Crouzonodermoskeletal syndrome

Crouzon craniostenosis [MIM 123500], is identified on the basis of the additional phenotypical manifestations of acanthosis nigricans, vertebral changes and cementomas of the jaws. Choanal atresia and hydrocephalus are other features. The molecular defect in CDSS is a point mutation in the FGFR3 gene on chromosome 4p, whereas, the mutation in the Crouzon syndrome is in the FGFR2 gene at 10q25.3-26. An affected girl aged 2 years presented at the UWC dental genetics unit with a prior diagnosis of Crouzon syndrome. Choanal atresia had necessitated a permanent tracheostomy, and hydrocephalus was managed by a shunt operation. Clinical examination revealed acanthosis nigricans in the axilliary regions, a diagnosis confirmed by a biopsy of the lesion. Eruption of the primary dentition was delayed with only six out of twenty teeth present. Radiographic examination conducted shortly after birth revealed the presence of several tooth buds in both the maxillae and the mandible. The delayed eruption of the teeth will be of significance in future orthodontic and maxillofacial measures for the improvement of the patient's facial Crouzonodermoskeletal syndrome (CDSS) was separated from the classical appearance. Molecular investigations in the girl and her parents are underway. If the specific mutation in FGFR3 is observed, a positive diagnosis of CDSS will be confirmed and the status of her parents and other family members will be determined. On this basis, appropriate genetic management can be offered to the kindred.     

Prevalence of early childhood caries among First Nations children, District of Manitoulin, Ontario

Background. Epidemiological studies of Aboriginal communities in Canada and Native American populations in the United States have reported that early childhood caries (ECC) is highly prevalent. The purpose of this study was to determine the prevalence of ECC and dental caries in the First Nations population of 3‐ and 5‐year‐old children in the District of Manitoulin, Ontario to assist in developing effective dental health promotion strategies. Methods. All 3‐ and 5‐year‐old children in elementary schools and day‐care centres in seven First Nation communities were eligible for the survey examination. Three‐year‐old children at home and 5‐year‐old children attending school off‐reserve in six of the communities were also eligible for epidemiological survey examination of oral health status including caries, gingival and soft tissue conditions. Cases of ECC were defined as children with caries or restorations on two or more primary maxillary incisors or canines or those having a total decayed, missing, filled primary teeth (dmft) score of 4 or greater. Results. A total of 87 children (59% 5 years old, 54% females) were examined. Seventy‐four per cent of children had one or more carious lesions. Forty‐five cases of ECC were found, a prevalence of 52%. The mean dmft score for cases was 7·5 (95% CI 6·5–8·4) and 0·8 (95% CI 0·5–1·1) for non‐cases (P < 0·001). Boys in both age groups were more likely to be affected by ECC than girls. Conclusion. Our results indicate that dental caries and ECC are highly prevalent in this population, with ECC cases having 6.7 more dmft than non‐cases.     

Dynamic viscoelasticity of soft liners and masticatory function

Soft denture liners are used for edentulous patients to cushion functional forces. We hypothesized that the application of soft liners having viscoelastic properties would lead to the most marked improvement in masticatory function. The shear storage modulus (G'), shear loss modulus (G'), and loss tangent (tan delta) were determined for 6 materials by means of a dynamic viscoelastometer. Masticatory function of ten subjects was evaluated by measurements of maximum bite forces and chewing times and frequencies for 2 food samples, and by the use of visual analogue scales. The acrylic materials exhibited viscoelastic behavior, while the silicones exhibited elastic behavior. The improvement in masticatory function compared with hard resin was found to be in the order: acrylic permanent materials > silicone > acrylic temporary materials. The results suggest that the use of materials with higher tan delta and G' provides the most optimum masticatory function for patients requiring the provision of soft liners on their dentures.     

Tissue oxygen tension and blood-flow changes in rat incisor pulp with graded systemic hyperoxia

The role of oxygen in the regulation of the pulpal microcirculation is unknown. This investigation is aimed to measure tissue oxygen tension and blood-flow changes in the pulp of rat lower incisors during graded systemic hyperoxia, and to determine the response of the pulpal vasculature to various oxygen tensions. Twenty-four Sprague-Dawley rats were anaesthetized and artificially ventilated with the appropriate gas mixture. Recessed oxygen-sensitive microelectrodes were used to measure pulpal tissue oxygen tension via a small access cavity filled with saline on the labial surface of the incisor. A laser Doppler flowmeter was used to record pulpal blood-flow. Inspired oxygen was increased stepwise from 20 to 100% in 20% steps. Systemic blood-gas concentrations were measured at each step. Systemic arterial oxygen tension at 100% oxygen ventilation reached 481.2 +/- 30.7% of the baseline at 20% oxygen breathing (n=21). Pulpal tissue oxygen tension did not change significantly whereas pulpal blood-flow fell dose-dependently to 74.6 +/- 5.0% at 100% oxygen ventilation (n=21). Systemic hyperoxia, therefore, induces a significant reduction in pulpal blood-flow whereas pulpal tissue oxygen tension remains relatively stable, indicating an oxygen-dependent local regulatory mechanism.     

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.     

Effect of magnification on locating the MB2 canal in maxillary molars

The purpose of this study was to determine if the surgical operating microscope and/or dental loupes could enhance the practitioner's ability to locate the second mesiobuccal canal (MB2) canal of maxillary molars in an in vivo, clinical setting. The participating endodontists documented 312 cases of root canal therapy on maxillary first and second molars. Participants that used the microscope or dental loupes located the MB2 canal with a frequency of 57.4% and 55.3%, respectively. Those using no magnification located the MB2 canal with a frequency of 18.2%. When no magnification was used, significantly fewer MB2 canals were located based by Chi-square analysis at p < 0.01. There was no significant difference between the use of the microscope and dental loupes in the frequency of locating the MB2 canal. When the maxillary first molars were considered separately, the frequency of MB2 canal detection for the microscope, dental loupes, and no magnification groups was 71.1%, 62.5%, and 17.2%, respectively. The results of this study show that the use of magnification in combined groups leads to a MB2 detection rate approximately three times that of the nonmagnification group and that the use of no magnification results in the location of significantly fewer MB2 canals. Based on these results, more emphasis should be placed on the importance of using magnification for locating the MB2 canal.     

Immunolocalization of urokinase and its receptor in prematurely fused cranial sutures of infants

In cranial sutural samples derived from five children with premature cranial suture fusion we have performed immunostaining for the urokinase plasminogen activator (uPA) and urokinase receptor (uPAR). We have found a strong reactivity for cell- or matrix-bound uPA and uPAR in the sutural connective tissue and associated with the osteoblasts and osteocytes lining the calvarial bone. The sutural tissue itself showed a banding with different intensity of urokinase and uPAR staining concerning connective tissue. It is proposed that the components of the plasminogen activating system are involved in tissue turnover of sutural tissue and in sutural growth.     

Metastatic transitional cell carcinoma of the urinary bladder presenting as a mandibular gingival swelling

Oral cavity metastases mostly originate from the breasts, lungs, or kidneys. Transitional cell carcinoma (TCC), the most frequent malignant tumor of the urinary bladder, rarely metastasizes to the jaws. To the best of our knowledge, only 8 cases of bladder carcinoma have been reported in the English literature to metastasize to the jawbones. A new case of mandibular metastasis of urinary bladder TCC with extension to the gingiva is presented in a 64-year-old white man. The patient was referred for a periodontal infection of the upper right first molar. The clinical examination also showed a gingival swelling located in the lower left premolar region with a hypoasthesia of the left side of the lower lip. The gingival mass was biopsied, and the microscopy showed a mandibular metastatic TCC of the urinary bladder extending to the gingiva. Periodontists should be aware that, although gingival metastases are rare, when they occur they may mimic other local benign pathological conditions.     

Jaw clenching: muscle and joint forces, optimization strategies

Realistic masticatory muscle and temporomandibular joint forces generated during bilateral jaw clenching are largely unknown. To determine which clenching directions load masticatory muscles and temporomandibular joints most heavily, we investigated muscle and joint forces based on feedback-controlled electromyograms of all jaw muscles, lines of action, geometrical data from the skull, and physiological cross-sectional areas acquired from the same individuals. To identify possible motor control strategies, we applied objective functions. The medial pterygoid turned out to be the most heavily loaded muscle for all bite directions. Biting with accentuated horizontal force components provoked the highest loading within the medial and lateral pterygoids. The largest joint forces were also found for these bite directions. Conversely, the lowest joint forces were detected during vertical biting. Additionally, joint forces with a clear posterior orientation were found. Optimization strategies with the elastic energy as objective function revealed the best fit with the calculated results.