ABSTRACT
PURPOSE: To analyze the influence of abutment height (AH) on marginal bone loss (MBL). MATERIALS AND METHODS: A literature search was performed for human studies (RCTs, prospective and retrospective cohorts) reporting on AH and MBL. The data obtained-including clinical outcomes, treatment covariates, and patient characteristics-were analyzed. Meta-regression was performed on the effect size of the differences between the shorter and larger AHs on the MBL of each study. The estimation was done using the restricted maximum likelihood method. RESULTS: The initial screening and full-text analysis resulted in 7,936 and 46 articles, respectively. Finally, 14 articles were included in the systematic review, reporting a total of 1,606 implants. An overall high-to-moderate risk of bias was determined among the included investigations. Meta-regression analysis revealed that AH had a significant effect on MBL (b = -1.630, P < .003), demonstrating that longer abutments were correlated with less MBL. No effects were observed for the study type (P = .607), the number of stages (P = .510), or the elapsed time (P = .491). CONCLUSIONS: The height of the abutment has a significant impact on MBL. As such, increased AH is related to less MBL. Nevertheless, the role of confounding variables remains to be studied and determined.
ABSTRACT
PURPOSE: To analyze the influence of abutment height (AH) on marginal bone loss (MBL). MATERIALS AND METHODS: A literature search was performed for human studies (randomized controlled trials, prospective and retrospective cohorts) reporting on the AH and MBL. The data obtained-including clinical outcomes, treatment covariates and patient characteristics-were analyzed. Meta-regression was performed on the effect size of the differences between the shorter and larger AHs on the MBL of each study. The estimation was done using the restricted maximum likelihood method. RESULTS: The initial screening and full-text analysis resulted in 7,936 and 46 articles, respectively. Finally, 14 articles were included in the systematic review, reporting a total of 1,606 implants. An overall high-to-moderate risk of bias was determined among the included investigations. Meta-regression analysis revealed that AH had a significant effect on MBL (b = - 1.630, P < .003), demonstrating that longer abutments were correlated with less MBL. No effects were observed for the study type (P = .607), the number of stages (P = .510), or the elapsed time (P = .491). CONCLUSION: The height of the abutment has a significant impact on MBL. As such, increased AH is related to less MBL. Nevertheless, the role of confounding variables remains to be studied and determined.