Cultivable microbial flora associated with persistent periapical disease and coronal leakage after root canal treatment: a preliminary study

AIM: To identify the cultivable bacterial flora in root filled teeth with persistent periapical lesions and to locate their distribution within the root canal system using an in vitro sampling protocol. METHODOLOGY: Eight freshly extracted root filled teeth were collected from the Oral and Maxillo-facial Surgery Department, Eastman Dental Hospital. Seven teeth were associated with persistent apical periodontitis and also showed evidence of coronal leakage. Teeth were transferred to an anaerobic chamber immediately after careful extraction and sectioned transversely to give a crown (in all but one case) and two root segments (coronal and apical). Two samples were obtained from each segment, one from dentine and the other from the restoration or gutta-percha (GP) root filling (46 sites in total). The samples were dispersed, serially diluted and cultured on blood agar and fastidious anaerobic agar (with 5% defibrinated horse blood). The primary growth was subcultured to obtain pure isolates, which were identified by routine microbiological techniques and commercial enzyme tests. RESULTS: A total of 252 strains were isolated from all the teeth. Of all the isolates, the most prevalent bacteria were Gram-positive facultative anaerobes 189/252 (75%) with staphylococci (48/252, 19%), streptococci (44/252, 17%), enterococci (20/252, 8%) and Actinomyces species (20/252, 8%) being found in most of the teeth (6/8, 6/8, 5/8, 5/8 and 7/8, respectively). Of the obligate anaerobes (17%), peptostreptococci (7%) were also present in most teeth (7/8). A statistical association between bacterial flora and site (crown/coronal/apical) or surface (dental/GP/restoration) could not be shown. CONCLUSIONS: The predominant group of bacteria in root filled teeth with persistent apical periodontitis and coronal leakage was Gram-positive facultative anaerobes of which staphylococci followed by streptococci and enterococci were the most prevalent.     

"Moebius syndrome": a case report

Moebius syndrome is an extremely rare disorder characterized by a lifetime facial paralysis, involving sixth and seventh cranial nerves with malformations of orofacial structures and the limbs. In this case, an 8 year old girl with Moebius syndrome is presented, clinical findings are described and management aspects are discussed. Early dental evaluation and parental counselling as a part of preventive dental regimen can go a long way in providing complete psychosocial rehabilitation for such physically disabled children.     

Dealloying and electroformation in high-Pd dental alloys.

OBJECTIVE: The corrosion of high-Pd dental alloys, depending on their composition, is postulated to be associated with dealloying and electroformation. The aim of this study was to obtain additional information to support these postulations. METHODS: The corrosion characteristics of two commercial high-Pd alloys, Naturelle (79Pd-10Cu-2Au-9Ga wt%) and Rx 91 (54Pd-37Ag-9Sn), and their elemental components were evaluated in a phosphated buffer saline (PBS) solution. Indium, a common element in high-Pd alloys, was also included. The corrosion characteristics measured for each material were the 24 h open circuit potential (OCP) and the potentiodynamic anodic polarization curve. Additionally, the surface composition of the two alloys, before and after immersion corrosion in PBS for 2 months, was analyzed by X-ray photo electron spectroscopy (XPS). RESULTS: Of the pure metals, Ga had the most electroactive OCP followed in order by In, Sn, Cu, Ag, Au, and Pd. The anodic polarization data showed all base metals to be unstable in PBS. The electroformation of AgCl was evidenced in the polarization curve of pure Ag. Both electrochemical characteristics of the PdCu-based alloy were very similar to that of pure Pd. The PdAg-based alloy displayed corrosion behavior resembling that of Ag. XPS data showed that the corrosion of the PdCu-based alloy was associated with a decrease in surface content of Cu and Ga but an increase in Pd and Au. The PdAg-based alloy surface during corrosion showed a decrease in Sn, an increase in Ag, and an unaltered Pd content. The behavior of the PdCu-based alloy is attributed to the operation of a galvanic interaction that causes dissolution of base metals and surface enrichment with primarily Pd. Dealloying, Ag-enrichment, and AgCl formation are thought to have contributed to the observed behavior of the PdAg-based alloy. These mechanisms are consistent with data from published ion release studies. SIGNIFICANCE: The allergenic potential of any Pd alloy is dependent on its propensity to develop a Pd-rich surface and thus release Pd+2 ions. The present study, though limited, has shown that electrochemical characteristics, namely OCP and polarization curves, can be used to identify such alloys. Further studies are warranted to evaluate the widespread applicability of these characteristics in distinguishing between Pd alloys that are biologically safe and those that are not.     

Effects of low-energy CO2 laser irradiation and the organic matrix on inhibition of enamel demineralization

In the past two decades, accumulated evidence has clearly demonstrated the inhibitory effects of laser irradiation on enamel demineralization, but the exact mechanisms of these effects remain unclear. The purpose of this study was to investigate the effects of low-energy CO2 laser irradiation on demineralization of both normal human enamel and human enamel with its organic matrix removed. Twenty-four human molars were collected, cleaned, and cut into two halves. One half of each tooth was randomly selected and its lipid and protein content extracted. The other half of each tooth was used as the matched control. Each tooth half had two window areas. All the left windows were treated with a low-energy laser irradiation, whereas the right windows served as the non-laser controls. After caries-like lesion formation in a pH-cycling environment, microradiographs of tooth sections were taken for quantification of demineralization. The mean mineral losses (with standard deviation) of the enamel control, the lased enamel, the non-organic enamel control, and the lased non-organic enamel subgroups were 3955 (1191), 52(49), 4565(1311), and 1191 (940), respectively. A factorial ANOVA showed significant effects of laser irradiation (p = 0.0001), organic matrix (p = 0.0125), and the laser-organic matrix interaction (p = 0.0377). The laser irradiation resulted in a greater than 98% reduction in mineral loss, but the laser effect dropped to about 70% when the organic matrix in the enamel was removed. The results suggest that clinically applicable CO2 laser irradiation may cause an almost complete inhibition of enamel demineralization.     

Analysis of lateral tooth movement during forced orthodontic eruption

STATEMENT OF PROBLEM: Forced eruption is a prosthodontic procedure that enables the treatment of otherwise problematic restorative conditions. During the vertical orthodontic movement, the root may be moved laterally, affecting the position of a tooth in the arch. PURPOSE: This study quantified the degree of lateral movement possible during the eruptive procedure and addressed the significance of this movement from a theoretical and clinical standpoint. MATERIAL AND METHODS: A patient treatment, which demonstrated the movement in a single direction on the buccolingual axis, was isolated. On the basis of this theoretical model, a clinically relevant model was developed: A "worst-case" situation for each posterior tooth was calculated, from which clinical conclusions may be derived. RESULTS:. In a given extrusion angle of 30 degrees, a lateral movement/shift of 0.58 mm resulted per 1 mm of eruption distance. The lateral movement for every millimeter of eruption and the maximum extrusion angle for each of the maxillary and mandibular posterior teeth were calculated. CONCLUSION: The lateral movement that accompanies the forced eruption procedure may compromise or be used to esthetically enhance prosthodontic treatment.     

Use of an existing post to rerestore an endodontically treated tooth with a new post-and-core complex and crown: a case report.

Replacement of a post-and-core restoration that has failed because of caries or fracture presents a restorative challenge to the general dentist. This case report describes a new technique that enables the utilization of an unremovable preexisting post in the fabrication of a new post-and-core complex. This complex served as a foundation for a restoration that restored form and function to the patient's dentition.     

Complete congenital bony syngnathia in a case of oromandibular limb hypogenesis syndrome

Congenital fusion of the maxilla and mandible (syngnathia) is rare and can present in a wide range of severity from single mucosal bands (synechiae) to complete bony fusion (synostosis). Congenital synostosis of the mandible and maxilla is even less common than synechiae, with only 19 cases reported in the literature. Most of them have presented as an incomplete, unilateral fusion. Only three of the reported cases showed more extensive but still incomplete, intermaxillary bony fusion. We present a case of complete bony fusion of the maxilla and mandible associated with a cleft palate, hypoglossia, micrognathia, unilateral choanal atresia, and limb abnormalities as a feature of oromandibular limb hypogenesis syndrome. Details of operative management are presented.     

Patient and dentist satisfaction with a computerized local anesthetic injection system

The fear of dental injections is common among dental patients. Many approaches to reducing this fear of injections and improving local dental anesthesia delivery have been tried in the last few decades. One approach is the use of a computerized or electronic local anesthetic system. This study surveyed dentist and patient satisfaction when local dental anesthesia was delivered with a computerized delivery system. The patients and dentists were both satisfied with the effectiveness of the anesthesia. The patients were satisfied with the level of comfort with the injections. This was particularly true when compared to their previous anesthetic injections. Although the dentists were very satisfied with the performance of the anesthetic delivery system and the anesthesia itself, they did not, in general, choose to use the system in everyday practice. Possible reasons for this within the context of this study are discussed.     

Digital radiography and California third parties

Acceptance of digital radiography is increasing but has not yet progressed to the mainstream. A key factor in widespread use of this advancement is acceptance--both theoretical and technological--by dental health plans for claim submissions. This article details a survey of California third parties to examine their practices, concerns, and plans regarding digital dental radiography.