The Association of the One-Abutment at One-Time Concept with Marginal Bone Loss around the SLA and Platform Switch and Conical Abutment Implants

Abstract

Objectives: Repeated abutment disconnection/reconnection may compromise the mucosal barrier and result in crestal bone level changes. The clinical significance of this phenomenon is not yet clear, as most studies on this topic are short-term. Therefore, the aim of the present study was to evaluate the influence of abutment disconnections and reconnections on peri-implant marginal bone loss over a medium-term follow-up period.

Material and methods: Twenty-one patients (6 men and 15 women) with a mean age 66.23 ± 9.35 year at the time of implant placement were included. All patients who received two adjacent nonsubmerged implants were randomly assigned into one of the two groups: definitive multiunit abutments (DEFs) connected to the implant that were not removed (test group) or healing abutments (HEAs) placed at surgery, which were disconnected and reconnected 3-5 times during the prosthetic phase (control group). Peri-implant marginal bone levels (MBL) were measured through periapical X-rays images acquired immediately after the surgery (baseline), at 4-7 months immediately after prosthetic delivery, and at 1-year and 3-year follow-up visits.

Results: No implant was lost or presented bone loss of more than 1.9 mm during the 3-year follow-up; thus, the survival and success rate was 100%. Peri-implant mucositis was noticed in 38.1% DEFs and 41.9% of HEAs at the 3-year follow-up assessment. At the end of 3 years, the MBL was -0.35 ± 0.69 mm for participants in the DEFs group and -0.57 ± 0.80 mm for the HEAs group, with significant statistical difference between groups.

Conclusions: Immediate connection of the multiunit abutments reduced bone loss in comparison with 3-5 disconnections noted in the healing abutments 3 years after prosthetic delivery. However, the difference between the groups was minimal; thus, the clinical relevance of those results is doubtful.

Keywords: connection and disconnection abutment; implant bone loss; implant neck; marginal bone level; platform switch.

Figure 1

(a–c) Maxilla: (a) right upper first premolar and first molar replaced by implants; (b) impression copings of multiunit and healing abutments at 24 weeks; (c) 3-year follow-up.

Figure 1

(a–c) Maxilla: (a) right upper first premolar and first molar replaced by implants; (b) impression copings of multiunit and healing abutments at 24 weeks; (c) 3-year follow-up.

Figure 2

(a–h) Maxilla: (a) Two implants replacing missing right first and second premolars in an 83-year female. The implants shoulder was flushed with the bone. (b) Multiunit (test) and healing (control) abutments were connected after final seating of the implants. (c) Twenty-four weeks after placement, healthy peri-implant keratinized gingiva. (d) Healthy sulcular epithelium at both test (second premolar) and control (first premolar). (e) Transfer adaptation for “open tray “impression technique. (f) Radiographic transfer adaptation. (g) Final crowns at the 3-year follow-up. Opened embrasure spaces for enhanced interproximal plaque control. (h) Radiographic evaluation at the last follow-up (3-year) presents stable crestal bone level in both test and control sites.

Figure 2

(a–h) Maxilla: (a) Two implants replacing missing right first and second premolars in an 83-year female. The implants shoulder was flushed with the bone. (b) Multiunit (test) and healing (control) abutments were connected after final seating of the implants. (c) Twenty-four weeks after placement, healthy peri-implant keratinized gingiva. (d) Healthy sulcular epithelium at both test (second premolar) and control (first premolar). (e) Transfer adaptation for “open tray “impression technique. (f) Radiographic transfer adaptation. (g) Final crowns at the 3-year follow-up. Opened embrasure spaces for enhanced interproximal plaque control. (h) Radiographic evaluation at the last follow-up (3-year) presents stable crestal bone level in both test and control sites.

Figure 2

(a–h) Maxilla: (a) Two implants replacing missing right first and second premolars in an 83-year female. The implants shoulder was flushed with the bone. (b) Multiunit (test) and healing (control) abutments were connected after final seating of the implants. (c) Twenty-four weeks after placement, healthy peri-implant keratinized gingiva. (d) Healthy sulcular epithelium at both test (second premolar) and control (first premolar). (e) Transfer adaptation for “open tray “impression technique. (f) Radiographic transfer adaptation. (g) Final crowns at the 3-year follow-up. Opened embrasure spaces for enhanced interproximal plaque control. (h) Radiographic evaluation at the last follow-up (3-year) presents stable crestal bone level in both test and control sites.

Figure 2

(a–h) Maxilla: (a) Two implants replacing missing right first and second premolars in an 83-year female. The implants shoulder was flushed with the bone. (b) Multiunit (test) and healing (control) abutments were connected after final seating of the implants. (c) Twenty-four weeks after placement, healthy peri-implant keratinized gingiva. (d) Healthy sulcular epithelium at both test (second premolar) and control (first premolar). (e) Transfer adaptation for “open tray “impression technique. (f) Radiographic transfer adaptation. (g) Final crowns at the 3-year follow-up. Opened embrasure spaces for enhanced interproximal plaque control. (h) Radiographic evaluation at the last follow-up (3-year) presents stable crestal bone level in both test and control sites.

Figure 3

Radiographic measurements. (a). Radiographic distortion was calculated by dividing the radiographic implant length by the precise implant length using the measure (line) and calibration function. (b). Marginal bone level (MBL) was measured from the first bone-to-implant contact and implant shoulder.

Figure 3

Radiographic measurements. (a). Radiographic distortion was calculated by dividing the radiographic implant length by the precise implant length using the measure (line) and calibration function. (b). Marginal bone level (MBL) was measured from the first bone-to-implant contact and implant shoulder.

Figure 4

Marginal bone level in healing (red line) vs. multiunit (blue line) abutments at surgery and prosthetic delivery, and at the 1-year and 3-year follow-up evaluations.