The Role of Different Healing Abutment Sizes in Tissue Volume Preservation of Molar Sockets After Immediate Tooth Extraction and Implant Placement: A Multicenter Clinical Study

Purpose: To evaluate the role of different healing abutment designs in compensating for the buccolingual volumetric tissue change that occurs following flapless single-tooth immediate extraction placement in the molar area. Materials and Methods: Patients in need of extraction and replacement of a first or second molar in the mandible or maxilla were consecutively recruited. Immediately after extraction and implant placement, an abutment was connected. Five different types of abutments were randomly selected to be used for each case. The study population was divided into five categories according to abutment design: 5-mm diameter healing abutment (group 1); 6-mm diameter healing abutment (group 2); 7.5-mm diameter healing abutment (group 3); provisional restoration (group 4); and customized healing abutment (group 5). The buccopalatal dimension (BPD) was measured on the study casts at 1, 3, and 5 mm apical to the free gingival margin, and horizontal volumetric changes were compared between baseline and 2, 4, and 6 months. Results: A total of 267 implants were inserted in 246 patients. The breakdown of placed implants for each group was as follows: 67 implants in group 1; 64 in group 2; 71 in group 3; 33 in group 4; and 32 in group 5. Changes in the mean horizontal ridge dimension were as follows. After 6 months in group 1, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 4.21 +/- 0.158, 3.38 +/- O.178 and 2.35 +/- O.178 mm. In group 2, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 3.16 +/- 0.198, 2.56 +/- 0.198, and 1.62 +/- 0.198 mm. In group 3, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 2.53 +/- 0.138, 2.16 +/- O.144, and 1.56 +/- O.144 mm. In group 4, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 1.11 +/- O.179, 1.23 +/- O.179, and 1.12 +/- O.179 mm. In group 5, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by O.25 +/- O.225, 0.30 +/- O.225, and 0.19 +/- O.225 mm. Mixed-effect regression and post hoc means comparisons were used to model the impact of the restoration technique, height of measurement, and time on BPD using a significance reference level of .05. Statistical analysis showed that the type of abutment, the height of measurement, and the time significantly influenced the BPD and that there were complex interaction effects between these variables. Conclusion: The observed volumetric soft tissue changes in the 6-month short-term follow-up appeared to vary based on the use of different healing abutment sizes that were connected to implants placed immediately after tooth extraction in the molar area. In particular, the use of a customized healing abutment resulted in preservation of the original horizontal dimension of the molar soft tissue.