Dott. Daniele Cardaropoli
Private Practitioner,Turin,Italy

Dott. Roberto Abundo
Assistant Professor in Periodontology-University of Turin(Dental Clinic,S.Luigi Gonzaga Hospital-Orbassano) A.P.O.R. Cultural Secretary

Dott. Giuseppe Corrente
Assistant Professor in Periodontal Surgery- University of Turin(Dental Clinic,S.Luigi Gonzaga Hospital-Orbassano) A.P.O.R. President

Follow-up of osseointegrated implants with bone regenerative procedures.
(Abstract from Daniele Cardaropoli’s Graduation Thesis, University of Turin, Dental School; Turin, 7/11/1996)

Abstract
In the present study in 45 patients 173 fixtures were inserted, 81 of which presented periimplant bone defects and regenerative procedures were performed while 92 had adequate bone volume. Each one of the patients received at least one implant with regenerative procedures and one implant in standard conditions. At the surgical reentry complete/incomplete bone defects fillings were registered.The success rate for implants inserted in standard conditions was 95.6% (mean follow-up of 26 months) while the success rate of implants inserted with GBR procedures was 93.3%(mean follow-up of 23 months). Among this group, implants that reached a complete bone defects filling had a success rate of 98.4% while 63.6% was the success rate in case of incomplete bone defects filling.The results suggest that long-term predictability of bone augmentation techniques, once obtained the complete periimplant defects filling, is comparable to that of implants inserted in adequate bone volume.

Introduction
Due to the scientific studies of various authors such as Brånemark[1] and Schroeder[2], the use of dental implants has become widely accepted(with a success rate of over 85% in a 5-years follow-up) for the substitution of missing teeth in partially or totally edentulous patients. A restriction for the use of this technique was the need of alveolar ridges with an adequate bone volume to receive the submerged implants.

In the last few years several authors have used Guided Bone Regeneration, i.e. reconstructive surgery techniques utilized to extend the use of dental implants also in patients with unfavourable anatomical conditions [3][4][5][6]. In this way, using the previous experiences of Orthopedics [7][8]and Periodontology [9][10][11][12][13],it is possible to resolve such cases in which the ideal prosthetic placement of the implant doesn’t correspond to the site where the bone necessary to the insertion of fixture is.

Besides, the use of osseointegrated implants not only to support overdentures but also in partial edentulism has stimulated the development of new techniques suitable for reaching the best aesthetic results.

GBR allows today to consider no more negative such conditions in which a periimplant bone defect remains after the fixture insertion,due to the possible growth of newly formed bone . The state of the art shows several techniques used separately or in association to obtain an optimal bone regeneration. Aim of these procedures is to affect positively the long-term preservation of osseointegration also when the clinical and radiological pre-surgical evaluation shows few possibilities of success. Various techniques have been presented to clinically apply the GBR principles, such as the use of resorbable and non-resorbable membranes, autologous and eterologous bone grafts and alloplastic materials.

The purpose of the present study is to evaluate the influence of various regenerative procedures on the long-term behaviour of endosseous implants comparing these results with that of implants inserted in standard conditions.

Materials and methods
45 patients with indications to the insertion of implants were selected. In this group of patients 173 implants were inserted between October 1991 and December 1994(119 in the upper jaw and 54 in the lower jaw). 81 of them showed periimplant bone defects after their insertion and bone regenerative procedures were performed at the same time of first surgical stage, while 92 implants were inserted in standard conditions, i.e. they were sorrounded by preexisting bone.

Implants used in this study were 112 Screw-Vent (Dentsply, USA), 45 Ha-Ti (Mathys, Switzerland), 16 Eta System (Biaggini Ormco,Italy).

The surgical protocol was as follows: incision and elevation of a full-thickness flap, preparation of the implantation site following the surgical protocol suggested from the costumer,insertion of the implant,use of regenerative procedures where a bone defect remained after the insertion, suture of the flap.

Each one of the patients received at least one implant with regenerative procedures (test) and one implant in standard conditions (control),for a total of 81 test implants and 92 control implants.

The procedures used were the following:

• calcium carbonate allograft(Biocoral Gel,Inoteb,France) in 50 cases
• calcium carbonate and fibrin-fibronectin sealing system (Tissucol, Immuno,Austria) in 10 cases
• autologous bone in 7 cases
• tricalcium-phospate allograft (Ceros TCP,Mathys,Switzerland) in 4 cases
• calcium carbonate and poliglycholic acid membrane (Biofix,Bioscience,Finland) in 4 cases
• autologous bone and poliglycholic acid membrane in 3 cases
• e-PTFE membrane (GTAM,WL Gore & Ass,USA) in 3 cases.

Patients rinsed with chlorexidine 0.12% twice a day for 12 days and took amoxicyllin 1 gr every 8 hours plus nimesulide 100 mg every 12 hours for 7 days.

Sutures were removed after 12 days.

In the waiting time patients were controlled every 4 weeks,evaluating clinical symptoms and the aspect of the periimplant mucosa;in the same period periapical radiographs were taken.

All the implants inserted with regenerative procedures both in the maxilla and in the mandibula had the second surgical stage after 6 months.For implants inserted in standard conditions 3 months were waited in the mandibula and 4 months in the maxilla.

At the second surgical stage complete/incomplete bone defects fillings were registered.

All implants then received prosthetic reconstruction.

Clinical and radiographic controls were performed every six months in order to evaluate fullfilling of success criteria according to Albrektsson[14]

Among periimplant regeneration group, success rate of implants showing complete bone defect filling at the second surgical stage was compared to that of implants showing incomplete filling. Statistical analysis was made by means of Fisher exact 2-tailed test. Also success rates of the various regenerative techniques were compared by means of Fisher exact 2-tailed test.

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