Biologic and mechanical stability of single-tooth implants: 4- to 7-year follow-up

Background: Single‐tooth implants have been reported to achieve a high level of surgical and prosthetic success. However, close inspection of the literature reveals a paucity of data on the follow‐up of single‐tooth implants in function for 5 years or more. Since unsplinted implants may be considered to be subject to greater functional stresses, there is a need to report on the long‐term biologic and mechanical integrity of such implant‐supported restorations. Purpose: To report on the long‐term follow‐up of single‐tooth implants, restored and in function for 4 to 7 years. Materials and Methods: Twenty‐seven Astra Tech single‐tooth implants were subject to a clinical audit to evaluate implant and prosthetic success as well as response of both hard and soft tissues over a 1‐ to 4‐year follow‐up. This current report presents data on the biologic and mechanical integrity of 23 of these single‐tooth implants, which have been in function for up to 7 years (mean, 63 mo). Data are provided with respect to implant survival, maintenance of marginal bone levels, soft‐tissue health, and the recording of any adverse events, including prosthetic complications. Results: Only 14 implants in 13 patients were available for review, with no failures for this group of implants. One patient from the original group, who was lost to follow‐up, was known to have suffered an implant failure. Furthermore, in accordance with established criteria, the remaining 13 implants that are not included in this report must at this time also be considered as potential failures. As such, the best‐case scenario would be a 95.6% success rate for the 23 implants included in this review and the worst‐case scenario would be a 60.8% success rate. Mean marginal bone loss measured 0.49 mm mesially and 0.76 mm distally, with a frequency of bone loss of 50%. Soft tissues were clinically healthy. There were few adverse events, with only one case of abutment screw loosening, detected at the 6‐year review. In addition, crown decementation was recorded three times in two patients. Conclusions: It can be concluded that the Astra Tech single‐tooth implant can achieve long‐term biologic and mechanical stability when used to restore single missing teeth, over the long‐term.     

Morphological variation in the tyrosine receptor kinase A-immunoreactive periodontal ligament epithelium of developing and mature rats

Tyrosine receptor kinase A (trkA) is the high-affinity receptor for nerve growth factor. It has been found in several non-neuronal cell types, indicating biological roles independent of neural function, as well as in the nervous system. An initial study demonstrated that an antibody to the full extracellular domain did not label periodontal ligament epithelium (PLE; also known as epithelial rests of Malassez), but that another antibody which recognises a truncated 41-kDa form of trkA did label PLE. Thus, truncated trkA-immunoreactive (-IR) PLE was further investigated here in developing molars of young rats, and in its mature form in adult rat molars, for its reaction to moderate or deep molar injuries, and for its appearance along the continuously erupting incisors of mature rats. In some of the adult rat molars we also analysed the association of nerve fibres with PLE using antibodies for p75 neurotrophin receptor or peripherin. Rat jaws were fixed with 4% formaldehyde and demineralised, and bound antibody was detected with avidin-biotin-peroxidase and diaminobenzidine or fluorescence procedures. Light microscopy showed great variation in the appearance of trkA-IR PLE and considerable morphological changes during the eruption of molars and incisors. By electron microscopy it was shown that trkA-IR was not uniformly distributed in PLE cells but rather was concentrated in the peripheral zones of each cell cluster. Tooth injury did not influence the form or occurrence of PLE unless there was specific destruction of a ligament region. Qualitative analyses of nerve fibres showed that they only rarely innervated PLE in adult rats, indicating that the truncated receptor has non-neuronal functions in this epithelium. These results suggest that neurotrophin growth factors, acting via truncated trkA receptors, affect the interactions between PLE cells and the periodontal ligament, with fewer PLE interactions with nerves. Furthermore, the expression of these receptors on PLE supports the possibility that these cells are active during tooth development and eruption rather than being merely passive remnants of the degenerating tooth sheath. The similar trkA-IR of PLE and junctional epithelium, as well as their structural association, suggests interactions between these two epithelia.     

Multiple hyperdontia: Report of an unusual case

Supernumerary teeth are an infrequent developmental anomaly that can appear in any area of the dental arch and can affect any dental organ. Multiple supernumerary teeth, or hyperdontia, is rare in people with no other associated diseases or syndromes. Conditions commonly associated with hyperdontia include cleft lip and palate, trichorhinophalangeal syndrome, cleidocranial dysplasia, and Gardner's syndrome. A black girl, aged 11 years 8 months, came for consultation; radiographs showed 81 teeth: 18 deciduous, 32 permanent, and 31 supernumerary. The main concern initially was to determine whether she was syndromic, and she was referred to a geneticist. G banding analysis showed pericentric inversion of chromosome 9; the chromosome formula was 46, XX, inv (9) (p13q21). Orthodontic treatment for this patient will be a clinical challenge because of the great number of teeth to be extracted and the alterations in the shapes of the teeth. Treatment goals should be established by a multidisciplinary team, where oral surgeon, orthodontist, periodontist, and prosthodontist come together to solve a medical and dental puzzle, eliminating the pieces that do not fit and searching for new ones to obtain an occlusion that will give the patient physiologic conditions of normality and esthetic satisfaction.     

Chemomechanical caries removal in children: an operator's and pediatric patients' responses

BACKGROUND: This study investigated an operator's and pediatric patients' responses to chemo-mechanical caries removal (CMCR) versus the traditional method (TM) of caries removal using a handpiece and a round bur when treating dentinal-depth occlusal lesions with minimal enamel access in primary molars. METHODS: Data were collected from 50 children at baseline and before, during and after caries removal using CMCR or TM. The subjects in the CMCR group were on average younger than the subjects in the TM group and had more deep lesions. RESULTS: The operator rated CMCR as needing more clinical and technical effort and more total effort than TM. He was less satisfied with CMCR than with TM. Subjects in the CMCR group perceived the time needed for treatment as significantly longer than did the subjects in the TM group. Fear of the dentist decreased in subjects in the TM group from before to after the operative appointment, while it increased in subjects in the CMCR group. CONCLUSIONS: The authors found no direct advantage in using CMCR over using TM. CLINICAL IMPLICATIONS: CMCR cannot be recommended as an alternative to TM when treating dentinal depth occlusal lesions with minimal access in primary molars.     

Total viable counts, ATP, and endotoxin levels as potential markers of microbial contamination of dental unit water systems

OBJECTIVES: To determine if either ATP or endotoxin concentrations in water supplied by dental unit water systems (DUWS) correlated with total viable counts (TVC), and therefore could be used as a rapid, chairside measure of levels of microbial contamination. DESIGN: A prospective trial. METHOD: Fifty-seven water samples were taken from the 'triple spray', air rotor and source water supplies from 25 dental units in eight practices. The samples were assayed for endotoxin concentration, total ATP and TVC. A pilot study was performed to assess the relationship between TVC and total cell counts, as determined by flow cytometry. RESULTS: ATP concentrations ranged from 22 to 958 relative light units (RLU) and free endotoxin ranged from 25 to 600 EU ml(-1). TVC varied from not detected to 2.16 x 10(4) CFU ml(-1). The ATP method proved to be a simple and rapid method that could be used at the chairside. However, there was no correlation between ATP or endotoxin concentrations and TVC in DUWS. TVC generally underestimated the total cell count by 50 to 500 fold. CONCLUSION: Half of the water samples from DUWS exceeded recommended levels of TVC. However, ATP and endotoxin concentrations in DUWS water samples did not correlate with these TVC data and therefore could not be recommended as an alternative assay to TVC for measuring bacterial contamination or for monitoring water treatment efficacy.