Mechanical Stability of the New Modified Tapered and Conventional Tapered Design Implants in the Anterior Maxilla. A Pilot In-Vitro Trial

Abstract

Background: Immediate implant placement in the anterior maxilla has become an increasingly used treatment approach because it may reduce the number of surgical procedures, shorten treatment time, and assist in preservation of the alveolar architecture. Achieving adequate primary stability remains essential for successful implant integration, particularly in extraction sockets where complete implant-to-bone contact may not be present. Implant macro-design, bone density, osteotomy preparation, and insertion technique can influence initial mechanical stability. However, evidence remains limited regarding the comparative performance of different tapered implant designs in simulated anterior maxillary extraction sockets.

Objective: To compare the primary mechanical stability of conventional tapered Osstem TS-III implants and new modified tapered Osstem TS-IV implants placed in simulated anterior maxillary extraction sockets at 1-mm and 2-mm subcrestal depths.

Methods:  This pilot in-vitro experimental study was conducted at BPP Dental Institute using a custom-made drilling system for standardized osteotomy preparation and implant placement from March 2019 till August 2021. This study used ten standardized osteotomies prepared in polyurethane synthetic bone blocks representing D3 bone density. Five conventional tapered TS-III and five modified tapered TS-IV implants, each measuring 4.5 mm in diameter and 11.5 mm in length, were inserted using a standardized custom drilling system. Implant Stability Quotient (ISQ) values were measured using resonance frequency analysis with an Osstell ISQ device from the mesial, distal, buccal, and palatal aspects. Each measurement was repeated three times and averaged. Primary stability was evaluated at 1-mm and 2-mm subcrestal placement depths, and the two implant designs were compared using the Mann–Whitney U test.

Results: The conventional tapered TS-III implants demonstrated greater primary stability than the modified tapered TS-IV implants at both placement depths. At 1 mm, the conventional tapered implants had an overall mean ISQ of 4.60 compared with 1.00 for the modified tapered implants. … The overall Mann–Whitney comparison at 1 mm showed higher mean ranks for TS-III than TS-IV (7.50 vs 3.50; U=2.500), while at 2 mm the corresponding mean ranks were 7.90 and 3.10 (U=0.500. The conventional implant design also generally demonstrated superior stability across the different measurement aspects.

Conclusion: Under standardized in-vitro conditions, the conventional tapered TS-III implant provided greater primary mechanical stability than the new modified tapered TS-IV implant in simulated anterior maxillary extraction sockets. A greater degree of implant taper did not necessarily translate into superior primary stability. Further experimental and clinical investigations are required to determine whether these findings are reproducible in biological bone and clinical immediate implant placement.