In Vitro Evaluation of the Primary Stability of Short Implants in Different Surgical Techniques

Effect of Residual Bone Height and Implant Macro-Design on Primary Stability in Sinus Floor Elevation: An Ex Vivo Study

The objective was to evaluate the influence of residual bone height (RBH) and implant macro-design on the primary stability (PS) of implants using a simultaneous sinus floor elevation (SFE) and implant insertion model. Fresh bovine rib samples that resembled type-IV density that were confirmed by computerized tomography were prepared to represent 4 groups of varying RBHs (3, 6, 9, 15 mm). To simulate simultaneous implant insertion with SFE, 120 implants in different macro-designs (group R: NobelReplace; group P: NobelParallel; group A: NobelActive, Nobel Biocare, Gothenburg, Sweden) were randomly inserted at RBHs of 3, 6, 9, and 15 mm in each rib. The implant stability quotient (ISQ) was measured immediately after implant insertion. RBH and implant macro-design have an impact on ISQ values (P < .001). ISQ values were the highest with RBH of 15 mm, followed by RBHs of 9, 6, and 3 mm. (P < .001). There was no statistically significant difference between different implant macro-designs at RBHs of 3 and 15 mm regarding ISQ values (P = .111, P = .551). ISQ values of group P were higher than those of group R and group A at an RBH of 6 mm (P = .049, P = .029). ISQ values were also higher in group P compared to group A at an RBH of 9 mm (P = .006). A higher PS may be expected in sites with higher RBH, regardless of the macro-design. In addition, cylindric implant design may enhance the PS at RBHs of 6 and 9 mm in simultaneous implant insertion with SFE.

Posterior jaws rehabilitation with < 7mm-short implants. A review

INTRODUCTION

The results with shorter and shorter implants have been revolutionizing the implantology scenario and are worthy of being well-analyzed and understood. This review aims to add further knowledge about the last 10-years observation period on < 7mm-short implants in the posterior atrophic jaws, better defining the indication of their use.

METHODS

From a Medline database research, systematic reviews, controlled and no- controlled trials (CT, n-CT) with ≥ 3years-follow-ups on <7 mm / ≥ 5mm-short implants (group A), and clinical studies with ≥ 1year-follow-up on 4mm-short implants (group B) were considered. The outcomes, in terms of implant survival rate (SR), marginal bone loss (MBL), and complications were analyzed according to the duration of follow-ups, implant site (maxilla and mandible), type of prosthesis (single crown or splinted units), vertically impaired or normal sites.

RESULTS

Thirty-four trials (28 for group A and six for group B) were selected. Group A: a mean follow up of 5,8 (3-10) years came out; pre-and post-loading SR range was 94.4- 100% and 89.6-100%, respectively; the range of MBL was 0.12-1.49; 50% of CT found less statistically significant surgical complications in comparison with standard implants (ST) in reconstructed sites, while major prosthetic problems were recorded with short -implants (SH) in 37.5% of CT; in no atrophied sites, a mean SR range of 86.7-100 % vs. 88-100 % and a total bone loss of 2 vs.1.6 for SH vs.ST emerged. Group B: the overall mean follow-up period was 2,3 years, and the pre-and post- SR ranges were 93-100 % and 87.5-100 %, respectively. The MBL range was 0.02- 0.63 mm. All RCT reported significantly fewer surgical complications with SH than with ST in reconstructed mandibles within one year. No prosthetic complications were reported for up to 5 years using no pontics or cantilevers fixed bridges.

CONCLUSIONS

Similar or even better results for SH than ST in terms of post-loading SR and MBL came out for < 7mm/ ≥ 5mm-short implants in atrophic bone regardless of the prosthetic solutions, with less surgical complications but a few more prosthetic problems; the good results up to 5 years for 4mm-short implants in mandibles are associated with splinted and no-risk prosthetic solutions.

A 4 mm-Long Implant Rehabilitation in the Posterior Maxilla with Dynamic Navigation Technology: A Case Report after a Three-Years Post-Loading Follow-Up

The use of short (<8 mm long) and ultra-short (<6 mm long) implants allows the prosthetic rehabilitation of the posterior ridges of the jaws avoiding reconstructive procedures. Nevertheless, this approach requires vast experience to ensure the primary stability of the fixture in a correct position. Computer-aided implantology (CAI) achieves better results than the free-hand one in terms of placement accuracy, reducing the surgical risks and the operative timings. Dynamic navigation (DN) allows the surgeon to track the position and movements of the drill in real-time on the CT imaging data set. It is more versatile than the computed static system, enabling the operator to change the guidance coordinates according to the intra-operative feedbacks. A mono-edentulous upper right first molar site was rehabilitated with a four mm-long implant to avoid reconstructive techniques, drastically rejected by the patients. The case was managed within a DN protocol considering the minimal available bone and the prosthetic demands. The phases of this procedure were strictly documented up to a 3-year follow-up. No intra-operative problems occurred, and adequate primary stability of the implant was obtained. The prosthetic loading was carried out within only six weeks without any complications. No variation of the baseline clinical scenario as evidenced clinically and radiographically at the end of follow-up. No similar cases are reported in the literature.