Connective tissue attachment formation following exclusion of gingival connective tissue and epithelium during healing

The present investigation was designed to evaluate the potential for reformation of connective tissue attachment on exposed and planed root surfaces by preventing the dentogingival epithelium and the gingival connective tissue from interfering with healing following periodontal surgery. Following the elevation of soft tissue flaps, the buccal and proximal alveolar bone of 24 teeth (48 roots) was removed to mid-root level in 6 monkeys and the exposed root surfaces were carefully planed in order to remove the root cementum. Before the flaps were repositioned and sutured, a membrane (Millipore® filter) was placed over the denuded part of the root surfaces of 16 teeth (test teeth) in order to prevent the epithelium and the gingival connective tissue from interfering with healing. The membrane was adjusted to cover the tooth surfaces from midcrown level to approximately l mm apical to the bone crest. No membranes were placed around the remaining 8 teeth (control teeth) before flap repositioning. The animals were sacrificed 6 months after surgery. The jaws were removed and histological sections of test and control teeth including their buccal periodontal tissues were produced. Nine of the test teeth had to be excluded from examination due to technical failures in the surgical procedure or tissue preparation. New cementum with inserting collagen fibers was observed on all remaining 14 test roots. The length of this newly formed fibrous attachment corresponded to approximately 50% of the distance from the apical extension of root planing to the cemento-enamel junction. In the majority of the control teeth no new attachment had formed but a “long” junctional epithelium was lining the root surfaces to the apical extension of root planing. In 3 control roots a small amount of new cementum with inserting collagen fibers was found in the most apical area of root planing. The results showed that the reformation of a connective tissue attachment was considerably favored by the placement of membranes which prevented the dentogingival epithelium and the gingival connective tissue from interfering with healing.     

Artificial periodontal defects around incisor teeth of beagle dogs

The aim of the present experiment was to investigate if it is possible to create deep periodontal defects around incisor teeth of beagle dogs with the use of orthodontic elastic bands, to investigate if this method is reproducible and predictable, and to evaluate if such defects possess the histopathological characteristics of naturally occurring periodontitis. In eight beagle dogs the dentogingival fibres around four upper incisors, ³I₃ and ²I₂, were cut to the level of the alveolar bone. Orthodontic elastic bands were placed in these deepened sulci and removed after 8 weeks. Clinical data (probing depth and gingival recession) were recorded at the start of the experiment, immediately following removal of the elastic bands, and 2, 6, 14, and 30 weeks thereafter. The dogs were sacrificed on different dates so that is was possible to analyse defects histometrically 3, 7, 15, or 31 weeks after elastic removal. Contralateral defects one week after elastic band removal served as controls. Micrographic color slides of the histological sections were analysed using a Ferranti-Cetec digitizer. Immediately after elastic band removal mean values for probing depth and gingival recession were approximately 5.5 mm and 2.0 mm, respectively. Histometrical assessments revealed a loss of attachment of approximately 3.0 mm. The differences in probing depths between Contralateral defects in the same dog were small indicating rather high reproducibility of the method. Because of wide variations in probing depth and histometrical dimensions between dogs, it was concluded that the present method is not fully predictable. Upon elastic removal values for probing depth decreased with approximately 1.5 mm, the result being a moderately deep defect of around 4 mm. Histometrically there was no evidence that the apical positioning of the junctional epithelium was reversible after elastic removal. However, alveolar bone repair could be demonstrated in the 7, 15, and 31 weeks specimens. It was concluded that because of this bone repair, the present defects do not possess all histopathological characteristics of naturally occurring periodontitis.     

Comparison of gingival crevicular fluid sampling methods in patients with severe chronic periodontitis

Background: The analysis of samplings from periodontal pockets is important in the diagnosis and therapy of periodontitis. In this study, three different sampling techniques were compared to determine whether one method yielded samples suitable for the reproducible and simultaneous determination of bacterial load, cytokines, neutrophil elastase, and arginine‐specific gingipains (Rgps). Rgps are an important virulence factor of Porphyromonas gingivalis, the exact concentration of which in gingival crevicular fluid (GCF) has not been quantified. Methods: GCF was sampled from four sites per patient (one sample per quadrant using two samples per method) in 36 patients with chronic periodontitis. One week later, the procedure was repeated with alternative methods. Variables determined were loads of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) and P. gingivalis, levels of interleukin‐6 and ‐8, activity of neutrophil elastase, and level of Rgps. Results: The detected cytokine levels were higher using paper strips compared to paper points. Bacteria were found in similar loads from paper strips and paper points. Rgps were only detectable in high quantities by washing the periodontal pocket. The level of Rgps correlated with the load of P. gingivalis. Conclusions: The use of paper strips was suitable for the simultaneous determination of microbial and immunologic parameters. Obtaining GCF by washing can be useful for special purposes. The gingipain concentration in periodontal pockets was directly determined to be ≤1.5 μM. This value indicated that most of the substrates of these proteases by in vitro assays identified until now can be easily degraded in P. gingivalis–infected sites.     

Women with a recent history of early-onset pre-eclampsia have a worse periodontal condition

OBJECTIVE: Pre-eclampsia is a complication of pregnancy characterized by systemic vascular dysfunction and pathological changes in placental arteries. Growing evidence of chronic infection as an aetiological factor in vascular diseases prompted us to study maternal periodontal disease in subjects with early-onset pre-eclampsia (<34 weeks). METHODS: A case-control study was carried out on 17 early-onset pre-eclamptic women and 35 controls with uncomplicated pregnancies in a period of 3-28 months postpartum. All were Caucasians. Full-mouth periodontal examinations were performed to determine the periodontal condition. Subgingival-plaque samples were analysed by anaerobic culture techniques for the presence of seven bacterial periodontal pathogens. Potential confounders as age, smoking, educational level and body mass index were determined. RESULTS: Severe periodontal disease was found in 82% of the pre-eclamptic and in 37% of the control group (p=0.009). After adjusting for age, smoking and educational level, the odds ratio was 7.9 (95% CI: 1.9-32.8). The periodontopathic microorganism Micromonas micros was more prevalent in the case group (p=0.040) while Campylobacter rectus was more prevalent in the control group (p=0.047). CONCLUSION: These results indicate that Caucasian women with a recent history of early-onset pre-eclampsia have a worse periodontal condition, as compared with women with uncomplicated deliveries.     

The effect of autogenous cancellous bone grafts on gealing of experimental furcation defects in dogs

Chronic, through-and-through, furcation defects were created in mandibular premolars of six beagle dogs. These defects were surgically treated without autogenous, cancellous, bone grafts. Healing sockets in the maxilla serged as donor sites. Block specimens were removed after eight weeks. All teeth from all dogs showed some reattachment after treartment as evidenced by newly formed cementum. None of the specimens showed complete regeneration, i.e.a periodontal membrane with new cementum all aroune the fornix of the furcation. Histometric measurements showed that the use of osseous grafts did not improve the results in the present experimental model.     

Vascular reactions in the periodontal ligament incident to trauma from occlusion

Abstract The experiments were performed in 13 dogs; nine of the animals had initially a healthy periodontium and four had experimental periodontitis. Trauma from occlusion was created in all dogs according to a technique described previously. The dogs were sacrificed after 7, 14, 30 and 180 days of the experiment. Prior to sacrifice colloidal carbon was injected intravenously. The degree of vascular labelling and leucocyte infiltration as well as osteoclastic activity and the size of the marginal periodontal ligament were assessed in biopsy sections. The findings showed that dogs with a healthy periodontal lesion (Group A) differed in their reactions to a jiggling type of occlusal trauma when compared to dogs with an established periodontal lesion (Group B). Whereas the periodontal ligament in Group A had become adapted to the altered occlusion by the end of 6 months of experiment, that of Group B still showed increased vascular leakage, leucocyte migration and osteoclastic activity.     

Microvascular changes in cheek-pouch wounds of oophorectomized hamsters following intramuscular injections of female sex hormones

The increased degree of gingivitis during pregnancy may be ascribed to both the influence of bacterial plaque and the action of sex hormones on the microvascular system. The present investigation was undertaken to elucidate the mechanism behind the changes in vascular structure and function in healthy and in slightly inflamed tissues following an increased blood concentration of estrogens, progesterone and chorionic gonadotropin. The cheek-pouch of oophorectomized female hamsters constituted the experimental model. The animals were oophorectomized 7 days prior to the start of the hormone experiments. A micro-wound was produced surgically in the cheek-pouch to leave a defect area with a slightly damaged vascular bed and a surrounding tissue with unaffected circulation as observed by vital microscopy. Irrigation with Tyrode's solution for 10–15 minutes reversed the inflammatory changes in the defect area. A hormone solution (0.2 ml of 5 mg /ml Stilbol^R or progesterone^R or 0.2 ml of 1,500 I.U./ml Gonadex^R) was injected intramuscularly in the hamster's hind leg either once (short term experiments) or daily during a five day period (long term experiments). Estrogen and chorionic gonadotropin caused only minor vascular changes. When progesterone was added to the circulating blood via the hind leg muscle, the resistance of the wound tissue seemed to be lowered and acute inflammation developed in the defect area. The surrounding tissue was unaffected. The symptoms of Inflammation in the wound were more severe than immediately after the surgical procedure as judged by the degree of swelling of the endothelium lining the veins, the number of leucocytes adhering to the vessel walls and the number of micro-thrombi. The findings are discussed in the light of present knowledge of the effects of female sex hormones on intra vascular and perivascular cell structure and function.     

Mutational analysis of candidate genes in 24 amelogenesis imperfecta families

Amelogenesis imperfecta (AI) is a heterogeneous group of inherited defects in dental enamel formation. The malformed enamel can be unusually thin, soft, rough and stained. The strict definition of AI includes only those cases where enamel defects occur in the absence of other symptoms. Currently, there are seven candidate genes for AI: amelogenin, enamelin, ameloblastin, tuftelin, distal-less homeobox 3, enamelysin, and kallikrein 4. To identify sequence variations in AI candidate genes in patients with isolated enamel defects, and to deduce the likely effect of each sequence variation on protein expression and structure, families with isolated enamel defects were recruited. The coding exons and nearby intron sequences were amplified for each of the AI candidate genes by using genomic DNA from the proband as template. The amplification products for the proband were sequenced. Then, other family members were tested to determine their genotype with respect to each sequence variation. All subjects received an oral examination, and intraoral photographs and dental radiographs were obtained. Out of 24 families with isolated enamel defects, only six disease-causing mutations were identified in the AI candidate genes. This finding suggests that many additional genes potentially contribute to the etiology of AI.     

Re-osseointegration after treatment of peri-implantitis at different implant surfaces

Peri-implantitis is a condition that includes soft tissue inflammation and rapid loss of bone. Treatment of peri-implantitis includes both antimicrobial and bone augmenting methods. The question of whether true re-osseointegration may occur following treatment of peri-implantitis is controversial. The aim of this study was to investigate whether the character of the implant surface was of importance for the occurrence of re-osseointegration following treatment of peri-implantitis. Four beagle dogs were used. The mandibular premolars were extracted. After 12 months, 3 ITI(R) solid screw dental implants were placed in each side of the mandible. In the left side, implants with a turned surface (Turned sites) were used, while in the right side implants with a SLA surface (SLA sites) were placed. After 3 months of healing, peri-implantitis was induced by ligature placement and plaque accumulation. When about 50% of the initial bone support was lost, the ligatures were removed. Five weeks later, treatment was initiated. Each animal received tablets of Amoxicillin and Metronidazole for a period of 17 days. Three days after the start of the antibiotic regimen, one implant site (experimental site) in each quadrant was exposed to local therapy. Following flap elevation, the exposed titanium surface was cleaned with the use of cotton pellets soaked in saline. The implants were submerged. Six months later, biopsies were obtained. Treatment resulted in a 72% bone fill of the bone defects at Turned sites and 76% at SLA sites. The amount of re-osseointegration was 22% at Turned sites and 84% at SLA sites. A treatment regimen that included (i) systemic administration of antibiotics combined with (ii) granulation tissue removal and implant surface cleaning resulted in resolution of peri-implantitis and bone fill in adjacent bone defects. Further, while substantial "re-osseointegration" occurred to an implant with a rough surface (SLA), bone growth on a previously exposed smooth surface (Turned) was minimal.