Thickness of posterior palatal masticatory mucosa: the use of computerized tomography

BACKGROUND: Periodontal plastic surgery is used to fulfill the esthetic and functional demands of patients. The palatal masticatory mucosa is the main donor site for connective tissue, and the thickness of the graft tissue obtained is an important factor for the success of this technique. The aim of this study was to measure the thickness of masticatory mucosa in the posterior palatal area using computerized tomography (CT). METHODS: The thickness measurements were performed on the images of 100 adult subjects who underwent CT on the maxilla for implant surgery. Twenty-four standard measurement points were defined in the hard palate according to the gingival margin and the middle palatal suture. The radiographic measurements were used after calibration. The data were analyzed to determine the differences in the mucosal thickness according to gender, age, tooth position, and depth of the palatal vault. RESULTS: The overall mean thickness of the palatal masticatory mucosa was 3.83 +/- 0.58 mm (range: 2.29 to 6.25 mm). Females had significantly thinner mean masticatory mucosa (3.66 +/- 0.52 mm) than males (3.95 +/- 0.60 mm) (P <0.0001). The thickness of the palatal masticatory mucosa increased with age. The mean thickness according to tooth site was 3.46 mm (maxillary canine), 3.66 mm (first premolar), 3.81 mm (second premolar), 3.13 mm (first molar), 3.31 mm (the base of the interproximal papilla of the first and second molars), and 3.39 mm (second molar). There was an overall increase in the thickness of the palatal masticatory mucosa as the distance from the gingival margin to the middle palatine suture increased, with the exception of the Ca-d (a point at 12 mm from the gingival margin of the canine) region. There was no significant difference in the thickness of the palatal masticatory mucosa between the groups with high or low palatal vaults. CONCLUSIONS: The palatal masticatory mucosa thickness increased from the canine to premolar region but decreased at the first molar region and increased again in the second molar region, with the thinnest area at the first molar region and the thickest at the second premolar region. The canine to premolar region seems to be the most appropriate donor site that contains a uniformly thick mucosa. CT can be considered an alternative method for the measurement of palatal soft tissue thickness.     

The effects of an immediately pre-surgical chlorhexidine oral rinse on the bacterial contaminants of bone debris collected during dental implant surgery

Dental implant surgery produces bone debris that can be used in the "simultaneous augmentation" technique. Although this debris is contaminated with oral bacteria, a stringent aspiration protocol has been shown to reduce the levels of contamination. Chlorhexidine mouthrinse is a well-proven antibacterial rinse that has been shown to reduce infectious complications associated with dental implants. This study examined the effect of pre-operative rinsing with a 0.1% chlorhexidine digluconate mouthrinse on the bacterial contaminants present in collected bone debris bone (CBD). Twenty partially edentate patients were randomly allocated into equal groups and underwent bone collection using the Frios Bone Collector (FBC) during the insertion of two dental implants. In group T a pre-operative chlorhexidine rinse was used, whilst in group C sterile water was used. For both groups, a stringent bone collection protocol was used. Bone samples were immediately transported for microbial analysis. Colonial and microscopic morphology, gaseous requirements and identification kits were utilised for identification of the isolated microbes. Thirty-nine species were identified including a number associated with disease, in particular Actinomyces odontolyticus, Clostridium bifermentans, Prevotella intermedia, and Propionibacterium propionicum. Samples from group T (chlorhexidine mouthrinse) yielded significantly fewer organisms (P < 0.001) than in group C (sterile water mouthrinse). Gram-positive cocci dominated the isolates from both groups. It is concluded that if bone debris is to be used for the purpose of immediate simultaneous augmentation, a preoperative chlorhexidine mouthrinse should be utilised in conjunction with a stringent aspiration protocol to reduce further the bacterial contamination of CBD.     

Combined effect of zinc ions and cationic antibacterial agents on intraoral volatile sulphur compounds (VSC)

OBJECTIVE: Volatile sulphur compounds (VSC) are major components of oral malodour. As both zinc ions and cationic antibacterial agents inhibit the formation of oral VSC, this study aimed to determine whether these agents combined have synergistic anti-VSC actions. METHODS: Baseline oral VSC measurements of mouth air from 10 volunteers following cysteine rinsing (6mM, pH 7.2) were obtained using gas chromatography (GC). Subjects rinsed for 1 min with 10ml of the test solutions, 0.3% zinc acetate (Zn), 0.025% chlorhexidine (CHX), 0.025% cetyl pyridinium (CPC), and the combinations Zn+CHX and Zn+CPC. Cysteine rinses were repeated at 1h, 2h and 3h and VSC measurements recorded. Three subjects rinsed with the Zn+CHX combination and fasted for 9h, undergoing cysteine rinses and VSC measurements at 3h intervals. 10 microl of the test solutions were also added to 1ml aliquots of human whole saliva (n=8). Following incubation at 37 degrees C for 24h VSC levels in the saliva headspace were measured by GC. Inhibition of VSC formation and the fractional inhibitory index indicating synergy were calculated. RESULTS: Zn+CHX mouthrinse had a synergistic anti-VSC effect, and was effective for at least 9h. Zn+CPC mouthrinse was less effective. Both combinations showed a synergistic inhibiting effect in-vitro. CONCLUSIONS: Synergy between Zn and the antibacterial agents confirms different mechanisms of operation.     

Recognition and phagocytosis of multiple periodontopathogenic bacteria by anti-Porphyromonas gingivalis heat-shock protein 60 antisera

The present study has been performed to evaluate Porphyromonas gingivalis heat shock protein (HSP) 60 as a candidate vaccine to protect against multiple putative periodontopathic bacteria. Mouse anti-P. gingivalis HSP antisera demonstrated the elevated IgG antibody titers against the multiple bacteria tested and cross-reacted with heat-induced bacterial proteins of the target bacteria. The antisera also demonstrated a significantly higher opsonophagocytosis function against all the target bacteria than the control sera (P<0.01). We concluded that P. gingivalis HSP 60 could potentially be developed as a vaccine against multiple periodontopathic bacteria.     

Gingival fluid IL-1 and IL-6 levels in refractory periodontitis

Abstract Selected gingival bacteria and cytokine profiles associated with patients who did not respond to conventional periodontal therapy (refractory) were evaluated. 10 subjects with a high incidence of post-active treatment clinical attachment loss (>2% sites/year lost ≥ 3 mm) were compared to 10 age-, race-, and supragingival plaque-matched patients with low post-treatment clinical attachment loss (<0.5% sites/year) relative to the following parameters at 2 sites/patient with the deepest probing depths: (1) presence of 3 selected periodontal pathogens (Actinobacillus antinomycetemcomitans, Porphyromonas gingivalis. Eikenella corrodens) in subgingival plaque as determined by selective culturing, and (2) gingival crevicular fluid (GCF) levels of 3 cytokines associated with bone resorption (IL-1 alpha, IL-1 beta, IL-6) as determined by two-site ELISA. Results indicated no significant differences in any clinical measurement (except incidence of clinical attachment loss), in the presence of any bacterial pathogen, or in GCF cytokine levels between refractory subject sites versus stable subject sites. However, when sites producing the greatest total GCF cytokine/patient were compared, sites from refractory patients produced significantly more IL-6 (30.1 ± 4.0 versus 15.4 ± 2.8 nM, p<0.01). The subgingival presence of each of the 3 bacterial pathogens was associated with elevated GCF IL-1 concentrations. These data suggest that gingival IL-1 and IL-6 production is different in response to local and systemic factors associated with periodontitis, and that IL-6 may play a role in the identification and mechanisms of refractory periodontitis.     

In vivo evaluation of the biocompatibility of implanted biomaterials: morphology of the implant-tissue interactions

Electron microscopic observations were made from tissues apposing titanium and ceramic root form and blade implants. The tissue was serially sectioned from the most coronal epithelium, through the gingival connective tissue, to the osseous support tissues, and directly to the most apical tissue support. Of the thousands of sections analyzed for each implant, 500 micrographs were routinely viewed for each of the implants analyzed by this study. Of the 120 total implants placed in 30 adult dogs, 60 were used for electron microscopy. Osseointegrated implants were often apposed by a mineralized matrix of collagenous fibers. The dense mineralized collagen matrix was often separated from the implant by only a ruthenium positive electron dense deposit 20 to 50 nanometers thick. Areas of the same implant were also apposed by an unmineralized collagen fiber stroma, which ranged in thickness, that contained osteoblasts. Interaction of the osteoblasts and the unmineralized collagen fibers resulted in the mineralization events of osteogenesis. Also apposing other areas of the same integrated implants were lacunar areas containing osteoclasts and vessels. These zones were similar to Howship's Lacunae. These results demonstrated that a normal homeostasis of catabolic osteoclastic activity and metabolic osteoblastic activity resulted in a dynamic implant-tissue interface. This biocompatible and dynamic support complex provides a construct for the long-term clinical serviceability of osseointegrated implants.     

Contemporary management of lateral root perforation diagnosed with the aid of dental computed tomography

Lateral root perforation unnoticed during post-space preparation, and followed by post cementation, can subsequently be challenging to diagnose in the labio-lingual plane due to the two-dimensional nature of conventional radiography. This paper demonstrates the application of a recently developed three-dimensional imaging system, cone beam computed tomography, in the diagnosis of iatrogenic root perforation. A clinical case is reported where labial post perforation in a maxillary central incisor occurring 15 years previously presented with a sinus tract and radiolucent lesion. Non-surgical retreatment and perforation repair using mineral trioxide aggregate was performed with the aid of an operating microscope. The sinus tract resolved with radiographic evidence of healing at 1-year recall.     

A histochemical study of the effects of high doses of sodium fluoride on dipeptidyl peptidase II activity in the rat incisor ameloblast

Female Wistar rats, 3 weeks old, were given sodium fluoride in saline solution (isotonic) by intraperitoneal injection at a dose of either 0, 10 or 20 mg per kg body weight. This treatment was given 9 times over 4.5 days. After fixation by perfusion and demineralization in neutral EDTA, hemi-mandibles were sectioned in a cryostat. Sections were stained for dipeptidyl peptidase II activity, using the specific substrate Lys-Ala-MNA and the coupler Fast Blue B for histochemical localization. Staining indicative of dipeptidyl peptidase II was found in the enamel organ of the incisor, particularly in cells of the stratum intermedium and in both secretory and maturation ameloblasts. This staining was markedly reduced in ameloblasts of rats given either 10 or 20 mg sodium fluoride per kg body weight.     

Predictors of initial stability of orthodontic miniscrew implants

The purpose of this retrospective study was to elucidate potential confounding factors affecting initial stability of miniscrews inserted to enhance orthodontic anchorage. Four hundred and seven miniscrews inserted in 168 patients treated by 17 orthodontic residents were analysed in a consecutive chart review. The outcome variable was the stability of the miniscrew, measured as a dichotomous variable, 0 if the miniscrew loosened during a 1 week period after insertion to the time of orthodontic force application and a value of 1 otherwise. Potential confounding variables examined were gender, age, jaw, insertion site, tissue type, length and diameter of the miniscrew, and number of previous insertions. Generalized estimating equations (GEE) methods were used to estimate the influence of each factor on stability for the correlated binary outcomes of each patient. A weighted analysis for the GEE approach was also performed for the convergence calculation of the estimation procedure due to a value of 0 in one of the cells. Crude odds ratio (cOR) and adjusted odds ratio (aOR) and their 95 per cent confidence intervals (CI) were calculated for this purpose. The overall success rate after 1 week was 93.1 per cent (379/407). The screws inserted by more experienced clinicians (more than 20 miniscrews) were found to have approximately a 3.6-fold higher success rate of initial stability compared with those inserted by less experienced clinicians after adjusting for the insertion site (aOR = 3.63, P = 0.015). The results of the present study suggest that the initial stability depends on insertion site and clinician experience.     

The association of osteoprotegerin gene polymorphisms with periodontitis

Background:  It has been demonstrated that genetic variation accounts for approximately half of the variance in periodontitis. The reported association of polymorphisms in the osteoprotegerin (OPG) gene with osteoporosis suggests that the OPG gene may also influence the genetic risk for periodontitis.
Subjects and methods:  We investigated the distribution of OPG gene polymorphisms in 49 patients with aggressive ( n  =   14) or chronic ( n  =   35) periodontitis and 49 control subjects without periodontitis, using polymerase chain reaction (PCR)–restriction fragment length polymorphism and PCR–single strand conformation polymorphism followed by direct sequencing.
Results:  A total of seven known polymorphisms and one new mutation, G373A, were identified. The T950 and G1181 alleles were more common in patients with periodontitis ( P  =   0.028 and P  =   0.047, respectively) than in control subjects. Especially, G1181 allele was associated with patients with aggressive periodontitis.
Conclusion:  The TG haplotype of T950C and G1181C polymorphisms in the OPG gene may be useful genetic markers for the prediction of periodontitis. Further studies in a larger population are required to determine whether these alleles directly contribute to periodontitis susceptibility.