Conditions for success in guided bone regeneration: retrospective study on 376 implant sites

BACKGROUND

Used alone or in association with bone, guided bone regeneration is a clinically accepted method to increase the volume of bone during implant placement. Concerns about appropriate surgical techniques and the predictability of the results questions still exist. The aim of this study was to assess the conditions for success.

METHODS

Three-hundred-seventy-six implants were placed in association with 214 non-resorbable membranes. In 109 implants, the membrane was secured on a blood clot; for 213 implants, membrane was placed with autogenous bone; and for 54 implants it was placed with allogenic bone. The surgical procedure, the primary closure, the timing of re-entry, and the density of regenerated tissue were studied.

RESULTS

In 19 membranes, barrier exposure occurred before 3 months in these instances, the regenerated tissue was removed; another 7 membranes were exposed between 3 and 6 months. The 188 non-exposed membranes were removed between 6 and 12 months. In cases of exposure before 3 months, the regenerated tissue was soft and then removed. After closure for 6 months or more, the regenerated tissue was dense and resistant to probe pressure. The best results were obtained when the membranes were placed with autogenous bone.

CONCLUSIONS

If all the clinical steps are appropriately followed, guided bone regeneration using an autogenous bone graft and implant placement is a predictable technique for increasing bone volume.

Clinical evaluation of guided bone regeneration at exposed parts of Brånemark dental implants with and without bone allograft

This investigation evaluated guided bone regeneration with a polytetrafluoroethylene barrier membrane at exposed parts of Brånemark dental implants with and without concomitant use of decalcified freeze-dried bone allograft. Density of the regenerated tissue was also determined using a No. 23 probe at a pressure of 25 g and was graded from 1 to 5. The higher index was associated with a higher resistance of newly formed tissue to the pressure of the probe. In 19 patients, 23 defects were treated by barrier membrane alone and 11 defects by bone allograft with barrier membrane. The width and the depth of the defects were determined at the time of the implant placement and at the second-stage implant surgery. When success was defined as 0 mm of residual defect, the mean success rate was 68% for the membrane group and 90% for the membrane group with bone allograft, with no statistically significant difference between the two treatment groups. The two groups did not demonstrate a significant difference in median density index. There was a significant positive relationship between time of membrane coverage and density index. A density index of 4 was only recorded after 7 months of membrane coverage. The present findings suggest beneficial clinical effect with the use of membrane alone and freeze-dried bone allograft with membrane for guided bone regeneration. This study proposed the use of a novel density index for clinical evaluation of regenerated tissue.

[Periodontal reconstruction using the guided tissue regeneration technique. Apropos of a case]

Different surgical techniques have been used to treat periodontal osseous defects. Periodontists were very full of hope with osseous grafts but the results were disappointing or unpredictable. A best knowledge of the biologics determinants of periodontal healing has lead to the concept of guided regeneration. A case of deep osseous defect of a mandibular incisor was treated by the placement of a Gore Tex membrane. The clinical and radiographic result is satisfactory.

Repair potential in localized juvenile periodontitis. A case in point

An aggressive form of localized juvenile periodontitis (LJP) in a 12-year old West African female is reported. The case was treated with scaling, root planing, debridement, and tetracycline therapy, which resulted in complete resolution of the disease, including elimination of periodontal inflammation, regeneration of lost periodontal structures, and spontaneous repositioning of teeth that had pathologically migrated. A hopelessly involved mandibular right first molar was successfully replaced by an incompletely developed maxillary third molar tooth bud whose roots and pulp structure continued to develop after autotransplantation. It is suggested, that LJP can be successfully treated without periodontal surgery and that the potential for repair in LJP cases is apparently greater than what one can anticipate in adult forms of periodontitis.

[Function of polynuclear neutrophils in patients with juvenile periodontitis and rapidly progressing periodontitis]

It is generally assumed that early onset forms of periodontal disease (including Juvenile and Rapidly Progressive Periodontitis) are associated with a defect in neutrophil behaviour. We have investigated neutrophil functions in patients with Juvenile (J.P.) and Rapidly Progressive Periodontitis (R.P.P.). In the group of J.P. patients the directed mobility (FMLP and zymosan activated plasma) is significantly decreased. The superoxide generation in response to FMLP decreases while the PMA response is normal. In the group of R.P.P. patients no significant abnormality has been reported.

[Guided tissue regeneration: clinical and microscopic study]

A case of furcation involvement of a maxillary molar is reported. The treatment consisted in applying the concept of Controlled Tissue Regeneration using a Goretex membrane. After removal of the membrane the result is satisfactory. The membrane is then examined under transmission electronic microscope. The lateral aspect of the membrane (in contact with the proliferating epithelial tissue) show a marked bacterial proliferation.

[Histological study of periodontal healing of surgically displaced human teeth]

Mandibular incisors had to be extracted on a 52 years old patient. The aim of this investigation was to study, the periodontal healing of teeth surgically displaced after bone resections (alveolar, buccal and apical). 3 years later, the teeth were extracted and treated for microscopic observation. No new attachment was seen on the curetted roots, except where the periodontal ligament had been preserved. The concept of cellular sociology was suggested to explain the sites of radicular resorption. An hypothesis was then put forward: epithelial formations present in the periodontal ligament are not of an embryologic origin (Malassez debris) but are issued from the migration of epithelial cords during new formation of the junctional epithelium.

[Cellular competition and healing]

Different therapeutic solutions have been tried to obtain a new attachment. Several animal experiments have studied cellular colonization of radicular surfaces exposed to the disease then planed. Only the cells from the periodontal ligament seem to be able to form a new attachment. The interposition of a membrane seem to prevent gingival and osseous tissues to interfere with the periodontal ligament. The periodontal ligament cells colonize then the radicular surface.

[Current therapy of gingival recession]

The muco-gingival surgery represents one of the facet of periodontal surgery. The gingival recessions, characterized by a total attachmentless uncovering the root surface, become an esthetic and painful problem for our patients. The recessions can be treated by different surgical procedures. After a review of the etiologic factors and of the different type of wound healing, the authors describe and illustrate respectively the gingival graft for root coverage and the laterally positioned flap.

[Wound healing of a bone defect following a bone graft combined with a desmodontal tissue graft]

An experimental periodontitis was produced in the upper right and left maxillary molar regions of three dogs. The apical zone of the bony defects were marked by cutting grooves into the root surfaces. The right side was used as a control while on the left side, the bony defect was treated with a graft of ligament tissue. The graft was obtained from a neighbouring area after removing the external wall of bone and sampling with a bone chisel. Four months after the grafting the dogs were sacrificed and an optical microscopic study was performed. One of the dogs died three days after operation. In the other two dogs a reattachment was observed in the groove on the control side: coronally to the groove, a long epithelial attachment was present between the radicular wall and the connective tissue. On the experimental side of dog 1, a reattachment was obtained up to the level of the cemento-enamel junction. In dog 2, a complete failure was noted since an important epithelial growth has migrated and invaded the radicular groove.

Juvenile periodontitis: healing following autogenous iliac marrow graft, long-term evaluation

A case of juvenile periodontitis treated by autogenous bone grafting is reported. The patient, an 18-year-old female, presented with periodontal lesions around the incisors and the first lower left molar. The first molar was severely affected with bone defects at the mesial aspect and in the furcation region and, for this reason, was selected for grafting. Minced fragments of bone with its marrow, obtained from the patient's iliac crest, were implanted into the diseased periodontium. 1 year after treatment, clinical and radiological inspection revealed the presence of bone. This bone completely filled the furcation area of the tooth but only partially the mesial aspect. There was, also, significant bone fill in the supracrestal region.

Light microscopy investigation of the action of the unsaponifiable residue of vegetable oils on rat periodontal disease induced by a high carbohydrate diet

Rats, submitted to a sucrose diet for 12 months, were normally fed for another 6 months either with or without addition of the unsaponifiable residue of vegetable oils. It appears that unsaponifiable substances reinforce the collagen fiber network of the periodontium. The presence of a dense supracristal barrier accounts for the lack of an infraosseous pocket and for the limitation of bone resorption despite the high level of the sucrose diet.

A new concept regarding the origin of the junctional and crevicular epithelium in rat molars

The substitution of the internal enamel epithelium by a squamous epithelium during tooth eruption has been studied histologically in rat molars. Just prior to eruption, cytolysis of the connective tissue covering the cusp tip determines hyperplasia in the oral epithelium. A conspicuous infiltration results. Infiltrated undifferentiated cells form distinct cords which seem to be attracted by the internal enamel epithelium. They reaggregate when they come into its contact and form an underlying epithelium. The process starts in the superficial part and progressively extends towards the cervix. Finally, the internal enamel epithelium is expelled when desquamation begins. The lack of mitoses in both stratum intermedium and internal enamel epithelium and the pyknosis observed in the former, clearly show that the cells of the embryonic dental bell do not take part in the formation of the squamous epithelium as some authors still suppose.

[Histological studies of normal and pathological furcations in the rat]

In order to study the histological structure of healthy and pathological furcations in the rat, two groups of animals were submitted to two different diets: one normal and one rich in sucrose. In the first group, certain particularities were demonstrated in the periodontal ligament in the interradicular region: the fibrous network was very loose in this zone and the fibrous insertions were essentially cemento-cemental and not cemento-osseous. In the rats submitted to the high sucrose diet, a disequilibrium was noted between the apposition zones and the zones in bone and cementum resorption.

[In vitro study of the role of periosteum and the periodontal ligament in the bone repair process]

For the study of the role of periosteum and periodontal ligament in the phenomena of bone repair, fragments of palatal mucosa and maxillary or mandibular bone from adult rats and devoid of periosteum were cultivated in association. The survival went beyond 26 days. In the bone, the ligament side showed by the 12th day signs of osteogenesis, whereas the other side devoid of periosteal osteoblasts showed empty lacunea, as it is observed "in vivo".