Immediately Loaded Implants—Clinical and Biomechanical Analysis

Oral Abstract Session 5 IMPLANTS & TRAUMA Effectiveness of Single-Staged Implant Placement With Simultaneous Grafting Using Mineralized Allograft Bach T. Le, DDS, MD, Los Angeles, CA Statement of the Problem: Horizontal alveolar ridge augmentation using human mineralized allografts to augment localize alveolar ridge defects prior to implant placement has been reported. The purpose of this study is to evaluate the effectiveness of placing implants in a single-staged protocol with simultaneous onlay grafting using particulate human mineralized allograft to augment small alveolar ridge defects. Materials and Methods: This prospective case study evaluated the effectiveness of single-staged implant placement with simultaneous augmentation in 128 patients using a tissue-level implant. Inclusion criteria were healthy patients with a partially edentulous site with Cawood and Howell Class III in need of dental implant therapy to replace missing teeth. Pre-operative computed tomography scans, orthopantomograms and clinical examinations were performed to evaluate ridge form prior to implant placement. Digital photography was used to document and compare pre-operative as well as post-operative results of all implant sites. Surgical procedure involved placement of a tissue-level implant and grafting the labial bone contour defect using mineralized allograft in a single-staged protocol. Methods of Data Analysis: One hundred eight patients completed the study. Using digital photographs, occlusal views were evaluated and ridge forms were judged by an independent clinician. Results were classified as either no difference, improved, or complete correction of defect. The ridges were clinically evaluated 6-12 months after augmentation to determine stability of the peri-implant tissue and bone. Results: Sixty-six patients were judged to have complete correction of ridge contour defects. Thirty-eight patients had improvement in ridge contour defects. Two patients had wound dehiscence with graft exposure requiring secondary surgery. Two patients had to have 2 implants removed due to infection and loss of integration, but were successfully replaced using the same protocol. Twenty patients were lost to follow-up. In all, 156 implants were successfully placed and restored in 108 patients. All implants were integrated and successfully restored. No implants were lost. Mean follow-up was 16 months after implant placement. Clinical and radiographic comparisons show that all augmented ridges had retained their functional and esthetic integrity at 12 months following implant placement and augmenAAOMS • 2009

tation. Minimal resorption was noted with stable crestal bone integrity and a healthy periodontium. Conclusion: Single-staged implant placement with simultaneous grafting with human mineralized allograft is effective in correcting small alveolar ridge defects. This treatment protocol decreases treatment time and procedures for patients without adverse effects. The technique offers predictable functional and esthetic reconstruction of small horizontal alveolar defects. More studies are needed to evaluate the stability of grafted bone after long-term loading. References Le BT, Burstein, J. Cortical Tenting Grafting Technique in the Severely Atrophic Alveolar Ridge for Implant Site Preparation. Implant Dent. 2008; 17(2):140-4 Le BT, Burstein J. Esthetic Grafting for Small Volume Hard and Soft Tissue Defects for Implant Site Development. Implant Dentistry 2008 June 17(2): 136-141

Immediately Loaded Implants—Clinical and Biomechanical Analysis Marcus F. Abboud, DMD, Siegburg, Germany (Rahimi A; Wahl G) Statement of the Problem: The aim is to analyse the clinical and biomechanical results of immediately loaded implants placed in the anterior and posterior region of the maxilla and mandible. Materials and Methods: In-vivo and in-vitro experiments of immediately loaded Ankylos (Friadent GmbH, Mannheim/Germany) and Straumann implants (Institut Straumann AG, Basel/Switzerland) were evaluated. Implants were placed on a regular clinical basis with a provisional crown placed at the same day after surgery. After six weeks implants were restored with a permanent crown or bridge. Periotest measurements and periapical radiographs have been taken at baseline and 3, 6, 12 and 24 months postoperatively. Furthermore Ankylos and Straumann implants in fresh pig jaws have been placed in an optomechanical measuring device, loaded vertical with up to 100N and the movement has been registered by 3 high definition CCD cameras. After that ␮-CT scans of the Ankylos implants in the pig jaws have been performed. The implant surface geometry was reconstructed 3-dimensionally using a self-developed program ADOR3D. With the help of Finite Element analysis simulation of the non-osseointegrated situation was performed with contact analyses: The implant surface was given a certain mobility with respect to the implant bed in the alveolar bone. The osseointegration was simulated by a rigid body contact at the bone/implant interface. 57

Oral Abstract Session 5 The stress, strain, and displacement of the implants after loading are displayed. These results are compared to the bone response in the clinical study. Methods of Data Analysis: Stastical analysis was performed using Excel (Microsoft, Redmond, WA). Differences between the cortical bone level in the various radiographic images at the different time points were determined using a paired t test, with P ⬍ 0.05 regarded as significant. All measurements were performed twice with a time interval in between. Results: 40 patients have been treated in our clinic. The implants’ length ranged from 9.5 mm to 14 mm, with diameters of 5.5 mm (n⫽5), 4.5 mm (n ⫽ 12), and 3.5 mm (n ⫽ 23). The mean change in cortical bone level after 12 months is ⫺0.04 ⫾ 0.51 mm. Marginal bone change ranged from –1.73 mm to ⫹1.01 mm. Increasing density of periimplant bone has been detected after six and twelve months. The recorded Periotest values ranged between 3 and –7. Only minor differences in Periotest measurements occurred over time. 30 days after implant placement no further changes have been detected in all cases. The Finite Element analysis of the Ankylos and Straumann implants placed in the pig jaw correlates with the clinical results, showing loading distribution mainly in the cancellous bone and not in the compacta. The experiments display a safe loading pattern if high level forces are avoided. Measured deflections of the different implants were between 50 and 120 ␮m at a force of up to 100 N. Conclusion: The marginal bone level from the time of implant placement can be preserved. The use of a provisional restoration with an ideal crown form can facilitate the formation of natural contours of the periimplant mucosa. The patients treatment comfort can be significantly enhanced by the immediate loading procedure due to an immediate functional and esthetic reconstruction. The Finite Element analysis results in a good primary implant stability with a homogenous load distribution, helping to preserve the marginal bone level. The results of the Finite Element experiment indicate that immediate loading of implants is a safe procedure in the correct indication and with controlled loading forces. References Degidi, M., Piattelli, A., Felice, P. & Carinci, F. (2005) Immediate functional loading of edentulous maxilla: a 5-year retrospective study of 388 titanium implants. Journal of Periodontology 76: 1016 –1024 Glauser R, Sennerby L, Meredith N, Ree A, Lundgren A, Gottlow J. Resonance frequency analysis of implants subjected to immediate or early functional occlusal loading. Successful vs. failing implants. Clin Oral Implants Res 2004;15:428-434

The Reliability of Radio Frequency Analysis (RFA) in Determining Surgical Placement and Loading Protocols of Endosseous Implants Moustafa H. El-Ghareeb, BDS, MS, Los Angeles, CA (Aghaloo T; Yong L; Hameed S; Jimenez D; Moy P) 58

Statement of the Problem: While radio frequency analysis (RFA) has been used to evaluate the stability of dental implants, there has been no clear correlation between values obtained and clinical outcomes, ie survival or failure. To date there is no clear cut-off value to guide clinicians in the selection of implant surgical placement or loading protocols. This study determines the reliability of RFA and validates cut-off values in determining the surgical placement and loading protocols. Materials and Methods: The stability of implants of various systems, placed by a single oral and maxillofacial surgeon in 2002-2007, was evaluated using RFA and assigned an implant stability quotient (ISQ) value. 913 implants with ISQ values taken at the time of placement were assigned to one-stage or two-stage based on the operator’s subjective assessment. An arbitrary cut-off ISQ value of 50 was selected and implant survival analyzed accordingly. In 1247 implants assigned to either early or traditional loading, ISQ values at osseointegration were correlated to clinical outcome. With an arbitrary ISQ value of 50, survival or failure was analyzed to determine true positives, true negatives, false positives and false negatives. Methods of Data Analysis: Data was analyzed using sensitivity, specificity, positive and negative predictive values. Results: Implants placed as two-stage had a 100% survival rate irrespective of the ISQ value. Implants placed as one-stage with ISQ values ⱖ 50 had a 97.8% survival rate and the rate dropped to 82.4% when the cut-off value was not observed and implants were placed with a one-stage protocol at ISQ values ⬍ 50. In 905 implants traditionally loaded, 94.4% were true positive, 2.3% were false positive, 3% false negative and 0.3% true negative. In 342 implants early loaded, 99.9% were true positive, 0.6% were false positive, 0.3% false negative and 0% true negative. Conclusion: The cut-off ISQ value of 50 was validated in this study and should warn the surgeon to abort a one-stage protocol when a low ISQ value is obtained at the time of placement. It is predictable to early load implants with ISQ values of ⱖ 50 due to the high success rate found in this study. With the low incidence of false positives in traditional and early loading protocols, RFA is reliable and is a valid prognostic indicator of success. References Quantitative determination of the stability of the implant-tissue interface using resonance frequency analysis. Meredith et al. Clinical Oral Implants Research 7: 261-7, 1996 Resonance frequency measurements of implant stability in vivo. A cross sectional and longitudinal study of resonance frequency measurements on implants in the edentulous and partially dentate maxilla. Meredith et al. Clinical Oral Implants Research 8:234

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