Evaluation of a combined surgical repair and guided tissue regeneration technique to treat recent root canal perforations

This study evaluated a technique that included retrofill to repair molar root canal perforations and guided tissue regeneration to restore the periodontium that was removed from the furcation area for access to the sites. Six dogs had root canal therapy on mandibular fourth premolars and first molars. The distal root of each tooth was perforated on the furcation aspect halfway between the furcation and the apex. Replaced flap surgery was performed for access to prepare and fill the perforation site with intermediate Restorative Material. A bone xenograft was placed in the access ostectomy site and covered with GoreTex Augmentation Material (GTAM). Controls included unfilled perforations and not using bone grafts and/or GTAM. Dogs were killed at 6, 12, and 24 wk postsurgery. Complications were more common when root perforations were left unfilled. Histomorphometry revealed a statistically significant decrease in inflammation and more bone fill when root perforations were filled and GTAM was used, respectively.     

Guided tissue regeneration in Class II furcation involved maxillary molars: a controlled study of 8 split-mouth cases

The purpose of this study was to clinically evaluate the effectiveness of polytetrafluoroethylene membranes in the healing of interproximal Class II furcation defects in maxillary molars using a surgical treatment technique based on the principles of guided tissue regeneration. Eight subjects with similar bilateral Class II furcation lesions on the mesial aspect of maxillary first molars participated in this study. Patients received initial therapy consisting of oral hygiene instructions, scaling and root planing, and occlusal adjustment if necessary. Clinical parameters evaluated included plaque index, sulcular bleeding index, probing depth, attachment level, gingival recession, and open horizontal and vertical furcation fill. An acrylic occlusal stent was used to assure reproducibility of measurements. Experimental sites received a polytetrafluoroethylene membrane following surgical exposure of the furcation. Control sites were treated in the exact same manner but without a membrane. Membranes were removed at 6 weeks after the first surgery. Reentry surgeries were performed at 9 months. Postsurgical results showed a significant improvement in probing depth, attachment level, and open horizontal furcation fill for both groups when compared to baseline values, with experimental sites performing significantly better than controls. Control sites showed a slight loss in open vertical furcation fill while experimental sites remained unchanged. This study suggests that guided tissue regeneration using polytetrafluoroethylene membranes is of some but limited value in the treatment of maxillary molar interpoximal Class II furcation lesions.     

The study of molar furcation involvements in adult periodontitis. II. Age, sex, location and prevalence

The purposes of the study were as follows: (1) to evaluate the molar furcation involvement and number of molar correlated with age and sex; and (2) to study the relationship between the means of alveolar bone loss and associated factors of molar furcation involvements (FIs). 1102 molars (703 males and 399 females) were measured in 219 individuals (136 males and 83 females) for the alveolar bone loss and associated factors of molar furcation involvements. Based on the results, we conclude the following: (1) the higher prevalence of FI was in the mandibular first molar (94.6%), whereas the lowest prevalence of FI was in maxillary second molar; (2) except for the mandibular first molar, the prevalence of molar FI markedly increased with an increased age group (16 & 26, r = 0.335, p < 0.01; 17 & 27, r = 0.345, p < 0.01; 37 & 47, r = 0.239, p < 0.01); (3) the prevalence of molar FI was significantly higher in males than in females (p < 0.05); (4) the mean number of molar FI was significant greater in males (mean = 3.45) than in females (mean = 2.69); (5) factors such as age (r = 0.222, p < 0.01), sex, (r = 0.145, p < 0.05), number of remaining teeth (r = -0.330, p < 0.01) and molar FI (r = 0.471, p < 0.01) are strongly associated with the mean alveolar bone loss of molars.     

Preimplant guided bone regeneration in the anterior maxilla

Guided bone regeneration is a clinical procedure aimed at promoting bone formation at sites where there is severe bone loss. The purpose of this article was to demonstrate reconstruction of deformations of the alveolar process resulting from traumatic injuries to maxillary incisor teeth by guided bone regeneration procedures followed by insertion of dental implants. In both cases, submembranous space-making was stabilized by human demineralized freeze-dried bone. Implant insertion at the sites of bone augmentation resulted in successful restorations. Histologic examination of biopsy samples from the submembranous hard tissue revealed particles of demineralized freeze-dried bone allografts partially surrounded by uninflamed connective tissue and by vital bone adjacent and adhered to the demineralized freeze-dried bone allograft particles.     

The effect of transforming growth factor beta one (TGF-beta 1) on wound healing, with or without barrier membranes, in a Class II furcation defect in sheep

The purpose of this study was to analyse the effect of TFG-beta 1 on wound healing in standardized Class II furcation defects of 48 mandibular second premolar teeth in 24 sheep. The experimental design included a control group (carrier only, 25% pluronic F-127), and 2 experimental groups: group A (80 micrograms/ml TGF-beta 1 + carrier) and group B (80 micrograms/ml TGF-beta 1 + carrier covered with a barrier membrane). Sheep were killed either 2 wk or 6 wk after surgery. Mesiodistal sections of the decalcified specimens were quantified histologically using stereology. Percentage volumes of regenerated bone, fibrous connective tissue and cementum were calculated for each furcation defect. Mean values were analysed using multiple ANOVA; p values were calculated using paired and unpaired Student's t-tests. After 2 wk there was more bone in group B than either of the other 2 groups, but this was not statistically significant. By 6 wk more bone was present in group A than in the control group (p < 0.02) and also in group B when compared with both group A and the control group (p < 0.02 and p < 0.44), respectively. In the 4 wk between sampling significantly more bone had formed (group A < 0.05 and group B p < 0.003, respectively). A negative correlation existed between volumes of bone and fibrous connective tissue and no significant differences between the volumes of cementum were evident between any of the groups. This study demonstrated that TGF-beta 1 encouraged bone regeneration in Class II furcation defects in sheep, an effect enhanced by the presence of a barrier membrane. This is the first report on the use of TGF-beta 1 in conjunction with GTR in periodontal defects.     

Effect of allogeneic, freeze-dried, demineralized bone matrix on guided bone regeneration in supra-alveolar peri-implant defects in dogs

This randomized, split-mouth design study evaluated the adjunctive effect of allogeneic, freeze-dried, demineralized bone matrix on guided bone regeneration in a critical-size, supra-alveolar, peri-implant defect model. Contralateral supra-alveolar peri-implant defects, 5 mm in height, each including two titanium implants, were surgically created in five beagle dogs. Demineralized bone matrix in autologous blood was placed over the implants in one randomly selected mandibular jaw quadrant. A space-making expanded-polytetrafluoroethylene membrane was used to provide guided bone regeneration bilaterally. Following a 16-week healing interval, tissue blocks were harvested and prepared for histometric analysis. Differences between experimental conditions (guided bone regeneration sites with and without demineralized bone) were evaluated using paired t tests (n = 4). Demineralized bone particles were discernible, with limited signs of resorption. The bone matrix particles appeared to be solidified within a dense connective tissue matrix and in close contact with the implants. Limited matrix remineralization was apparent adjacent to the alveolar crest. No statistically significant differences were found between experimental conditions for any parameter examined. Peri-implant defect height averaged 5.0 +/- 0.2 mm and 4.9 +/- 0.4 mm, vertical bone regeneration 1.5 +/- 0.9 mm and 1.1 +/- 0.4 mm, osseointegration within the extent of the defect 10.0 +/- 3.9% and 15.3 +/- 5.3%, osseointegration within the extent of regenerated bone 30.4 +/- 13.7% and 52.1 +/- 17.9%, and osseointegration within the alveolar base 68.8 +/- 13.1% and 74.4 +/- 7.1% for guided bone sites with and without demineralized bone, respectively (P > .05). The results suggest that freeze-dried demineralized bone has no adjunctive effect on guided bone regeneration in supra-alveolar peri-implant defects, that guided bone regeneration has a limited potential to enhance alveolar regeneration in this defect model, and that a 16-week healing interval appears insufficient for turnover and maturation of demineralized bone under provisions for guided bone regeneration.     

Evaluation of periosteal membranes and coronally positioned flaps in the treatment of Class II furcation defects: a comparative clinical study in humans

The purpose of this study was to compare the clinical effectiveness of connective tissue grafts including periosteum used as a mechanical barrier for guided periodontal tissue regeneration and coronally positioned flaps in the treatment of Class II furcation defects. A total of 28 furcation defects were treated; 14 received a periosteal barrier and 14 received a coronally positioned flap. Reentry surgeries were performed at 6 months. No statistically significant differences were found preoperatively between the two treatment groups with respect to clinical parameters and osseous measurements. Postsurgically, both treatment modalities resulted in a significant decrease in probing depth and a significant gain in clinical attachment, but the differences observed were not statistically significant. The periosteal barrier group presented with a significantly better gain in vertical components of the alveolar bone (1.93 +/- 0.15 mm and 0.20 +/- 0.26 mm for periosteal barrier and coronally positioned flap groups, respectively; P < or = 0.001) and horizontal components of the alveolar bone (1.60 +/- 0.21 mm and 0.13 +/- 0.90 mm for periosteal barrier and coronally positioned flap groups, respectively; P < or = 0.001). The results of this trial indicate that similar clinical resolution of Class II furcation defects can be obtained with periosteal barriers and coronally positioned flaps. Periosteal barriers, however, are a better treatment alternative in achieving bone fill of the furcation area.     

Evaluation of a high-density polytetrafluoroethylene (n-PTFE) membrane as a barrier material to facilitate guided bone regeneration in the rat mandible

The purpose of this investigation was to evaluate the use of high-density polytetrafluorethylene (n-PTFE) membranes to facilitate guided tissue regeneration (GTR) in the rat. The concept of guided tissue regeneration is based on the hypothesis that if the non-osteogenic connective tissue cells are mechanically blocked from entering a bone defect, selective re-population of the defect by osteoblasts will occur. Bilateral through-and-through defects of critical size were created in the mandibular angle of 12 rats. The experimental side was covered on both the medial and lateral aspects of the mandible with high-density n-PTFE membrane, with the opposite side serving as a control. Histological analysis revealed osteogenic tissue completely bridging the defect by two weeks. After six weeks of healing, osteogenic repair was observed at the margins of the defects, with islands of woven bone seen in the central areas. After 10 weeks of healing, complete ossification was observed on the n-PTFE-treated side. The control defects exhibited very little osseous regeneration, and rounding of the defect margins was observed after 10 weeks of healing. These results indicate that high-density n-PTFE can serve effectively as a guided tissue regeneration barrier in certain bone defects.     

Treatment of peri-implantitis using guided bone regeneration and bone grafts, alone or in combination, in beagle dogs. Part 1: Clinical findings and histologic observations

The purpose of this study was to evaluate and compare the treatment of ligature-induced peri-implantitis using guided bone regeneration and two bone grafts alone and in combination. Mandibular premolars and first molars were extracted from four beagle dogs and after 3 months of healing, three Br?nemark implants were placed on each side of the mandibles. Following abutment connection 3 months later, experimental peri-implantitis was induced by tying plaque-retentive ligatures around all abutments. Ligatures and abutments were removed after 3 months, and bony defects measured and treated with either: (1) debridement only; (2) debridement plus resorbable hydroxyapatite; (3) debridement plus canine freeze-dried demineralized bone; (4) debridement plus guided bone regeneration; (5) debridement plus resorbable hydroxyapatite and guided bone regeneration; or (6) debridement plus canine freeze-dried demineralized bone and guided bone regeneration. Pretreatment and 4-month-posttreatment comparison revealed a significant but variable degree of clinically appreciable hard tissue fill with all treatment procedures. Guided bone regeneration procedures resulted in the greatest fill, followed by bone grafts alone and flap debridement. There was no significant difference between guided bone regeneration and both guided bone regeneration/graft combinations; therefore, guided bone regeneration procedures appear to be a predictable treatment for plaque-induced peri-implant defects.     

Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model

The purpose of this study was to evaluate the ability of mineral trioxide aggregate (MTA) and amalgam to seal furcal perforations in extracted human molars using an anaerobic bacterial leakage model. Furcal perforations were made in 39 maxillary and mandibular human molars with a high-speed bur. These were randomly divided into two experimental groups of 18, with the remaining three teeth used as positive controls. Experimental group 1 was repaired with MTA and group 2 with amalgam. Three additional teeth without perforations served as negative controls. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion broth with yeast extract, hemin, menadione, and the chromogenic indicator bromcresol purple was used as the culture broth for Fusobacterium nucleatum. Eight of 18 amalgam samples leaked, whereas none of the 18 MTA samples leaked. MTA was significantly better than amalgam in preventing leakage of F. nucleatum past furcal perforation repairs.     

Evaluation of setting properties and retention characteristics of mineral trioxide aggregate when used as a furcation perforation repair material

Furcation perforations were created in 32 extracted maxillary and mandibular molars. The perforations were prepared in the center of the pulp chamber floor parallel to the long axis of each tooth and a saline-moistened Gelfoam matrix was placed below the perforation to simulate a clinical condition. The teeth were randomly divided into four groups, and the perforations were all repaired with mineral trioxide aggregate (MTA) and then covered with either a wet or dry cotton pellet for 24 or 72 h. Instron testing was used to measure the force required to displace the material from the perforation. The force measurements showed that MTA resisted displacement at 72 h to a significantly greater level than at 24 h (p < 0.05). When slight displacement occurred at 24 h the material demonstrated the ability to re-establish resistance to dislodgement from the dentin wall. The presence of some moisture in the perforation during placement was advantageous in aiding adaptation of MTA to the walls of the perforation, but there was no significant difference in MTA retention when a wet or dry cotton pellet was placed in the pulp chamber during the setting time (p > 0.05).     

Gingival recession and exposure of barrier membrane: effect on guided tissue regeneration of Class II furcation defects

The purpose of the present study was to evaluate the effect of barrier membrane exposure on the success of guided tissue regeneration in Class II furcation defects. Twenty-six subjects with mandibular Class II furcation defects received initial periodontal therapy followed by guided tissue regeneration surgery. The membrane was placed and the flaps were repositioned so that the membrane was totally submerged. Membranes were removed 4 to 6 weeks later, at which time the extent of their exposure was recorded. An overall improvement in all clinical parameters was observed for all subjects 1 year after surgery. Half of the patients had experienced no membrane exposure, while the other 13 subjects had experienced mild to pronounced exposure; both groups showed similar improvement in all clinical and surgical parameters. In light of the comparable results obtained in exposed sites, and the anatomic difficulties sometimes encountered in covering a membrane completely, in some of these cases the membrane may be left only partially submerged. This approach will allow for tighter occlusal "seal" of the tooth-membrane interface and preservation of the keratinized gingiva.     

Endodontic applications of guided tissue regeneration in endodontic surgery

This paper is intended to provide an overview of different endodontic applications in guided tissue regeneration. It is our expectation that using these techniques, where applicable, will increase endodontic surgical success. We have described six different clinical conditions including external resorption, root perforation, dehiscence, palatal grooves, oblique root fractures, and large periapical lesions. We believe the use of guided tissue regeneration techniques will allow us to predictably treat teeth that otherwise might be extracted.     

Cholinergic mechanism and blood pressure regulation in the central nervous system

This study evaluated alveolar bone and cementum regeneration following surgical implantation of recombinant human transforming growth factor-beta1 (rhTGF-beta1) in conjunction with guided tissue regeneration (GTR). Supraalveolar, critical size, periodontal defects were surgically created around the 3rd and 4th mandibular premolar teeth in right and left jaw quadrants in 5 beagle dogs. Alternate jaw quadrants in consecutive animals received rhTGF-beta1, in a CaCO3/hydroxyethyl starch carrier with GTR, or carrier with GTR alone (control). 20 microg of rhTGF-beta1 in buffer solution was incorporated into approximately 0.8 ml of carrier for each defect scheduled to receive rhTGF-beta1. Animals were sacrificed at week 4 postsurgery and tissue blocks were harvested and processed for histometric analysis. Clinical healing was generally uneventful. Minor membrane exposures were observed. Defects with membrane exposure displayed an inflammatory infiltrate underneath the membrane. Bone regeneration of trabecular nature, apparent in all animals, was generally limited to the very apical aspect of the defects. Cementum regeneration was limited without obvious differences between experimental conditions. Comparing rhTGF-beta1, to control defects, statistically significant differences were found for area (1.8+/-0.4 and 1.3+/-0.6 mm2, respectively; p<0.05) and density (0.3+/-0.1 and 0.2+/-0.03, respectively; p<0.05) of alveolar bone regeneration. Observed differences are small and represent a clinically insignificant potential for enhanced regeneration in this preclinical model. Within the limitations of study, it may be concluded that rhTGF-beta1 has a restricted potential to enhance alveolar bone regeneration in conjunction with GTR.     

Secular trends in proximal femoral fracture, Oxford record linkage study area and England 1968-86

OBJECTIVES: Bone defects are a challenge for the dental clinician. As widely accepted in guided tissue regeneration, physically halting soft connective tissue proliferation into bone allows for bone regeneration. This concept is the "osteopromotion principle." The aim of this study was to assess the osteopromoting effect of calcium sulfate as a barrier. STUDY DESIGN: Forty male Sprague-Dawley rats were used. Mucoperiosteal flaps were raised bilaterally at buccal and lingual aspects of the mandible to expose the angles. Next, 5 mm through-and-through bony defects were created bilaterally. On the test side, sterile medical grade prehardened calcium sulfate disks were applied both lingually and buccally to cover the defect. The control side defects were left uncovered. All flaps were sutured closed. Observation times were 3, 9, 18, and 22 weeks. RESULTS: Histologic analysis demonstrated that at 3 weeks all test sites showed partial or complete bone healing. Similar findings were reported for all observation times. The control group showed no bone growth at 3 and 9 weeks and partial bone healing at 18 and 22 weeks. CONCLUSIONS: This study indicates that calcium sulfate barriers can exclude connective tissues, allowing bone regeneration during healing.     

Parental awareness of dental caries in toddlers

Endodontic endosseous implants stabilize teeth that have crown-root ratios compromised by periodontal disease, trauma, or apical resorption. By increasing the crown-root ratio, the implant improves the prognosis of the tooth, thus increasing its longevity. The purpose of this study was to evaluate, in vivo, the healing response to a newly introduced titanium endodontic implant. Eight implants were placed in the maxillary incisors and mandibular premolars of two adult beagle dogs after completion of root canal and osseous preparation. Peri-implant tissues were examined radiographically and histologically at 6 months postinsertion. Radiographically, the periapical area and tissue surrounding the implants seemed normal. Histologically, fibrous connective tissue and healthy bone intimately surrounded the implant. Epithelium or chronic inflammatory cells were not observed along the length of the implant. These findings suggest that titanium is a biocompatible metal when used as an endodontic endosseous implant.     

Clinical and histologic observation of replacement of biphasic calcium phosphate by bone tissue in monkeys

Biphasic calcium phosphate, consisting of beta-tricalcium phosphate and hydroxyapatite, was implanted in wide and deep periodontal osseous defects of monkeys in combination with the guided tissue regeneration technique. After 12 weeks, sites treated with a combination of biphasic calcium phosphate and guided tissue regeneration maintained the shape of the ridge, but both guided tissue regeneration and control sites (untreated) showed extreme resorption. A histopathologic investigation revealed that numerous macrophages contained small particles of ceramic within their vesicles and the active bone replacement occurred from the surrounding bone. Biphasic calcium phosphate has osteoconductive potential and this potential may be related to degradation by macrophage phagocytosis.     

Comparative in vitro effectiveness of closed root debridement with fine instruments on specific areas of mandibular first molar furcations. I. Root trunk and furcation entrance

The purpose of this study was to compare curets with a small blade to slim ultrasonic inserts on their efficacy in removing artificial deposits from the root trunk and furcation entrance areas of mandibular molars using an in vitro model simulating a clinically closed root debridement approach. The study was conducted on 100 artificial mandibular first molars (50 right side and 50 left side) with anatomical roots. Root trunks, furcation entrances, and furcation areas of each molar were colored by a coat of black model paint. The teeth were fixed in a custom acrylic model and maintained in a firm position by modified acrylic occlusal splints. The root areas were covered with a heavy rubber dam imitating gingival tissue. The model was attached to a mannequin and mounted on a dental chair. Fifty molars (25 right, 25 left) were instrumented with the experimental curets and an equivalent number of molars with the ultrasonic inserts. The instrumentation was carried out by one experienced operator, spending 4 minutes on each molar. The instrumented areas were individually analyzed to determine the percentage of deposits remaining, using a computerized imaging routine system. One-way analysis of variance was conducted to test for differences between both types of instruments. Results revealed that the curets were significantly more efficient (P < 0.01) than the ultrasonic inserts in removing paint from both root trunks and furcation entrances. These findings should be corroborated in a clinical study to determine the potential value of the instruments tested during initial therapy or supportive care of involved mandibular furcations.     

The clinical, angiographic and procedural predictors of thrombosis and restenosis in Micro stent II (AVE) coronary stents]

In the present study, the potential of a diphenylphosphorylazide-crosslinked type I bovine collagen membrane was evaluated in the healing of mandibular bone defects applying the biological concept of guided bone regeneration. The experiment was carried out on 25 Wistar rats. After exposing the mandibular ramus bilaterally, 5 mm diameter full-thickness circular bone defects were surgically created. While the defect on one side was covered by the membrane (experimental), the defect on the other side was left uncovered (control) before closure of the overlying soft tissues. The rats were sacrificed in groups of 5 after 7, 15, 30, 90, and 180 days of healing. Although at early stages of healing similar amounts of bone formation were observed in the experimental and control defects, after 1 month of healing, most of the experimental defects were completely closed with new bone, while in the control defects, only limited amounts of new bone were observed at the rims and in the lingual aspect of the lesions. In the 90- and 180-day animals, all experimental defects were completely closed, while in the control defects, no statistically significant increase in bone regeneration was observed. The increase in percentage of bone regeneration in the experimental defects was statistically significant between the 15-day specimens as compared with the 7-day specimens (P < 0.01) and likewise between 30-day and 15-day specimens (P < 0.001). It can be concluded that a DPPA-crosslinked collagen membrane yields biocompatibility, ad hoc mechanical hindrance, and handling characteristics suitable for guided bone regeneration applications in this experimental model.     

Preservation of alveolar bone in extraction sockets using bioabsorbable membranes

The purpose of this study was to evaluate the clinical effectiveness of a bioabsorbable membrane made of glycolide and lactide polymers in preserving alveolar ridges following tooth extraction using a surgical technique based on the principles of guided bone regeneration. Sixteen patients requiring extractions of 2 anterior teeth or bicuspids participated in the study (split-mouth design). Following elevation of buccal and lingual full-thickness flaps and extraction of teeth, experimental sites were covered with bioabsorbable membranes; control sites did not receive any membrane. Titanium pins served as fixed reference points for measurements. Flaps were advanced in order to achieve primary closure of the surgical wound. No membrane became exposed in the course of healing. Reentry surgeries were performed at 6 months. Results showed that experimental sites presented with significantly less loss of alveolar bone height, more internal socket bone fill, and less horizontal resorption of the alveolar bone ridge. This study suggests that treatment of extraction sockets with membranes made of glycolide and lactide polymers is valuable in preserving alveolar bone in extraction sockets and preventing alveolar ridge defects.