Extra-short Implants Research Articles

Retrospective Study of Short and Extra-Short Implants Placed in Posterior Regions: Influence of Crown-to-Implant Ratio on Marginal Bone Loss

The aim of this study is to evaluate the influence of crown-to-implant (CI) ratio as well as other surgical, prosthetic and biomechanical variables on marginal bone loss (MBL) and on the survival rates of implant-supported prostheses in short implants (≤8.5 mm in length) placed in posterior areas of maxilla and mandible. This was a retrospective study based on clinical charts and follow-up recordings from a single private practice over a period of 10 years. Patients rehabilitated in the posterior region of the jaws by means of prostheses supported by implants of ≤8.5 mm length were included. Patients-related, surgery-related. and implant-related variables, as well as other prosthetic and biomechanical variables. were registered. The data were split into two groups according to the value of CI ratio (CI < 2 and CI ≥ 2). MBL was measured from radiographs using an image analysis software. Implant and prosthesis survival rates were recorded. One hundred twenty-eight short implants placed in 63 patients were evaluated. The mean follow-up period was 21.88 months (standard deviation (SD): 22.9, range 7-113 months). Eighty-six implants (67.2%) had a CI ratio of <2, whereas it was ≥2 in 42 implants (32.8%). The mean value of CI ratio was 1.82 (SD: 0.42; range 1.04-3.31). The average MBL after 1 year of follow-up was 0.35 (SD: 0.50), and it was 0.45 (SD: 0.46) mm for subsequent evaluations. Survival rates of implants and prosthesis were 100%. The presence of a cantilever had a negative influence on the first year MBL (p < .05). The CI ratio had not a significant influence on MBL in Biotechnology Institute (BTI; Vitoria, Spain) short implants humidified with PRGF-Endoret and placed in posterior areas. The only variable that showed a significant negative influence on first year postloading MBL was the use of cantilever for rehabilitations.

Novel Technique for the Treatment of the Severely Atrophied Posterior Mandible

To present a new technique for the rehabilitation of the severely atrophied mandible that avoids the need for advanced surgical reconstruction. Severe resorption in the posterior mandible was treated following a conservative approach. A novel drilling technique and vertical implant-guided bone regeneration were performed to insert extra-short implants for maximum use of the bone above the mandibular canal. A progressive loading protocol was followed for the prosthetic rehabilitation with screw-retained prostheses. During the follow-up period, surgical complications, prosthetic failures, marginal bone loss, and implant survival were monitored. The described conservative approach was effective in patients with residual bone height above the mandibular canal that was often less than 6 mm. No signs of sensory disturbances or nerve injury were detected during the observation period. One hundred fourteen extra-short implants were inserted in 72 patients, with a mean follow-up period of 26 months after implant insertion. The implant survival rate was 98.2% (two implants failed). Proximal bone loss was limited to 1 mm, and detailed analysis of factors influencing bone loss indicated that the increase in implant diameter was associated with a tendency toward decreased bone loss. Prosthetic complications (eg, fracture or screw loosening) were not observed in this study. This minimally invasive approach contributed to successful oral rehabilitation of patients with severely atrophied posterior mandibles. The development of conservative approaches will decrease the risk of surgical morbidity, save money and time, and decrease the complexity of surgery.

Extra short dental implants supporting an overdenture in the edentulous maxilla: a proof of concept

This study investigates the outcome of short implants additionally placed with longer implants to support a maxillary overdenture. Twelve patients received six implants to support a maxillary overdenture. Only one patient still had two molars in the maxilla, while the others had no remaining teeth. The status of the opposing arch was diverse. The distal implant in each quadrant was 6 mm in height (S) and the middle implants ranged between 10 and 14 mm (L). All implants were placed following a one-stage procedure and early loaded (6 weeks). Clinical and radiological parameters were assessed 6, 12 and 24 months after loading. One short implant failed 2 weeks after surgery, probably due to early mobilization by the provisional prosthesis. The mean bone loss on the rough part of the implant was 0.7 mm (S) vs. 1.3 mm (L) during the first year and 0.3 mm (S) vs. 0.2 mm (L) during the second year after loading. The mean implant stability quotient values were 67 (S) vs. 70 (L) at placement and 75 (S) vs. 78 (L) after 1 year. At the 2-year follow- up, all prostheses were still stable and comfortable. An overdenture on six implants, of which two have a reduced length, might represent a successful treatment option. No significant difference could be found between both implant lengths at 2 years' follow-up. However, bone loss with short implants may increase the likelihood of failure.