Vertical ridge augmentation with guided bone regeneration in association with dental implants: an experimental study in dogs

Authors: Simion, Massimo1; Dahlin, Christer2; Rocchietta, Isabella1; Stavropoulos, Andreas3; Sanchez, Raquel4; Karring, Thorkild3

Source: Clinical Oral Implants Research, Volume 18, Number 1, February 2007, pp. 86-94(9)

Publisher: Blackwell Publishing

Abstract:
Aim:

To evaluate the effect of using guided bone regeneration (GBR) with a titanium-reinforced e-PTFE membrane in alveolar bone defects with titanium implants. Material and methods:

Following extraction of three mandibular premolars and a molar on both sides of the jaw in three dogs, alveolar bone defects (depth: 5-7 mm) were produced. After 4 months, three implants were inserted into each defect to a depth of approximately 4 mm, so that their coronal portion was protruding about 5 mm. Four sides in the dogs were assigned to a test group and the remaining two sides to a control group. The 12 implants in the test group were covered with a reinforced e-PTFE membrane. The space under the membrane was filled with peripheral venous blood from the animal, and the flaps were sutured over the membrane. The six control implants received no membrane before the suturing of the flaps to complete wound closure. The animals were sacrificed after 6 months, and non-decalcified histological specimens of the implants and surrounding tissues were prepared. Results:

Histologic and histomorphometric analyses revealed a significantly (Mann-Whitney test; P=0.08) larger amount of bone fill in the test group (mean=57.42%) than in the controls (mean=11.65%), and clinical evaluation of one test site showed that the implants were completely covered with tissue resembling bone. In most of the specimens, bone had grown in height close to, or in direct contact with the membrane. However, the new bone generally was not in direct contact with the implants. Regularly, a zone of dense connective tissue was interposed between the implants and the newly formed bone.

Conclusion:

The formation of even considerable amounts of bone following vertical ridge augmentation with GBR and implants was not accompanied by predictable osseointegration of the implants.

Fully vs. partially rough implants in maxillary sinus floor augmentation: a randomized-controlled clinical trial

Authors: Stavropoulos, Andreas1; Karring, Thorkild1; Kostopoulos, Lambros2

Source: Clinical Oral Implants Research, Volume 18, Number 1, February 2007, pp. 95-102(8)

Publisher: Blackwell Publishing

Abstract:
Objectives:

To compare implants with a rough surface in their whole length (FR) with implants having a 2 mm coronal machined portion (PR) when used in association with a sinus-lift procedure. Material and methods:

Twenty-six patients with 2 mm≤x≤9 mm residual alveolar crest were prosthetically restored with implants after a staged sinus-lift procedure using osteotomes. In 13 randomly chosen patients, no more than one FR implant was placed (test group), while the rest were PR implants. The other 13 patients received only PR implants (control group). For comparisons, only one implant from each patient was used, i.e., from the test group only the 13 FR implants were used, while from the control group, one PR implant was randomly chosen. The presence/absence of plaque, BOP, PPD and REC were registered at the day of delivery of the restorations and after 1 year. Residual alveolar crest height and marginal bone levels around the implants were evaluated on standardized periapical radiographs taken at various stages. Results:

Four FR and two PR implants were lost, and the cumulative survival rate was 82.9% (six lost out of 35). There were no significant differences between the two groups. Implant type, residual alveolar crest height, time of osseointegration, time of implant loading and smoking did not seem to influence implant survival. Conclusions:

FR and PR implants placed in augmented sinuses did not differ in their clinical performance.