICANCE: Abutments with a platform switch design may lead to less peri-implant bone loss. In order to maintain a higher patient satisfaction, clinicians should focus on the quality of the implant-prosthetic connection in screwed restorations.

Alveolar Bone Density and Width Affect Primary Implant Stability.

Primary implant stability (PIS) depends on surgical technique, implant design, and recipient bone characteristics, among other factors. Bone density (BD) can be determined in Hounsfield units (HUs) using cone beam computerized tomography (CBCT). Reliable prediction of PIS could guide treatment decisions. We assessed whether PIS was associated with recipient bone characteristics, namely, BD and alveolar ridge width (ARW), measured preoperatively by CBCT. We studied a convenience sample of 160 implants placed in 48 patients in 2016 and 2017. All underwent CBCT with a radiologic/surgical guide yielding values for ARW and BD. PIS measures used were the implant stability quotient (ISQ) from resonance frequency analysis and insertion torque (IT). IT was most influenced by the HU value at 0.5 mm outside the implant placement area, followed by the value within this area, and ISQ by the HU value at 0.5 mm outside the placement area, followed by implant placement site and apical ARW. ISQ values were significantly related to ARW in coronal (P < .05), middle (P < .01), and apical (P < .01) thirds. ISQs were higher with larger-diameter implants (P < .01). ISQ and IT were strongly correlated (P < .001). PIS in terms of ISQ and IT is positively correlated with edentulous alveolar ridge BD measured by CBCT, implying that implant stability may be predicted preoperatively. Wide alveolar ridges favored lateral PIS but did not affect rotational PIS. The most significant predictor of lateral and rotational PIS in our patients was the HU value at 0.5 mm outside the implant placement area.