Periodontal repair in dogs: effect of root surface treatment with stannous fluoride or citric acid on root resorption

This study evaluated healing, with emphasis on root resorption, following root surface treatment with 1% aqueous stannous fluoride (SnF2), saturated citric acid (CA), or saline control (C) in conjunction with periodontal flap surgery. Supraalveolar periodontal defects were surgically created and immediately treated in the mandibular premolars in 6 beagle dogs. The defect height approximated 5 to 6 mm from the reduced alveolar bone to the cemento-enamel junction. Root treatments were rotated between experimental teeth within jaw quadrants and duplicated in left and right quadrants in the dogs. Flaps were raised to cover most of the crowns of the teeth and sutured. The dogs were sacrificed 12 weeks after surgery and tissue blocks with teeth and adjacent structures were processed for histometric analysis. SnF2-treated teeth healed with significantly longer junctional epithelium, less connective tissue repair to the root surface, and less bone regeneration than CA and C-treated teeth. New cementum formation was limited in all treatment groups. Root resorption was observed in almost all teeth exhibiting connective tissue repair, however to a lesser amount and not as frequent in SnF2 treated teeth due to limited connective tissue repair. No differences were found in amount and frequency of root resorption in CA and C-treated teeth. An inhibitory effect on root resorption of SnF2 could not be disclosed in this experiment, however, it may be concluded that CA treatment of the root surface in conjunction with reconstructive periodontal flap surgery does not seem to enhance root resorption.     

Periodontal repair in dogs: healing in experimentally created chronic periodontal defects

A need exists for well-defined animal models to objectively evaluate surgical principles and a possible role for biochemical wound conditioning and biomaterials in promoting periodontal regeneration. To test an existing model for its usefulness in quantitative evaluation of periodontal wound healing, large supraalveolar periodontal defects were surgically created around the mandibular premolars (P2, P3, P4) in left or right jaw quadrants in 5 beagle dogs. The defects were exposed to the oral environment for 6 months and were then subjected to reconstructive flap surgery (chronic defects). Healing in these defects was compared to healing following reconstructive surgery in similar contralateral defects which had not been exposed to plaque and calculus (acute defects). The animals were sacrificed after a 4-week healing period and tissue blocks including teeth and surrounding structures were processed for histometric analysis. Mean defect height (+/- s.d.) for chronic and acute defects amounted to 4.6 +/- 0.3 and 4.4 +/- 0.4 mm, respectively. Mean connective tissue repair to the root surface in chronic defects amounted to 62% (range 49% to 74%) of the defect height. Mean connective tissue repair in the acute defects exceeded 94% of the defect height in 4 of the dogs, but amounted to only 48% in 1 dog. Regeneration of alveolar bone and cementum was limited under both experimental conditions. Root resorption was frequently encountered, whereas ankylosis was seen in only few teeth. This study indicates that healing may vary not only as a result of controlled experimental variables, but also due to differences in biological response between dogs or to fortuitous traumatic factors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Repair of periodontal furcation defects in beagle dogs following reconstructive surgery including root surface demineralization with tetracycline hydrochloride and topical fibronectin application

This study examines the effects of root surface demineralization and topical fibronectin as adjuncts to reconstructive periodontal surgery. In 14 beagle dogs, horizontal periodontal defects were surgically induced around the mandibular premolars followed by a 6-week period without plaque control. Reconstructive surgery of the defects was subsequently carried out. The root surfaces were debrided and superficially demineralized with citric acid or tetracycline hydrochloride, with or without subsequent application of fibronectin. Mucoperiosteal flaps were raised to cover most of the crowns and sutured. The animals were sacrificed 12 weeks after surgery and block sections of the teeth and surrounding tissues were processed for histology. Analysis included incidence of furcation defects presenting with an epithelial lining, quantification of connective tissue repair relative to the furcation circumference, and regeneration of alveolar bone relative to the furcation defect height. The incidence of root resorption and ankylosis was also analyzed. Within the limitations of this study it was concluded that: (1) citric acid conditioning of the root surface frequently resulted in complete connective tissue repair of the furcation defect; (2) root resorption and ankylosis were prevalent features of the healing response; (3) citric acid and tetracycline treatment had similar potential to induce connective tissue repair and resulted in corresponding incidences of root resorption and ankylosis; (4) application of fibronectin to demineralized root surfaces did not enhance the amount of connective tissue repair and did not alter the pattern of root resorption and ankylosis.     

骨形成蛋白促进牙周组织再生的动物实验研究

目的将骨形成蛋白（ｂｏｎｅｍｏｒｐｈｏｇｅｎｅｔｉｃｐｒｏｔｅｉｎ，ＢＭＰ）联合应用于牙周引导组织再生（ｇｕｉｄｅｄｔｉｓｓｕｅｒｅｇｅｎｅｒａｔｉｏｎ，ＧＴＲ）技术中，观察和比较其对牙周组织再生修复的影响和意义。方法制备狗下颌后牙区人工骨缺损，于清创后分组置入引导膜材料和ＢＭＰ，以常规翻瓣术为对照；分不同时期取材做组织学观察和评价。结果实验组较对照组新生组织量多，而以复合ＢＭＰ组效果最为显著；膜材料在早期有一定抑制结合上皮根向迁移的作用。结论利用外源性ＢＭＰ的主动生物诱导活性，可望应用于临床促进牙周硬组织成分的新生修复。     

Effect of recombinant human bone morphogenetic protein-2/absorbable collagen sponge (rhBMP-2/ACS) on healing in 3-wall intrabony defects in dogs

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier is being evaluated as a candidate therapy for periodontal regeneration. The objective of this study was to evaluate regeneration of alveolar bone and cementum, and associated root resorption and ankylosis following surgical implantation of rhBMP-2/ACS in a canine clinical model. METHODS: Bilateral 3-wall intrabony periodontal defects were surgically induced in the premolar region in the maxilla and mandible in 8 young adult Korean mongrel dogs. The defects in each animal received rhBMP-2/ACS (rhBMP-2 at 0.2 mg/ml, total implant volume/defect approximately 0.1 ml) or buffer/ACS, or served as sham-operated controls. Surgeries were sequenced for each animal to provide postmortem observations following 8- and 24-week healing intervals. Treatment outcomes were evaluated using clinical, radiographic, and histometric parameters. RESULTS: Surgical implantation of rhBMP-2/ACS resulted in accelerated enhanced bone formation in the 3-wall intrabony periodontal defects but in no apparent enhancement of cementum regeneration. rhBMP-2/ACS did not appear to be associated with aberrant healing events such as root resorption and ankylosis under these simulated clinical conditions. CONCLUSIONS: Surgical implantation of rhBMP-2/ACS may be used safely to support regeneration of alveolar bone in intrabony periodontal defects in dogs without aberrant events such as root resorption or ankylosis complicating the regenerative procedure. rhBMP-2/ACS does not appear to have a significant effect on cementum regeneration and formation of a functional periodontal ligament in this model.     

Engineered autologous bone marrow mesenchymal stem cells: alternative to cleft alveolar bone graft surgery

ABSTRACT: Human recombinant bone morphogenetic protein 2 (rhBMP-2) accelerates bone regeneration but is associated with limited cementum and periodontal ligament regeneration, local root resorption, and ankylosis. This study assessed a new approach to the regeneration of the alveolar bone and periodontal attachment apparatus using a combination of ex vivo autologous bone marrow mesenchymal stem cells (MSCs) engineered by replication defective adenovirus to express the BMP-2 gene and pluronic F127 (PF127) in a large mammalian animal model. Bilateral maxillary periodontal defects were created over the premolar area in 9 mature male miniature swine. The 18 defects were randomly assigned to receive either BMP-2-expressing MSCs in the advBMP-2 group or MSCs alone in the MSC group. The regenerated periodontal attachment apparatus was evaluated histologically, and the total regenerated bone volume was calculated from three-dimensional computed tomography analysis. Three months after implantation, significant bone volume was regenerated in the advBMP-2 group. Periodontal apparatus regeneration was significantly better in the advBMP-2 group. New cementum and Sharpey fibers were observed on the denuded root surfaces in the advBMP-2 group, whereas incomplete healing with localized root surface resorption was noted in the control group. The use of ex vivo BMP-2-engineered autologous MSCs enhanced bone and periodontal apparatus regeneration in maxillary alveolar and periodontal defects in swine. This novel integrated approach might be suitable for clinical periodontal apparatus repair. This may be an alternative for cleft alveolar bone graft surgery.     

Histologic evaluation of new attachment apparatus formation in humans. Part III

There is still controversy as to the role of bone grafting materials in the formation of a new attachment apparatus and component tissues (bone, cementum, and periodontal ligament). The purpose of this study was to compare the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a nonsubmerged environment in humans. The most apical level of calculus on the root served as a histologic reference point to delineate root surfaces exposed to the oral environment and to measure new attachment apparatus and new component tissue formation. Free gingival grafts were placed over grafted and nongrafted defects to retard epithelial migration. Biopsies were obtained at 6 months and regeneration was evaluated histometrically. Data from 12 patients with 32 grafted and 25 nongrafted defects were submitted for statistical analysis. Results indicate that in nongrafted defects, a long junctional epithelium formed along the entire length of exposed root surfaces and often extended apical to the calculus reference notch. Free gingival grafts did not enhance regeneration of a new attachment apparatus, new cementum, new connective tissue, or new bone in nongrafted defects. The formation of a new attachment apparatus was observed when intrabony defects were grafted with DFDBA (x1.21 mm); significantly more new attachment apparatus (P less than .005), new cementum (P less than .005), new connective tissue (P less than .05), and new bone (P less than .0001) formed in intrabony defects grafted with DFDBA than in nongrafted defects. There was a greater chance for regeneration of a new attachment apparatus and component tissues in grafted defects than in nongrafted defects. New cellular cementum formed on old cementum and dentin but more often formed over both in the same defect). The periodontal ligament was more frequently oriented perpendicular to the root; there was greater loss in alveolar crest height in nongrafted than grafted defects (P less than .05); and extensive root resorption, ankylosis, and pulp death were not observed in grafted or nongrafted defects.     

Histologic evaluation of new attachment apparatus formation in humans. Part II

There is conflicting evidence regarding the value of graft materials in enhancing the formation of new bone, cementum, and periodontal ligament (new attachment apparatus). Part II of this study compared the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a submerged environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Biopsies were obtained at 6-months and evaluated histometrically by two investigators unaware of the treatment performed. Data from 9 patients with 30 grafted defects and 13 nongrafted defects were submitted for statistical analysis. Results indicate that in a submerged environment significantly more new attachment apparatus (P less than .05) and new bone (P less than .05) formed in grafted than nongrafted sites. Significantly greater loss of alveolar crest height occurred in nongrafted than grafted defects (P less than .05); regeneration of new attachment apparatus, new bone, and new cementum occurred more frequently in grafted than nongrafted defects. There was a greater chance for the regeneration of a connective tissue attachment in nongrafted intrabony defects than in grafted defects; new cellular cementum formed equally well on old cementum, dentin, or both old cementum and dentin in the same defect. The periodontal ligament was oriented parallel, perpendicular, or both parallel and perpendicular in the same defect; and, no extensive root resorption, ankylosis, or pulp death was observed in grafted or nongrafted defects.     

Periodontal repair in dogs: histologic observations of guided tissue regeneration with a prostaglandin E1 analog/methacrylate composite

This report describes observations of healing following guided tissue regeneration (GTR) including surgical implantation of the prostaglandin E1 analog misoprostol with calcium-layered methacrylate particles. Critical size, supra-alveolar periodontal defects were surgically created around the 3rd and 4th mandibular premolar teeth in 4 beagle dogs. Wound management included soaking with a 24 microg/ml misoprostol solution and implantation of the misoprostol/methacrylate composite. One jaw quadrant per animal was prepared for GTR using expanded polytetrafluoroethylene membranes. The gingival flaps were coronally advanced and sutured to submerge the teeth. The tissues covering the surgical sites daily received topical misoprostol in an oral adhesive over the 4-week healing interval. Upon euthanasia, tissue blocks were prepared for histometric analysis of regeneration of alveolar bone and cementum, root resorption and ankylosis. The defect area underneath the membrane and the density of methacrylate particles were recorded for the GTR defects. The methacrylate particles appeared encapsulated in a dense connective tissue without signs of an inflammatory reaction, some in contact to newly formed bone. Alveolar bone regeneration height averaged (+/-SD) 1.2+/-1.0 and 1.0+/-0.6 mm for GTR and non-GTR defects, respectively. Corresponding values for bone regeneration area were 1.3+/-1.0 and 0.7+/-0.5 mm2. Cementum regeneration was confined to the apical aspect of the defects. Small areas of root resorption and ankylosis were observed for all teeth. Bone regeneration area correlated positively to the defect area and negatively to the density of methacrylate particles in the GTR defects. The histologic observations suggest that the methacrylate composite has marginal potential to promote bone and cementum regeneration under provisions for GTR.     

Experimental study of periodontal tissue regeneration. Changes in the periodontium after tooth implantation with and without periodontal ligament

The role of the periodontal ligament in periodontal tissue regeneration was evaluated. The materials included bilateral upper 1st premolars and lower 2nd, 3rd, and 4th premolars of 11 adult Beagle dogs, aged from 3 to 6 years. Before implantation, the right teeth were extracted and kept for a period of more than 3 months in "a solution for reserving teeth". The left teeth on the other hand, were extracted and soon implanted thus retaining the periodontal ligament into the newly created bone cavities prepared in the right edentulous areas. At the same time, the right reserved teeth were implanted into the left tooth sockets. Implanted teeth were periodically observed macroscopically, radiographically, and histologically for a 6-month period. Macroscopical observation showed good clinical repair in the bilateral sides of the tooth implantation with and without a periodontal ligament. After a 6-week experimental period, radiographic observations of the implanted lower right teeth having a periodontal ligament revealed lamina dura-like findings. Histopathological investigation revealed ankylosis and root resorption on the left side, where the reserved teeth without a periodontal ligament were implanted. But regeneration of the periodontal tissue complex, which consisted of the gingiva, alveolar bone, cementum, and periodontal ligament, was generally observed in the implanted right teeth having a periodontal ligament. These results suggest that the periodontal ligament cells play a significant role in periodontal tissue regeneration.     

Periodontal regeneration of transplanted rat molars after cryopreservation

The effects of cryopreservation on periodontal regeneration of transplanted rat molars were investigated histologically and histochemically in rats. Bilateral first and second maxillary molars of 4-week-old Wistar rats were gently extracted and transplanted into the abdominal subcutaneous connective tissue immediately or after cryopreservation in liquid nitrogen overnight. Donor teeth were slowly frozen by a rate-controlling freezer (program freezer) using 5% dimethylsulfoxide (DMSO) and 6% hydroxyethyl starch (HES) as cryoprotectants. One-four weeks after transplantation, they were carefully excised with the surrounding tissues. Regeneration of acellular cementum, periodontal ligament, and alveolar bone were observed 2 weeks after immediate transplantation. The pulp was repaired by the ingrowth of granulation tissue from the root apex followed by the formation of calcified tissue. The regenerated periodontal ligament was positive for alkaline phosphatase (ALP). Small or mononuclear tartrate resistant acid phosphatase (TRAP) positive cells were scattered on the newly formed alveolar bone and on the hard tissue in the pulp, but there was no external or internal progressive root resorption at 4 weeks. Cryopreserved teeth had acellular cementum with a rough surface at 1 week, but with the increase of cementoblasts and the appearance of periodontal ligament and alveolar bone, the surface became smooth at 3 weeks. Epithelial rests of Malassez (ERM) also revived. After regeneration of the periodontal tissues at 4 weeks, there was no evidence of root resorption. Although the process proceeded slowly, the cryopreserved teeth showed the periodontal regeneration substantially similar to that of the immediately transplanted teeth without progressive root resorption, indicating that they could be applicable for clinical use.     

Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man

This study was designed to investigate human repair and reattachment of principal periodontal fibers in areas of resorption on anchor premolar root surfaces following rapid maxillary expansion. Maxillary first premolar teeth were obtained from patients requiring rapid maxillary expansion. Extraction of the teeth was scheduled after periods of retention varying between 14 and 53 weeks. The roots of the teeth were examined via light microscopy and scanning electron microscopy. Extensive root resorption characterized the buccal surfaces of anchor premolars. Repair of the resorptive defects was found to occur exclusively with cellular cementum. Anchor teeth retained for longer periods, up to the maximum of 53 weeks of retention in this study, generally demonstrated more advanced repair. Topographically, Sharpey fiber holes indicative of principal periodontal fiber insertion were found in repair cementum. However, these depressions were neither numerous nor consistent in their presence and location. In human teeth, periodontal attachment to resorbed and repairing surfaces was shown to be present. SEM studies of histologic sections revealed that periodontal fibers and fiber bundles inserted directly into the repair cellular cementum matrix, irrespective of the site of the lesion on the root.     

Favorable periodontal healing of 1-wall infrabony defects after application of calcium phosphate cement wall alone or in combination with enamel matrix derivative: a pilot study with canine mandibles

BACKGROUND: Although various periodontal regenerative therapies are used, their effects on non-contained infrabony defects are unpredictable. Our previous studies showed that injectable, moldable, fast-setting calcium phosphate cement (CPC) promoted histocompatible periodontal healing in 3-wall intrabony defects. The present study evaluated healing patterns after surgical application of CPC walls with and without an enamel matrix derivative (EMD) in 1-wall infrabony defects in dogs. METHODS: One-wall infrabony defects (5 x 5 x 4 mm) were created surgically on the mesial and distal sides of bilateral mandibular fourth premolars in four beagle dogs. After elevating a full-thickness flap, exposed root surfaces were planed thoroughly. The 16 defects were assigned randomly to one of the following experimental conditions: CPC, CPC+EMD, EMD, and open flap debridement (OFD). Ten weeks post-surgery, the animals were sacrificed, and histologic specimens were prepared for histomorphometric evaluation. RESULTS: Defect sites treated with EMD only exhibited varying degrees of new cementum and new bone formation, whereas the OFD group presented only limited new cementum and bone formation. Defect sites where a CPC wall was implanted (CPC and CPC+EMD groups) revealed significantly greater regeneration of new bone and new cementum than in the EMD and OFD groups. No significant differences were observed between the CPC and CPC+EMD groups. CONCLUSIONS: CPC walls with and without EMD promoted regeneration of alveolar bone and cementum in 1-wall infrabony defects. Space and stable wound healing are believed to be crucial for periodontal regeneration in non-contained infrabony defects.     

Histologic evaluation of new attachment apparatus formation in humans. Part I

Part I of this three-part human study evaluated the formation of a new attachment apparatus (bone, cementum, and periodontal ligament) on pathologically exposed root surfaces in an open and closed environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Attempts were made to initiate the formation of a new attachment apparatus by flap curettage, root planing, coronectomy, and submersion of vital roots beneath the mucosa. Nonsubmerged defects were treated by the same surgical technique and served as controls. Biopsies were obtained at 6 months and regeneration was evaluated histometrically by two investigators who were unaware of the treatment performed. Data from 9 patients with 25 submerged and 22 nonsubmerged defects were submitted for statistical analysis. Results indicate that a new attachment apparatus did not form in any of the 22 nonsubmerged teeth; a new attachment apparatus did form in a submerged environment (0.75 mm); significantly more new attachment apparatus (P less than 0.05), new cementum (P less than 0.01), new connective tissue (P less than 0.05), and new bone (P less than 0.02) formed in submerged defects; new cementum was cellular in nature and formed equally well on old cementum and dentin. Greater percent positive regeneration of the attachment apparatus and all component tissues occurred in submerged defects and no extensive root resorption, ankylosis, or pulp death was observed on submerged or nonsubmerged roots.     

Comparison of platelet pellet with or without guided tissue regeneration in the treatment of class II furcation defects in dogs

The purpose of this study was to compare histological effectiveness of platelet pellet (PP), which has higher platelet content than platelet-rich plasma, and the combination of PP/guided tissue regeneration (GTR) for class II furcation defects in dogs. The mandibular second, third, and fourth premolars of both sides in four dogs were used. Class II furcation defects (5 mm in height and 2 mm in depth) were surgically created. Five weeks after the first operation, second premolars were treated with scaling and root planing (group 1); right third and fourth premolars received PP (group 2), and left premolars received the combination of PP/GTR (group 3). Percentage of cementum and alveolar bone formation were evaluated by histometric analysis after a healing period of 12 weeks. There was new cementum along with periodontal ligament and coronal growth of alveolar bone in all groups. Cementum formation was significantly higher in groups 2 and 3 compared to the control group (P < 0.05) with no significant difference between groups 2 and 3. Limited alveolar bone formation was statistically similar in all groups (P > 0.05). It is concluded that both PP and the combination of PP/GTR are effective in the treatment of class II furcation defects in dogs. PP thus appears to be a suitable alternative material in the regenerative periodontal therapy.     

Favorable healing following space creation in rhBMP-2-induced periodontal regeneration of horizontal circumferential defects in dogs with experimental periodontitis

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is believed to be capable of inducing periodontal regeneration. However, the risk of aberrant healing events, such as root resorption and ankylosis, has been reported. We hypothesized that implantation of BMP-containing carriers directly on the root planed surface may be the cause of unfavorable healing. The purpose of this study was to evaluate the influence of a 1 mm spacer membrane, which separated the rhBMP-2 in polymer-coated gelatin sponge (PGS) and the root surface, on periodontal regeneration of experimentally induced horizontal defects in dogs. METHODS: Horizontal circumferential periodontal defects were surgically created, and experimental periodontitis was induced in 72 maxillary and mandibular premolars of four male beagle dogs. The recipient sites of each quadrant received: 1) rhBMP-2/PGS (B group) (rhBMP-2 at 1.0 mg/ml, total implant volume/ site approximately 7.2 microl) (n = 24); 2) rhBMP-2/PGS with a spacer membrane (PB group) (n = 24); and 3) physiological saline (PS)/PGS as a control (P group) (n = 24). One quadrant was left untreated. Dogs were sacrificed at 12 weeks post-surgery, and healing was evaluated histologically. RESULTS: Both groups treated with rhBMP-2/PGS demonstrated enhanced new bone formation and connective tissue attachment with cementum regeneration when compared to the control group. Sites treated with rhBMP-2/PGS showed a greater degree of bone formation than sites treated with rhBMP-2/PGS and spacer membrane, although the latter sites showed no ankylosis. CONCLUSIONS: Implantation of rhBMP-2/PGS enhances bone formation and connective tissue attachment in horizontal circumferential defects. In addition, the use of a spacer membrane reduces the degree of bone formation, but minimizes ankylosis.     

Healing after root reimplantation in the monkey

The aim of the present investigation was to evaluate the regenerative potential of the periodontal tissues following tooth reimplantation using a model which excluded the dentogingival epithelium from the process of healing. Maxillary and mandibular incisors, premolars and molars of 5 monkeys were used. Following root filling of all experimental teeth, the teeth were divided into 3 experimental groups. In 1 group, the teeth were extracted following the elevation of full thickness flaps. The crowns were separated from the roots at the level of the buccal cemento-enamel junction and the roots immediately reimplanted into their sockets. The flaps were replaced and sutured to accomplish complete coverage of the roots. In a 2nd group, the teeth were subjected to the same experimental procedure, but in addition, the buccal alveolar bone was removed to about half its original height prior to root reimplantation. The teeth of the 3rd group were subjected to identical experimental procedures as for group II with the addition that the buccal root surfaces were planed to the level of the surgically created bone crest. The animals were sacrificed after 6 months of healing. The jaws were removed and histological specimens prepared for microscopic examination. The results showed that a complete fibrous re-attachment formed onto roots on which the original periodontal ligament tissue was preserved. This occurred irrespective of whether the roots were reimplanted into sockets with normal (group I) or reduced (group II) bone height. When the original periodontal ligament tissue was removed by root planing before reimplantation (group III), healing resulted in a significant amount of new connective tissue attachment. However, coronal to the newly formed fibrous attachment, the root surface frequently showed signs of resorption and particularly so in those roots which remained covered by the soft tissue during the entire course of healing. In the majority of the roots which perforated the covering soft tissue during the early phase of healing, the dentogingival epithelium had migrated apically into contact with the coronally generated fibrous attachment. In these cases, root resorption was never discernible. New bone formation occurred to a variable extent in the roots of groups II-III. No relationship was found, however, between the amount of connective tissue reattachment or new attachment and newly formed alveolar bone, which in turn indicates that bone tissue regrowth and periodontal ligament regeneration are unrelated phenomena.     

Periodontal new attachment therapy]

The ultimate goal of periodontal therapy includes not only the arrest of progressive periodontal disease, but also the restitution of those parts of the supporting apparatus which were destroyed by the disease. Regeneration of periodontal structures dissolved because of periodontal disease is the goal of reconstructive periodontal treatment procedures. The achievement of this goal requires the formation of new cementum with inserting collagen fibers of previously periodontitis involved root surfaces possibly with a concomitant regeneration of supporting alveolar bone. Healing, after periodontal therapy, leads to the formation of long junctional epithelium, root resorption, ankylosis, etc. These are repair process and not one of regeneration. But guided tissue regeneration seems to lead to regeneration with active periodontal ligament cells.     

Periodontal repair in dogs: effect of saliva contamination of the root surface

This study evaluated whether periodontal repair following reconstructive surgery may be compromised by saliva contamination of the root surfaces during the surgical procedure. Circumferential periodontal defects, 5 to 6 mm in vertical dimension, were surgically created in the mandibular premolars in 9 beagle dogs and immediately treated. The denuded root surfaces in left and right jaw quadrants in 4 dogs were treated with either filter sterilized saliva or saline, while in the remaining 5 dogs the root surfaces were treated with unfiltered saliva or saline. The wounds were closed and allowed to heal for 4 weeks. The dogs were sacrificed and tissue blocks prepared for histometric analysis. Results showed no difference between teeth treated with filtered or unfiltered saliva and the saline treated controls. Connective tissue repair to the root surfaces exceeded 70% of the defect height in all experimental groups. Regeneration of cementum and alveolar bone was limited and did not exceed 30% of the defect height. The results indicate that contamination of the root surface by saliva during the surgical procedure does not necessarily compromise connective tissue repair to the root surface.     

Healing of periodontal lesions in monkeys following the guided tissue regeneration procedure A histological study

Abstract The purpose of the present investigation was to study histologically the healing of periodontal lesions in monkeys during the first 9 weeks following periodontal reconstructive surgery according to the principle of guided tissue regeneration. Horizontal interproximal lesions and through-and-through bifurcation defects were surgically produced in 2 adult monkeys. Following removal of granulation tissue and root planing, notches indicating the level of the reduced bone level were prepared in the root surfaces. Sterile teflon membranes were then adjusted to cover the defects, and the gingival flaps were sutured in a coronally displaced position. Sacrifice of the animals was scheduled to allow for observation periods of 1, 3, 4 and 9 weeks. Evaluation of histological specimens revealed a continuous growth of new connective tissue during a period of 4 weeks. The coronal growth of new tissue did not increase significantly between 4 and 9 weeks. New cementum had formed in the most apical part of one notch after 1 week of healing, and following 3 and 4 weeks, new cementum with inserting periodontal ligament fibers were observed in all notches and to a varying degree, also more coronally on the root surfaces of both interproximal and bifurcation defects. Limited regrowth of alveolar bone was observed in the 9-week specimens. Judged from the course of the blood vessels within the newly formed connective tissue in the defects, the tissue in the central part of the defects had originated from the alveolar bone, whereas the tissue adjacent to the root surfaces seemed to have its origin in the residual periodontal ligament.