Regeneration and repair after biologic treatment of root surfaces in monkeys. II. Proximal surfaces posterior teeth

Pre-clinical models for oral and periodontal reconstructive therapies

The development of new medical formulations (NMF) for reconstructive therapies has considerably improved the available treatment options for individuals requiring periodontal repair or oral implant rehabilitation. Progress in tissue engineering and regenerative medicine modalities strongly depends on validated pre-clinical research. Pre-clinical testing has contributed to the recent approval of NMF such as GEM 21S and INFUSE bone grafts for periodontal and oral regenerative therapies. However, the selection of a suitable pre-clinical model for evaluation of the safety and efficacy of a NMF remains a challenge. This review is designed to serve as a primer to choose the appropriate pre-clinical models for the evaluation of NMF in situations requiring periodontal or oral reconstruction. Here, we summarize commonly used pre-clinical models and provide examples of screening and functional studies of NMF that can be translated into clinical use.

The effectiveness of different root debridement modalities in open flap surgery

It is unclear what degree of roughness or smoothness result from use of hand instruments alone in comparison to the use of hand instruments in combination with other aids and how it may effect the grade of cleanliness. The aim of this study was to determine in vivo whether the combination of hand instruments with other aids can increase the effectiveness of root debridement. 11 patients with holpless 4 mandibular incisors were involved in this study. After elevating a lingual and buccal mucoperiosteal flap, the 4 incisors were randomly treated with either: (1) no treatment (control); (2) 5-min scaling (method 1); (3) 4-min scaling and 1 min instrumentation with a perio-diamond bur (15 microm) (method 2); (4) 3-min scaling, 1-min instrumentation with a perio-diamond bur (15 microm) and 1 min with an air abrasive system (method 3). The cleanliness of the surface was determined using the method of Eschler and -Rapley. The degree of roughness (Ra and Rt) were measured with a laser beam (computer supported optical surface sensor system). In addition, an SEM analysis was performed. With regard to the remaining calculus (surface cleanliness), method 3 yielded significantly better results than the other 2 methods. The roughness analyses also exhibited that method 3 is superior to methods 1 and 2. The qualitative results of the SEM investigations demonstrated the most homogeneous and smooth surfaces with method 3. Root debridement in vivo was most significant using a combination of different treatment modalities (i. e., curettes, perio-diamond bur and air abrasive system).

Non-human primates used in studies of periodontal disease pathogenesis: a review of the literature

The inability to examine initiation and progression of periodontal disease and to assess certain therapies in humans has led to a great interest in the use of animal models in periodontal research. Some of the most prominent animals used are non-human primates. This article reviews the characteristics of non-human primate models in periodontal health, in the transition from health to gingivitis to periodontitis, and in experimental gingivitis and periodontitis. Where possible, the results of these studies are compared with results from human studies. Only a few studies have compared in detail the anatomy, physiology, immunology, and tissue interactions in monkeys with those of humans. With the exceptions of differences and variations in size of the dentition, the number of each tooth type as well as larger canines, presence of diastemata between anterior teeth, and an edge-to-edge relationship of the incisors, the dental and periodontal anatomy of non-human primates seem quite similar to that of humans. Clinically healthy gingiva can be established and maintained in non-human primates, and gingivitis as well as periodontitis occur in these animals. It is possible to induce experimental periodontitis by placement of peri-dental silk ligatures or orthodontic elastics as well as by surgical removal of alveolar bone. Although the most appropriate model for studies of periodontal disease pathogenesis in non-human primates appears to involve the application of silk ligatures, some difficulties may occur in establishing periodontal break-down by using this model. Many clinical, histological, microbiological, and immunological characteristics of spontaneous and experimental marginal inflammation in most non-human primates are similar to those in humans. The most significant differences between small non-human primates and humans are the very limited number of lymphocytes and plasma cells in the inflammatory infiltrate of squirrel monkeys (Saimiri sciureus) and marmosets. Therefore, the use of squirrel monkeys and marmosets may not be appropriate in many studies of periodontal disease pathogenesis. The most significant microbial differences between macaque species and humans are a lower proportion of Actinomyces species, the presence of a catalase-producing Prevotella melaninogenica strain, and the high carrier rate for Actinobacillus actinomycetemcomitans in subgingival plaque of macaque species. The significance of these differences is presently unknown. It is concluded that the use of many non-human primate species due to the apparent close anatomic and biologic similarities to humans is appropriate in experimental studies of periodontal disease, provided the use of laboratory animals is requisite and lower species are not applicable.(ABSTRACT TRUNCATED AT 400 WORDS)

Effectiveness of open flap root debridement with rubber cups, interdental plastic tips and prophy paste. An SEM study

This study was designed to ascertain whether conservative cleaning of surgically-exposed root surfaces can achieve complete plaque removal. 10 single-rooted teeth (40 surfaces) from 4 patients with advanced periodontitis were included in the study. After flap reflection, the root surfaces were cleaned using only rubber cups, EVA plastic tips and prophy paste. No attempt was made to remove calculus. Immediately after treatment, the teeth were extracted. Then root surfaces were systematically examined in the scanning electron microscope to detect any residual bacteria (plaque). 27 of the 40 treated root surfaces were plaque-free. On the other 13 root surfaces, only a few isolated small islands of plaque were detected. On the other hand, relatively extensive areas of the root surfaces exhibited calculus. Bacterial plaque accumulation was routinely observed on the rough calculus surfaces and at the periphery of the hard deposits. These results demonstrate that the instruments used in this study can successfully remove plaque from exposed root surfaces. However, subgingival calculus that is firmly attached to root surfaces virtually always harbors plaque bacteria; such deposits require more aggressive instrumentation (scalers, curettes) for removal.

Role of "diseased" root cementum in healing following treatment of periodontal disease. A clinical study

This clinical trial was undertaken to examine whether root debridement in the treatment of periodontal disease must include the removal of the exposed cementum in order to achieve periodontal health. The study included 11 adult patients with moderate to advanced periodontal disease. In a split-mouth design, the dentition of each patient was by random selection divided into test- and control quadrants comprising the incisors, canines and premolars. Following a baseline examination, all patients were given a case presentation and a detailed instruction in self-performed oral hygiene measures. The patients were then subjected to periodontal surgery. Following reverse bevel incisions, buccal and lingual mucoperiosteal flaps were elevated and all granulation tissue was removed. In 2 jaw quadrants (control quadrants) in each patient, the denuded root surfaces were carefully scaled and planed in order to remove soft and hard deposits as well as all cementum, using hand instruments and flame-formed diamond stones. In the contralateral quadrants (test quadrants) the roots were not scaled and planed but soft microbial deposits were removed by polishing the root surfaces with the but soft microbial deposits were removed by polishing the root surfaces with the use of rubber cups, interdental rubber tips and a polishing paste. Calculus in the test quadrants was removed by the use of a curette, but precaution was taken to avoid the removal of cementum. The flaps were repositioned to their original level and sutured. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks for a 3-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of citric acid and lyophilized autologous plasma on healing following periodontal flap surgery in monkeys

The purpose of this histologic, histometric, and autoradiographic study was to examine the effect of citric acid conditioning and lyophilized autologous plasma (LAP) application on healing following periodontal flap surgery. Mucoperiosteal flaps were elevated in six rhesus monkeys using the modified Widman flap procedure. A total of 24 quadrants were treated, each included the first and second premolar and first and second molar teeth. Cementum was removed from the exposed root surfaces, and reference notches were inscribed into the roots at the alveolar bone margin. Two treatment modalities were employed: (1) surgery plus citric acid conditioning, to serve as control and (2) surgery plus citric acid followed by LAP application (400 mg/ml saline). Flaps were returned to their preoperative positions and sutured. Animal sacrifices were scheduled to provide observations 3, 7, 14, 21, 28, and 45 days after surgery. Each monkey received an intravenous injection of tritiated thymidine, 1 microCi/gm of body weight, 1 hour before it was killed. Tissue specimens were processed for evaluation following standard procedures. Histologically, tissue sections were examined for: (1) proliferation and attachment of epithelium, (2) organization and maturation of periodontal fibers, (3) inflammatory cell types, (4) presence or absence of new cementum deposition, and (5) degree of vascularity of the tissues. For histometric evaluation, the radicular notches were used as reference points. The distances examined histometrically were: (1) from the root surface notch to the alveolar bone crest, (2) from the root surface notch to the apical extent of the junctional epithelium, and (3) from the free gingival margin to the apical extent of the junctional epithelium. For autoradiographic evaluation labeled cells were counted in five spatial compartments at 400 X magnification: (1) oral epithelium, (2) crevicular area, (3) supracrestal connective tissue, (4) coronal periodontal membrane, and (5) coronal bone marrow. For each the histometric and autoradiographic evaluation involved a total of 36 tissue sections per quadrant (9 sections per tooth). Tooth and quadrant means were obtained for each monkey. The plasma-treated and control quadrants were compared at each time point by the paired t test. N = 2 monkeys were used for each comparison. Histologic results showed that in teeth that were acid-conditioned after root planing, the epithelium often migrated apically reaching the radicular notch. Those teeth that were conditioned and subsequently treated with LAP demonstrated fiber attachment to the planed root surface and little or no epithelial downgrowth.(ABSTRACT TRUNCATED AT 400 WORDS)

Biologic preparation of diseased root surfaces. An in vitro study

The study evaluated the effect of 2% sodium desoxycholate combined with whole plasma from a single donor on gingival fibroblast attachment to diseased root surfaces. Twenty extracted periodontally involved teeth were cut into halves buccolingually and sterilized by moist heat under high pressure. The diseased root surface of each control half was rubbed with a sterile cotton pellet saturated with Dulbecco's phosphate-buffered saline (PBS). The diseased root surface of each experimental half was rubbed with a sterile cotton pellet saturated with 2% sodium desoxycholate and then rubbed with a pellet soaked in human plasma. The control and experimental halves were placed in separate petri dishes, and a fibroblast cell suspension was added to each dish. The mean number of attached cells per half tooth was calculated for each group. Tooth surfaces treated with PBS (controls) showed a mean of 307 +/- 63 attached cells for 17 tooth halves; the experimental treated surfaces exhibited a mean of 650 +/- 130 attached cells for 16 halves. The difference between these numbers was statistically significant (P less than 0.01). These findings suggest that the desoxycholate/plasma combination enhanced in vitro fibroblast attachment to diseased root surfaces.