Marginal bone changes around platform‐switched conical connection implants placed 1 or 2 mm subcrestally: A multicenter crossover randomized controlled trial

• Published in: Clinical implant dentistry and related research Vol. 25; no. 2; pp. 398 - 408
• Main Authors: Stacchi, Claudio, Lamazza, Luca, Rapani, Antonio, Troiano, Giuseppe, Messina, Marcello, Antonelli, Alessandro, Giudice, Amerigo, Lombardi, Teresa
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-04-2023
• Subjects: Aged; Alveolar Bone Loss - diagnostic imaging; Alveolar Bone Loss - etiology; conical connection; Dental Implantation, Endosseous - methods; Dental Implants; early marginal bone loss; Female; Humans; Male; Middle Aged; Mouth, Edentulous; peri‐implantitis; Prosthesis Implantation; subcrestal implant placement; early marginal bone loss; subcrestal implant placement; conical connection; peri-implantitis
• ISSN: 1523-0899; 1708-8208
• DOI: 10.1111/cid.13186

Introduction
This study analyzes early marginal bone modifications occurring around platform‐switched implants with conical connection placed 1 or 2 mm subcrestally.
Methods
This crossover randomized controlled trial enrolled partially edentulous patients needing two implants in either the posterior maxilla or mandible. Each patient received two platform‐switched implants with conical connection inserted 2 mm (Test) and 1 mm (Control) subcrestally. Definitive abutments were immediately connected and, after 4 months of unsubmerged healing, screwed metal‐ceramic crowns were delivered. Radiographs were taken at implant placement (T0), prosthesis delivery (T1), and after 1 year of prosthetic loading (T2).
Results
Fifty‐one patients (25 males and 26 females; mean age 61.2 ± 12.1 years) totaling 102 implants were included in the final analysis. Mean peri‐implant bone level (PBL) reduction from T0 to T2 was not significantly different around Test (0.49 ± 0.32 mm) and Control implants (0.46 ± 0.35 mm; p = 0.66). Multivariate linear regression models highlighted a significant positive correlation between history of periodontitis and PBL reduction. At T2, no Test group implant and 6 Control group implants exhibited PBL below the implant platform (11.8% of Control group implants).
Conclusion
No significant differences in peri‐implant marginal bone changes were demonstrated after 1 year of prosthetic loading between platform‐switched implants with conical connection inserted either 1 or 2 mm subcrestally. However, 2 mm subcrestal placement resulted in deeper implant positioning at T2, with no exposure of treated implant surface and potential preventive effect against subsequent peri‐implant pathology.