| Sumario: | Whether the unfavorable crown-to-implant ratio of extrashort implants and the use of splinted versus nonsplinted crowns affects marginal bone loss and implant survival remains unclear. The purpose of this split-mouth randomized clinical trial was to evaluate the effect of splinting on survival rates and clinical and radiographic parameters associated with prostheses supported by extrashort implants in the posterior region of atrophic mandibles over a 3-year follow-up period. Sixty extrashort implants (5 mm in length) were placed in 10 participants. Prosthesis type for each hemimandible was randomly assigned to 1 of 2 groups (n=30): Group NS, nonsplinted crowns and Group S, splinted crowns. Modified plaque index (mPI), modified sulcus bleeding index (mBI), probing pocket depth (PPD), and vertical marginal bone loss (vMBL) were assessed immediately after prosthesis installation (T0) and at 6 (T1), 24 (T2), and 36 months (T3). A custom-made acrylic resin device was used to standardize radiographic images over time, and vMBL was measured by using an image processing software program. Survival rates were analyzed by using the Kaplan-Meier method and the log-rank test. The Mann-Whitney and Friedman tests were used for mPI and mBI, while 2-way repeated-measures ANOVA was applied for PPD and vMBL (α=.05). No significant difference was observed between groups in terms of survival rates, which were 100% and 96.6% for Groups S and NS, respectively (P =.309). The mPI was significantly higher in Group S than in Group NS at T1 (P <.001) and T3 (P =.006). At T3, Group S also exhibited a significantly higher mBI than Group NS (P =.012). PPD was significantly lower in Group S than in Group NS at all time points (P =.038). No significant difference was found between groups regarding vMBL (P =.498). In both groups, vMBL was significantly higher at T1 than at T3 (P =.035). Extrashort implants with nonsplinted crowns exhibited similar survival rates and vMBL compared with those with splinted crowns over a 3-year follow-up period. Extrashort nonsplinted implants were associated with more effective biofilm control.
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