Introduction
Dental implant design has significantly evolved to improve long-term stability and reduce complications. Two prominent internal implant-abutment connection types are the conical and internal hex connections. This analysis compares these two designs, examining their impact on marginal bone loss, long-term performance, clinical outcomes, and prosthetic considerations based on recent research findings.
Marginal Bone Loss (MBL)
Short-Term Findings
A 12-month randomized pilot study by Galindo-Moreno et al. reported significant differences in MBL between the two connection types:
- Conical Connections: -0.25 (0.12) mm
- Internal Hex Connections: -0.70 (0.43) mm
However, a larger randomized clinical trial by Esposito et al. found no statistically significant difference in MBL after one year:
- Conical Connections: 0.56 ± 0.53 mm
- Internal Hex Connections: 0.60 ± 0.62 mm (P = 0.745)
Long-Term Findings
A 60-month follow-up study by Sanda et al. demonstrated significantly less MBL in the conical connection group:
- Conical Connections: 0.96 ± 1.02 mm
- Internal Hex Connections: 1.30 ± 1.15 mm
This suggests that, over time, conical connections may be more effective at preserving marginal bone.
2. Clinical Outcomes
Survival Rates
Both connection types show high survival rates, often approaching 100% in short- to medium-term studies.
Complications
A 3-year follow-up study by Siqueira et al. found no significant differences between conical and internal hex connections in terms of:
- Radiographic Marginal Bone Loss (RMBL)
- Gingival Bleeding on Probing
- Implant/Prosthesis Complications
3. Meta-Analysis Findings
A recent systematic review and meta-analysis by Rodrigues et al. compared internal conical connections (ICC) with internal non-conical connections (INCC). The findings were as follows:
- Marginal Bone Loss: ICC showed significantly lower bone loss compared to INCC (Standardized Mean Difference: -0.80 mm; p = 0.004)
- Prosthetic Complications: ICC had a lower risk of prosthetic complications compared to INCC (Risk Ratio: 0.16; p = 0.01)
- Implant Survival Rates: No significant difference was found between ICC and INCC (Risk Ratio: 0.54; p = 0.10)
- Biological Complications: Both connection types showed similar rates of biological complications (Risk Ratio: 0.90; p = 0.82)
4. Conclusion
Current research indicates that both conical and internal hex connection implants perform well in clinical settings. However, recent meta-analysis data suggests that conical connections may offer advantages in terms of:
- Lower marginal bone loss
- Reduced prosthetic complications
The choice between the two connection types should depend on the specific clinical situation, practitioner preference, and individual patient needs. While conical connections may be preferred due to their better preservation of peri-implant bone and lower risk of prosthetic complications, further long-term studies are needed to definitively establish which connection type is superior in various clinical scenarios.
Sources
- Esposito M, Salina S, Rigotti F, et al. A comparison of two implants with conical vs internal hex connections: 1-year post-loading results from a multicentre, randomised controlled trial. Eur J Oral Implantol. 2017;10(2):161-168. https://pubmed.ncbi.nlm.nih.gov/28555206
- Galindo-Moreno P, Concha-Jeronimo A, Lopez-Chaichio L, et al. Marginal Bone Loss around Implants with Internal Hexagonal and Internal Conical Connections: A 12-Month Randomized Pilot Study. Int J Environ Res Public Health. 2021;18(21):11585. https://pmc.ncbi.nlm.nih.gov/articles/PMC8621760/
- Rodrigues VVM, et al. Is the clinical performance of internal conical connection better than internal non-conical connection for implant-supported restorations? A systematic review with meta-analysis of randomized controlled trials. J Prosthodont. 2023 Apr;32(4):637-648. https://pubmed.ncbi.nlm.nih.gov/36700461/
- Camps-Font O, et al. Comparison of external, internal flat-to-flat, and conical implant abutment connections for implant-supported prostheses: A systematic review and network meta-analysis of randomized clinical trials. J Prosthet Dent. 2022;128(4):738-748. https://pubmed.ncbi.nlm.nih.gov/34776267/
- Sanda M, Fueki K, Bari PR, Baba K. Effect of Implant-Abutment Connection Type on Bone Around Dental Implants in Long-Term Observation: Internal Cone Versus Internal Hex. Implant Dent. 2019;28(3):221-224. https://pubmed.ncbi.nlm.nih.gov/31188171/
- Siqueira RAC, et al. Internal Hexagon vs Conical Implant-Abutment Connections: Evaluation of 3-Year Postloading Outcomes. Int J Prosthodont. 2021;34(1):95-101. https://pubmed.ncbi.nlm.nih.gov/33270835/
