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The aim of the present study was to examine if new cementum and new attachment may form during healing of a wound prepared in such a way that preference is given to periodontal ligament cells to repopulate the wound area adjacent to a root which has been surgically deprived of its periodontal ligament and cementum layer. The maxillary lateral incisors and mandibular canines in three monkeys were used for experimentation. Following elevation of a mucoperiosteal flap, the buccal and approximal alveolar bone was removed within an area extending from the mid-root level to a level 2 mm apical to the marginal bone crest. Following bone removal, the root surfaces were curetted in order to remove the cementum layer. Notches were prepared in the roots to demarcate the denuded root portion. Prior to repositioning of the tissue flap a millipore filter was placed over the treated area in order to prevent the gingival connective tissue from coming into contact with the root surface during healing. The animals were sacrificed 6 months after surgery. The jaws were removed and histological sections of the experimental teeth and surrounding periodontal tissues were produced. New cementum with inserting collagen fibers was observed on the curetted root surfaces. However, this result of healing did not consistently occur along the entire length of the curetted root portion. In the coronal part of the wound, healing was frequently characterized by connective tissue adhesion to the root surface without signs of cementum formation and fibrous attachment. The results of the experiment suggest that the periodontal ligament cells possess the ability to reestablish connective tissue attachment.

The aim of the present study was to evaluate whether a regenerative surgical procedure, based on guided tissue regeneration, could predictably result in the formation of a new attachment in human teeth. The material included 12 teeth in 10 patients with advanced periodontal disease. Following flap elevation, scaling, root planing and removal of granulation tissue, a teflon membrane was placed over the denuded root surface in such a way that the epithelium and the gingival connective tissue were prevented from reaching contact with the root during healing. The flap was replaced on the outer surface of the membrane and secured with interdental sutures. This design of wound preparation gives preference to the cells originating from the periodontal ligament (PDL-cells) to repopulate the wound area adjacent to the root. Histologic analysis of the result of treatment was made in 5 of the 12 teeth scheduled for extraction. In the remaining 7 teeth, the result was evaluated using clinical measurements. The result of healing disclosed that in all teeth treated, substantial amounts of new attachment had formed. This suggests that predictable restitution of the attachment apparatus can be accomplished by using a method of treatment which is based on the principle of guided tissue regeneration.

This report describes the surgical treatment of advanced periodontitis in a haemophilic patient with inhibitors to Factor VIII. The treatment was performed after substitution therapy with Factor VIII-concentrate, supported by local and systemic antifibrinolytic treatment with tranexamic acid. No complications developed postoperatively, and after 9 months, the patient did not show recurrence of periodontal disease. Although the present case shows, that even severe periodontitis can be treated surgically in haemophilic patients with inhibitors to Factor VIII, this should not be done unless it is absolutely necessary. The treatment of periodontal disease in such patients should be instituted as early as possible in order to prevent the need for extensive surgery or dental extractions.

The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing. A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.

The present study was designed to examine whether coronal growth of granulation tissue originating from the periodontal ligament is a prerequisite for new attachment formation. In each of 4 monkeys, 1 central incisor and 2 first molars in the maxilla and the mandible were selected for experimentation. Angular bony defects were surgically produced to the mid-root level around each single root after crown resection and root separation of the multirooted teeth. The periodontal ligament tissue and the root cementum were removed to the bottom of the bony defects. In half the number of the teeth, an elastic ligature was placed tightly around each root at the bottom of the defects (test roots). In the remaining teeth, an elastic ligature was placed loosely around each root at the same level (control roots). All roots were subsequently covered by laterally displaced flaps. After 3 months of healing, the animals were sacrificed and the jaws removed and placed in fixative. Following decalcification, histological sections of the experimental roots and their surrounding periodontal tissues were produced. The histological analysis disclosed that new attachment had former to a level coronal to the elastic ligature in 10 of 14 control roots but in only 1 of 18 test roots. The results indicate that the repopulation of a detached root surface by cells from the periodontal ligament is a prerequisite for new attachment formation.

This study examines whether blocking of cell division by stress-inducing electrical stimulation can be maintained for a prolonged period of time and whether this results in the accumulation of a large number of cells ready to divide when the block is released. A total of 96 rats was subjected to electrical stimulation at intervals of 30 min for periods of 2, 4, 6 or 12 hr. Groups of animals were killed every second hour during these stimulation periods. After 2, 4 and 6 hr groups of animals were exempted from further stimulation and killed 2 or 4 hr later. After termination of the 12 hr stimulation period, groups of animals were killed every second hour during the succeeding 24 hr. Forty-eight animals were left undisturbed and served as controls. Two and a half hours prior to death, each of the experimental and control animals was injected intraperitoneally (i.p.) with colchicine. Histological sections of the palatal mucosa were prepared and the numbers of arrested metaphases were counted. The electrical stimulation for 2, 4, 6 and 12 hr consistently resulted in a reduced number of cells entering mitosis, indicating a blockade at the G2/M transition. However, with an increase in the length of electrical stimulation, an increasing number of cells passed the block, while a decreasing number entered mitosis during the first 4 hr following cessation of the stimulation. The sum of metaphases accumulated during the various stress periods and the following 4 hr was always similar and consistently lower than the number of metaphases accumulated in the control animals within the same time periods. This observation indicates that, during stress-inducing electrical stimulation and the succeeding 4 hr, only a defined number of cells can enter the mitotic phase. Thus, in addition to the block at the G2/M transition, there appears to be another block of cell division at an earlier stage in the cell cycle.

The carcinogen 4NQO was applied to the palates of rats for 2 weeks or 2 months. Eight weeks after termination of carcinogen application, animals were injected with colchicine and sacrificed at intervals of 3 h during a 24 h period. Histological sections were produced and the number of arrested metaphases counted in the palatal epithelium. The two groups had the same daily mitotic rate and exhibited a circadian rhythm in mitotic activity similar to that demonstrated in normal oral mucosa of nocturnal animals. Carcinogen was applied to the palates of other groups of rats for 2 weeks or 2 months. Animals treated with saline served as controls. At various time points during and after carcinogen treatment eight rats from each group were killed. Four of these animals were injected with colchicine prior to sacrifice and the number of arrested metaphases counted in the palatal epithelium. In the noncolchicinized rats all mitotic phases were counted. After cessation of carcinogen application the mitotic rates, the mitotic counts and the mitotic durations did not differ from those of control animals, indicating that the carcinogen had failed to induce irreversible changes in the cell population kinetics of the palatal epithelium.

The present study was designed to evaluate if the conditions for reformation of a connective tissue attachment are less favorable on root surfaces which have lost their fibrous attachment because of periodontal disease than on root surfaces surgically deprived of their attachment apparatus. In each of 4 Green monkeys, 2 maxillary and 2 mandibular teeth were selected for experimentation. Periodontal breakdown was produced and allowed to progress to the mid-root level around one of the experimental teeth in both the maxilla and mandible by placing elastic ligatures around the neck of these teeth. 3 months after removal of the ligatures, the crown of the teeth was resected and the epithelium and the subjacent granulation tissue were removed. Using a diamond bur, circumferential defects similar to those obtained by the ligature induced destruction were then produced around the remaining 2 experimental teeth following resection of the crown. The root cementum on both groups of teeth was removed to the level of the reduced bone height. Finally, all roots were submerged to complete coverage by a mucosal flap. After 3 months of healing, the animals were sacrificed and the jaws removed and placed in fixative. After decalcification, histological sections of the experimental roots and their surrounding periodontal tissues were produced. No histological differences in the result of healing were discernible between the specimens of previously periodontitis-affected roots and roots with surgically created defects. New cementum with inserting collagen fibers had formed in the apical part of the instrumented surface in both groups of teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Pocket depth, attachment level and bone level assessments were carried out using flexible splints to produce readily identifiable reference points and to standardize the probing spot and the direction of probe insertion. The pocket depth and attachment level measurements were carried out twice at intervals of 3 weeks, both before and 3 months after periodontal treatment. The level of alveolar bone was measured by transgingival probing ("sounding") and again following elevation of a mucoperiosteal flap. The measurements were made with a periodontal probe to the nearest higher millimeter. Complete agreement was found between the first and second measurements of pocket depths and attachment level for approximately 60% of the examined surfaces, both before and after periodontal treatment. A deviation of 1 mm or less was found for approximately 95% of the surfaces, and the difference between the first and second measurement never exceeded 3 mm. When transgingival probing measurements were compared to the measurements of the periodontal bone level assessed after elevation of a mucoperiosteal flap, complete agreement was found for 60% of the surfaces, and a deviation of 1 mm or less was found for 90% of the surfaces. No discrepancy exceeding 3 mm was observed. The results of this study indicate that readily identifiable reference points can be produced by flexible splints in assessments of pocket depth, attachment level and bone level alterations in studies on the effect of periodontal treatment.

The present study was undertaken to enable histological assessment of attachment level alterations following repeated scaling and root planing in periodontal sites with "normal" sulcus/pocket depth. Two monkeys (Macaca cynomolgus) were used. During a period of 6 months, scaling was carried out once every 2 weeks at the buccal surfaces of premolars and molars on the right side of the jaws. The contralateral teeth served as untreated controls. Six months after the completion of treatment (1 year after the start of the experiment), the animals were sacrificed and histological sections of all test and control teeth were produced. In these sections the distances between the cemento-enamel junction (CEJ) and the apical extent of the junctional epithelium (JE) and between the JE and the alveolar bone crest (BC) were measured. The results revealed that repeated scaling and planing resulted in an average loss of connective tissue attachment amounting to 0.39 mm and in a corresponding recession of the alveolar bone crest. The findings are discussed in relation to recent observations from clinical trials demonstrating loss of clinical attachment following repeated scaling and root planing in sites with shallow gingival pockets.

Previous studies have shown that procedures commonly used in studies of cell population kinetics in laboratory animals cause a transient block of the entrance of cells into mitosis. The purpose of the present study was, therefore, to examine whether the handling of animals in conjunction with the administration of colchicine affects the results obtained by the metaphase arrest technique. Groups of rats were injected with colchicine or saline at 1300 h and sacrificed at regular intervals during the following 140 min. Histological sections of the palatal mucosa were produced and the number of metaphases was assessed in the epithelium. In both the saline-treated and colchicine-treated groups the numbers of metaphases decreased immediately after injection and reached a minimum within 30 min. After that time a transient increase was observed in the saline group, whereas the number of metaphases in the colchicine-treated group increased continuously during the experimental period. These results indicate that colchicine takes effect after a delay period of 30 min and that the handling procedures in conjunction with the administration of colchicine provoke a transient block of the entry of cells into mitosis. The second part of the study was designed in such a way that the number of metaphases collected during a 2 h period under the influence of stress induced by injection of colchicine could be compared with the number of metaphases collected during the same time period without the influence of stress.(ABSTRACT TRUNCATED AT 250 WORDS)

This study has shown that treatment with distally extending cantilever fixed partial dentures is a favorable alternative to treatment with removable partial dentures in elderly patients with reduced dentition. In patients with anterior teeth and one or two premolar teeth remaining in the mandible, sufficient occlusal stabilization for a maxillary complete denture was provided by a two- or three-unit cantilever fixed partial denture. A pronounced improvement in chewing function and stability of the maxillary denture was expressed, even by patients who were previously well adapted to wearing removable partial dentures.

The fate of vital and devitalized grafts of mature concellous bone from the jaws were studied in interradicular lesions in monkeys. 98 bifurcation defects were produced in premolars and molars and maintained by periodontal dressing inserted for four weeks. Ten to 15 weeks later fresh cancellous bone was transplanted into 32 defects. Other cancellous bone grafts were divitalized by boiling and transplanted into 34 bifurcations. The remaining 32 defects received no grafts. The animals were sacrificed to yield observation periods from 0 to 90 days. After decalcification of the specimens and embedding in paraffin, serial sections were cut at 8 microns and stained. The fate of viable and dead transplants were similar during the healing of the interradicular lesions. Except for a few osteocytes which seemed to survive transplantation in the fresh cancellous bone, the osteocyte lacunae were devoid of cells in both types of transplants after 1 week. The deepest located bone grafts became incorporated in new bone developed from the interradicular septum. The more superficially located grafts were rejected or were surrounded by a cementum-like substans. The influence of the grafts on bone regeneration was small and based solely on their osteoconductive effect.

It has been shown that the connective tissue base determines the epithelial surface characteristics. Although there is no apparent difference between the connective tissues underlying the subcular and the surface gingival epithelium, the sulcular epithelium is not keratinized as is the gingival surface. The influence of the sulcular environment in determination of keratinization was explored in three adult Rhesus monkeys. Twenty-four intrasulcular mucoperiosteal flaps were elevated beyond the buccal mucogingival border, were turned inside out and sutured to leave the sulcular epithelium exposed on the surface. Short term speciments (1 hour to 7 days) were obtained from one monkey which received H3 thymidine 1 hour prior to sacrifice. Biopsies were obtained from the other two monkeys covering intervals of 1 week to 2 months. The findings indicate that the sulcular epithelium has potential for keratinization. The contact to the tooth appears to determine the lack of keratinization of the sulcular epithelium.

The aim of the present experiment was to study whether new connective tissue attachment can occur to root surfaces which have been exposed to the oral environment and subsequently implanted into bone tissue. Twelve teeth in three beagle dogs were subjected to progressive periodontal breakdown to half the root length by placing cotton floss ligatures around the neck of the teeth. Following crown resection and root hemisection, the teeth were root filled and the roots thoroughly scaled and planed. Each root was extracted and implanted into bone cavities prepared in edentolous areas of the jaws in such a way that epithelial migration into the wound and bacterial infection were prevented during healing. Root implantation and sacrifice of the animals were scheduled to allow for observation periods of 1, 2 and 3 months. The results demonstrated that new connective tissue attachment did not occur to root surfaces which had been exposed to the oral environment, but healing was characterized by repair phenomena, i.e. mainly root resorption and ankylosis. In those areas of the roots where periodontal ligament tissue was preserved following tooth extraction, a functionally oriented attachment apparatus was reformed. The results indicate that in addition to apical migration of junctional epithelium and regrowth of subgingival plaque, the type of cells which repopulate the wound area may jeopardize new connective tissue attachment.

The present investigation was undertaken to examine whether a new connective tissue attachment will form on previously periodontitis-involved roots when reduced but healthy periodontal ligament tissue persists following periodontal treatment and the epithelium is prevented from migrating into the wound. In each of 4 monkeys, periodontal tissue breakdown was induced around one maxillary and one mandibular second premolar or first molar by placing orthodontic elastics around the teeth. The elastics were kept in situ until about 50% of the supporting tissues had been lost. 3 months following removal of the elastics, the crowns of the teeth were resected. The pocket epithelium and subjacent granulation tissue were excised and the cementum of the periodontitis-involved part of the roots was removed using a diamond bur. The roots were covered with a mucosal flap. The animals were sacrificed after 3 months of healing. The jaws were removed and histological sections of the experimental roots including their surrounding periodontal tissues were produced. The microscopic analysis disclosed that in all roots, new cementum with inserting collagen fibers had formed in the apical portion of the previously exposed root surfaces. It was always in continuity with the original cementum layer apical to the instrumental part of the root and was thickest in its apical portion, becoming gradually thinner in the coronal direction. In the roots, which for the entire length of the study remained covered by the oral mucosa, the extension in the coronal direction of this newly formed fibrous attachment amounted to an average of 1.0 mm with a range from 0.1 mm to 2.6 mm. These findings were interpreted to mean that new attachment is formed by coronal migration of cells originating from the periodontal ligament.

This study was undertaken in order to evaluate the effect of root planing as compared to that of surgical periodontal treatment in patients with advanced periodontal disease. 17 patients with advanced periodontal disease participated in the study. After the initial examination, the teeth were scaled and the patients were given instruction in performing proper oral hygiene. The hygienic phase for the individual patient was continued until less than 20% of the tooth surfaces demonstrated plaque at 2 succeeding appointments. After re-assessment of the periodontal status, 1 side in both the maxilla and mandible was treated with modified Widman flap surgery. In 1 of the remaining quadrants, in the maxilla or mandible, reverse bevel flap surgery was used. Bone contouring was not performed in any of the surgical procedures. The last quadrant was subjected to meticulous root planing under local anesthesia. Subsequently, the patients were recalled every second week for professional tooth cleaning. The periodontal status of each patient was assessed 3 and 6 months following treatment. Root planing resulted in considerable reduction in pocket depth, although more shallow pockets were obtained following modified Widman flap and reverse bevel flap surgery. Clinical gain of attachment was obtained following all 3 modalities, but root planing resulted in slightly more gain of attachment than the 2 surgical procedures.

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.

The purpose of the present study was to localize in the cell cycle, the site of the stress-induced blockage of cells entering the mitotic phase, and to estimate the length of time this block is effective. A total of 140 rats were subjected to electrical stimulation applied by a live metal grill in the bottom of their cages. Forty animals left undisturbed in the cages were used as controls. At various intervals after the start of electrical stimulation, groups of animals were killed and histologic sections were prepared of the palatal mucosa. The number of prophases, metaphases, and ana/telophases was counted in the epithelium in three sections of each animal. Electrical stimulation for 1 min resulted in a blocking of the entrance of cells into mitosis, followed by a transient increase in the number of mitotic figures to a level much higher than that of the controls. Electrical stimulation for 10 min resulted in the maintenance of the blocking effect for approximately 45 min. By renewed electrical stimulation the period of blockage was extended for a further 35 min. In each experiment the number of prophases decreased immediately after the start of electrical stimulation, indicating that the site of the blockage of the entrance of cells into mitosis is located near the G2/M transition.