Accuracy of virtually planned and template guided implant surgery on edentate patients.

PURPOSE: Scientific evidence regarding the accuracy of implants placed into patients by the aid of a surgical template is limited. The objective of the present study was to verify if any variation exists between virtually planned implants' position using a computer, compared with the subsequently clinically placed implants with the aid of a surgical template in the mandible and the maxilla. MATERIAL AND METHODS: A total number of 25 edentate jaws were treated with the aid of a surgical template. In total, 139 implants were inserted. Fifty implants were inserted in the mandible and 89 in the maxilla. A voxel-based registration method was used to match two separate cone-beam computed tomography scans of the patients. The implant positions were calculated and compared between the planned implants and the implants' clinical position after more than 1 year after surgery. The results included the linear differences in distance at the level of the hex, the apex, and the depth. The angular differences were presented in degrees. RESULTS: Statistical results indicated some factors with significant deviations. The greatest errors were found when comparing between patients moving during the computed tomography scans and those that did not move. The results showed significant divergence at the level of the hex and apex of the implants. CONCLUSION: The hypothesis was rejected, as the statistical results indicated that there were significant differences between virtually planned implants' position and the final position of implants placed clinically.

Accuracy and complications using computer-designed stereolithographic surgical guides for oral rehabilitation by means of dental implants: a review of the literature.

BACKGROUND: In the last decade several stereolithographic guided surgery systems were introduced to the market. In this context, scientific information regarding accuracy of implant placement and surgical and prosthodontical complications is highly relevant as it provides evidence to implement this surgical technique in a clinical setting. PURPOSE: To review data on accuracy and surgical and prosthodontical complications using stereolithographical surgical guides for implant rehabilitation. MATERIAL AND METHODS: PubMed database was searched using the following keywords: "three dimensional imaging,""image based surgery,""flapless guided surgery,""customized drill guides,""computer assisted surgery,""surgical template," and "stereolithography." Only papers in English were selected. Additional references found through reading of selected papers completed the list. RESULTS: In total 31 papers were selected. Ten reported deviations between the preoperative implant planning and the postoperative implant locations. One in vitro study reported a mean apical deviation of 1.0 mm, three ex vivo studies a mean apical deviation ranging between 0.6 and 1.2 mm. In six in vivo studies an apical deviation between 0.95 and 4.5 mm was found. Six papers reported on complications mounting to 42% of the cases when stereolithographic guided surgery was combined with immediate loading. CONCLUSION: Substantial deviations in three-dimensional directions are found between virtual planning and actually obtained implant position. This finding and additionally reported postsurgical complications leads to the conclusion that care should be taken whenever applying this technique on a routine basis.

Soft tissue conditions and marginal bone changes around immediately loaded implants inserted in edentate jaws following computer guided treatment planning and flapless surgery: a ≥1-year clinical follow-up study.

BACKGROUND: Evaluation of the clinical conditions following computer guided treatment planning and flapless surgery is still limited. OBJECTIVES: The objective was to evaluate the soft tissue conditions and marginal bone changes after 1 year of function around immediately loaded implants inserted in edentate jaws following computer guided treatment planning and flapless surgery. MATERIAL AND METHODS: Twenty-nine edentate jaws (19 maxillae, 10 mandibles) treated with 165 implants using the Teeth-in-an-Hour™ protocol were included. In these patients, peri-implant soft tissue conditions and radiographic marginal bone changes were evaluated after ≥1 year of functional loading (mean: 19 months). RESULTS: The mean probing depth at case level was 2.6 mm (SD: 0.6). Bleeding on probing was recorded as a mean of 81.9% (SD: 23.0). Plaque index showed a wide range of 0-100%. The mean marginal bone change of measured sites evaluated on intraoral radiographs was -1.2 mm (SD: 1.4). A marginal bone loss more than 1.5 mm or 2.0 mm was observed in 42% and 27% of the measured sites, respectively. A pressure-like-ulcer was found in 9 cases. Implants with marginal bone loss of >1.5 mm were more frequently observed in cases with an ulcer than cases where no ulcer was found. CONCLUSION: Although the mean marginal bone loss after function in the present study was within the range of other reports presenting mean bone loss data after immediate implant loading, our patients showed a wide range of bone loss with several sites, where the bone loss was greater than the commonly used successful level (>1.5 mm).

Virtually planned and template-guided implant surgery: an experimental model matching approach.

OBJECTIVES: The objective of this study was to assess positional deviations between the implant replicas in the pre-operative plaster model created from a computer-aided design/computer-aided manufacturing (CAD/CAM) surgical template and the implant replicas in the post-operative plaster model that was made from patients' impressions taken at ≥1-year follow-up. MATERIAL AND METHODS: One hundred and thirty-nine implants were inserted in 25 edentulous jaws using Nobel Guide(™). Plaster models containing the implant replicas, one created from the surgical template before surgery and the other created from patients' impressions at ≥1-year follow-up, were scanned using a measuring device. Implant positions were matched with the best-fit alignment. Deviation was calculated at the level of the hex and the apex. The results were compared with a computed tomography matching study. Data were analysed using the paired t-test (α=0.05). RESULTS: There were positional deviations of implant replicas between pre- and post-operative plaster models both at the hex and the apex. The geometric mean of the deviation at the apex was 0.59 mm in the maxilla and 0.4 mm in the mandible. At the hex, it was 0.59 mm in the maxilla and 0.39 mm in the mandible. CONCLUSIONS: Statistically significant differences were observed in positions between the implant replicas in the pre-operative plaster models created from a CAD/CAM surgical template and the implant replicas in the post-operative plaster models that were made from patients' impressions taken at ≥1-year follow-up. Due to the lack of reference objects in the pre- and post-operative working casts, additional refinements are required in order to validate the impression matching method and recommend the method to be used.

Treatment outcome of immediately loaded implants installed in edentulous jaws following computer-assisted virtual treatment planning and flapless surgery.

OBJECTIVES: The objective was to evaluate the outcome of immediately loaded implants installed in edentulous jaws following computer-assisted virtual treatment planning combined with flapless surgery. MATERIAL AND METHODS: Twenty-nine edentulous patients (9 females, 20 males, mean age of 71.5 years) were treated using the Nobel Guide protocol for surgical planning, fixture installation and immediate functioning of a prefabricated fixed implant prosthesis. One hundred and seventy-six fixtures were installed to support 21 maxillary and 10 mandibular reconstructions. Patients were followed for up to 44 months. RESULTS: Nineteen out of 176 fixtures were lost between 2 and 18 months after installation. Fixture survival rate was 89% (92% maxilla, 83% mandible). Implant-supported suprastructures remained stable during the follow-up period in 26 out of 31 jaws (90% maxilla, 70% mandible). Surgical or technical complications occurred in 42% of treated cases. Misfit of abutment-bridge appeared in five cases, resulting in disconnection of the bridge in two patients where fixtures were left for unloaded healing. Fixture losses resulted in the removal of the suprastructure in three patients, who returned to removable dentures. Extensive adjustments of occlusion were made in 10% of the immediately connected bridges. Radiographic bone defects developed in three patients after drilling, which appeared in two cases after anchor-pin drilling in the maxilla and another in a severely resorbed mandible. CONCLUSION: The patient's post-operative discomfort such as swelling and pain was almost negligible. However, compared to conventional protocols, the occurrences of surgical and technical complications were higher, and thus this method must still be regarded to be in an exploratory phase.

Supportive therapy and the longevity of dental implants: a systematic review of the literature.

OBJECTIVE: To review systematically whether supportive implant treatment during a follow-up of at least 10 years after functional loading is effective in prevention of biological complications and fixture loss. METHODS: A MEDLINE search was conducted for the period of 1965 to April 2006 of longitudinal clinical studies with follow-up periods after implant function of at least 10 years. Sixty-two studies were initially screened for inclusion and read in full text. Nine studies remained for the final assessment and 53 articles were thus excluded for the following reasons: (1) no information on implant maintenance was presented, (2) the number of patients/implants assessed at 10-year follow-up/final evaluation was not presented (3) fixture loss and marginal bone loss during function were not assessed at 10-year evaluation and (4) residual inflammation and/or probing pocket depth (PPD) not assessed at 10-year examination. RESULTS: Fifty-six percent of 62 initially screened studies did not assess clinical inflammation and PPD around implants at long-term evaluation of implants. This was the most common reason for exclusion of studies. In 28% of excluded studies, there was no information on implant maintenance during follow-up. A total of 749 fixtures were included and followed for more than 10 years of functional load. Five of the included studies gave no detailed information of the assessments or the treatment at follow-up visits during the 10 years. Only in two of the included cohorts were patients enrolled in an individualized supportive program on a 3-6-month recall interval. CONCLUSION: There are, to date, few available studies evaluating the long-term effect of supportive programs for implant patients. Based on the nine studies included, no evidence is available to suggest the frequency of recall intervals or to propose specific hygiene treatments. There is an urgent need for such studies to be initiated.