Development of a treatment outcome standard as a result of a clinical audit of the outcome of fixed appliance therapy undertaken by hospital-based consultant orthodontists in the UK

Bristol's much-publicised cardiac surgery problems and subsequent enquiry(1) have drawn attention to the need for audit of treatment outcomes throughout all hospital specialties. Patient anxiety, government policy and the desire of the professions to re-establish public confidence, have further encouraged changes to the system. For medical and dental specialties, such challenges have already been taken up by the Royal Colleges with the establishment of clinical effectiveness committees. Hospitals have modified their procedures and, for consultants, yearly appraisal is already a reality. The Orthodontic Clinical Effectiveness Working Party of the Royal College of Surgeons of England (now the Clinical Effectiveness Committee of the British Orthodontic Society) set up this audit to measure the outcome of fixed appliance treatment and to establish a benchmark for the standard of treatment to be expected from a consultant orthodontist. This paper describes how the audit was carried out, presents the findings and goes on to discuss some of the wider issues involved in audit, clinical governance and appraisal. The Consultant Orthodontists Group of the British Orthodontic Society funded this audit and the results and data set of dental casts remain their property.     

Analysis of the pattern of maxillofacial fractures in Kaduna, Nigeria

There are considerable differences in the reported worldwide pattern of maxillofacial fractures. In the more developed countries of Europe, violence followed by road crashes are the predominant causes while in the developing world the causative factors are reversed with most being the result of road crashes. Interestingly, recent data indicated a 3:1 male:female ratio worldwide. Between 1991 and 2000, 443 cases of maxillofacial fractures were seen at the Maxillofacial Unit, Ahmadu Bello University Teaching Hospital, Kaduna, Nigeria. Road crashes were responsible for 246 cases (56%) followed by falls, 24% (n=108). In a previous report from this centre in 1980, 241 fractures were seen each year, so our lower rate of 44 cases a year is because the number of centres for the treatment of such injuries in Nigeria has increased. There has also been a fourfold increase in the number of women with facial fractures in this largely Moslem population, which reflects their greater exposure during the past 20 years. More patients were seen with mandibular than middle-third fractures, because more of the latter died. This shows that while more centres for treatment are available for patients with maxillofacial trauma, the lack of enforcement of legislation on the use of seat belts, drunken driving and inadequate emergency medical care have continued to cause considerable mortality and morbidity from these injuries in Nigeria. It is also difficult to compare data among centres because of inconsistent terminology.     

Differences in mouse strain influence leukocyte and immunoglobulin phenotype response to Porphyromonas gingivalis

This study examined the nature of the infiltrating cells in Porphyromonas gingivalis-induced lesions and immunoglobulins in the serum samples of BALB/c (H-2^d), C57BL6 (H-2^b), DBA/2J (H-2^d) and CBA/CaH (H-2^k) mice. Mice were immunized intraperitoneally with P. gingivalis outer membrane antigens or sham-immunized with phosphate-buffered saline followed by subcutaneous challenge with live organisms 1 week after the final immunization. The resulting skin abscesses were excised 7 days later, cryostat sections cut and an immunoperoxidase method used to detect the presence of CD4⁺ and CD8⁺ T-cell subsets, CD14⁺ macrophages and CD19⁺ B cells. Peroxidase positive neutrophils and IgG1- and IgG2a-producing plasma cells were also identified. Anti P. gingivalis IgG1 and IgG2a subclass antibodies were determined in serum obtained by cardiac puncture. Very few CD8⁺ T cells and CD19⁺ B cells were found in any of the lesions. The percentages of CD4⁺ cells, CD14⁺ cells and neutrophils were similar in lesions of immunized BALB/c and C57BL6 mice, with a trend towards a higher percentage of CD14⁺ cells in sham-immunized mice. The percentage of CD14⁺ cells was higher than that of CD4⁺ cells in immunized compared with sham-immunized DBA/2J mice. The percentages of CD4⁺ and CD14⁺ cells predominated in immunized CBA/CaH mice and CD4⁺ cells in sham-immunized CBA/CaH mice. The percentage of neutrophils in immunized CBA/CaH mice was significantly lower than that of CD14⁺ cells and CD4⁺ cells in sham-immunized mice. IgG1⁺ plasma cells were more dominant than IgG2a⁺ cells in immunized BALB/c, C57BL6 and DBA/2J mice, whereas IgG2a⁺ plasma cells were more obvious in sham-immunized mice. IgG2a⁺ plasma cells were predominant in immunized and sham-immunized CBA/CaH mice. In the serum, specific anti-P. gingivalis IgG2a antibody levels (Th1 response) were higher than IgG1 levels (Th2 response) in sham-immunized CBA/CaH and DBA/2J mice. In immunized BALB/c mice, IgG2a levels were lower than IgG1 levels, while IgG2a levels were higher in immunized C57BL6 mice. In conclusion, this study has shown differences in the proportion of infiltrating leukocytes and in the subclasses of immunoglobulin produced locally and systemically in response to P. gingivalis in different strains of mice, suggesting a degree of genetic control over the response to P. gingivalis.     

The microflora of the erupting first permanent molar

The relationship between microflora, eruption status and caries status in the first permanent molar of young children was investigated in 177 children aged 6-7 years. A significantly greater proportion of fully erupted teeth were classified as sound and plaque-free compared to partially erupted teeth. Fully erupted teeth yielded greater numbers and proportions of mutans streptococci compared with significantly greater numbers and proportions of Actinomyces israelii in partially erupted teeth. Logistical regression analysis showed significant associations between white spot lesions in partially erupted teeth and increased numbers of Streptococcus oralis, mutans streptococci and Streptococcus salivarius whereas the presence of Actinomyces naeslundii was associated with health. Significantly greater numbers and proportions of S. oralis and S. salivarius were isolated from partially erupted teeth with white spot lesions whereas Streptococcus mutans was isolated in significantly greater numbers and proportions from fully erupted molars with white spots. This study suggests that organisms other than mutans streptococci are associated with caries development in erupting permanent molar teeth.     

Effect of ProRoot MTA mixed with chlorhexidine on apoptosis and cell cycle of fibroblasts and macrophages in vitro

AIM: To compare the percentage of apoptotic cells and the cell cycle profile of fibroblasts and macrophages exposed to either ProRoot mineral trioxide aggregate (MTA) mixed with chlorhexidine (CHX), or exposed to ProRoot MTA mixed with sterile water. METHODOLOGY: Mouse gingival fibroblasts or mouse macrophages were seeded in six-well plates and allowed to attach overnight. Freshly mixed or set (allowed to dry for 24 h) specimens of tooth-coloured (white) ProRoot MTA were prepared with 0.12% CHX gluconate (MTA/CHX) or with sterile water (MTA/H2O). The cells were exposed for 24 h to the MTA specimens, which were placed over permeable membrane inserts to avoid direct contact with the cells. Untreated cells served as controls. Propidium iodide staining followed by flow cytometry was used to evaluate the effects of ProRoot MTA on cell apoptosis and cell cycle. Statistical analyses were performed by one-way anova followed by post-hoc tests with the use of the SigmaStat 2.0 software, and significance was determined at P < or = 0.05. RESULTS: MTA specimens containing CHX induced apoptosis of macrophages and fibroblasts (P < 0.05). In contrast, no change in the proportion of apoptotic cells was observed when sterile water was used to prepare the specimens (P > 0.05). Cell cycle analysis showed that exposure to MTA/CHX decreased the percentage of fibroblasts and macrophages in S phase (DNA synthesis) as compared with exposure to MTA/H2O (P < 0.05). CONCLUSION: This in vitro study demonstrated that the substitution of CHX for sterile water in MTA increases its cytotoxicity. This suggests that the potentially beneficial antimicrobial effect of CHX may be accompanied by an increase in the cytotoxicity of the resulting MTA-based material.     

Marginal adaptation of mineral trioxide aggregate (MTA) compared with amalgam as a root-end filling material: a low-vacuum (LV) versus high-vacuum (HV) SEM study

AIM: To compare the marginal adaptation of mineral trioxide aggregate (MTA) or amalgam root-end fillings in extracted teeth under low-vacuum (LV) versus high-vacuum (HV) scanning electron microscope (SEM) viewing conditions. METHODOLOGY: Root-end fillings were placed in 20 extracted single-rooted maxillary teeth. Ten root ends were filled with MTA and the other 10 root ends were filled with amalgam. Two 1 mm thick transverse sections of each root-end filling were cut 0.50 mm (top) and 1.50 mm (bottom) from the apex. Gap size was recorded at eight fixed points along the dentine-filling material interface on each section when uncoated wet (LV wet (LVW)) and dry under LV (0.3 Torr) in a JEOL JSM-5800 SEM and backscatter emission (LV dry uncoated (LVDU)). The sections were then air-dried, gold-coated and gap size was recorded once again at the fixed points under HV (10(-6) Torr; HV dry coated (HVDC)). Specimen cracking, and the size and extent of the crack were noted. RESULTS: Gap sizes at fixed points were smallest under LVW and largest under HVDC SEM conditions. Gaps were smallest in MTA root-end fillings. A General Linear Models Analysis, with gap size as the dependent variable, showed significant effects for extent of crack in dentine, material and viewing condition (P = 0.0001). CONCLUSIONS: This study showed that MTA produced a superior marginal adaptation to amalgam, and that LVW conditions showed the lowest gap size. Gap size was influenced by the method of SEM viewing. If only HV SEM viewing conditions are used for MTA and amalgam root-end fillings, a correction factor of 3.5 and 2.2, respectively, may be used to enable relative comparisons of gap size to LVW conditions.     

Adhesive resin induces apoptosis and cell-cycle arrest of pulp cells

The application of an adhesive resin near or directly over the pulp was shown to induce pulp inflammation and lack of dentin regeneration. We hypothesize that the absence of dentin bridging is due to adhesive-resin-induced apoptosis of cells responsible for pulp healing and dentin regeneration. Mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), or macrophages (RAW 264.7) were exposed to SingleBond polymerized for 0-40 seconds. Annexin V and propidium iodide assays demonstrated that SingleBond induced apoptosis of MDPC-23, OD-21, and macrophages. The proportion of apoptotic cells was dependent on the degree of adhesive resin polymerization. Adhesive-resin-induced death of pulp cells was associated with activation of the pro-apoptotic cysteine protease Caspase-3. Interestingly, most cells exposed to adhesive resin that did not undergo apoptosis showed cell-cycle arrest. We conclude that an adhesive resin induces apoptosis and cell-cycle arrest of cells involved in the regeneration of the dentin-pulp complex in vitro.     

Evaluation of the position of the hyoid bone in relation to vertical facial development

Evaluation of the position of the hyoid bone in relation to vertical facial development and comparative evaluation of the relation of this position with the dentofacial system was made on 25 patients with hyperdivergent vertical growth, 25 patients with hypodivergent vertical growth, and 25 patients with normal vertical facial development. SN-Go-Gn, Gonion, ANS-PNS/Go-Gn angles and S-Go, N-Me, S-Go/N-Me measurements from lateral cephalometric films were used as identification parameters. Seven horizontal, five vertical and five angular cephalometric measurements were made in order to determine the position of the hyoid bone. SN plane was used as the reference plane. Results were evaluated through "t" test. No significant relation was found between hyoid bone position and gender. When gender distinction was disregarded, and the group with normal facial development was compared with the hyperdivergent group, statistically significant differences were observed for CVT-H distance in horizontal measurements and for H-SN, H-F, H-PD, H-OD distances in vertical measurements. When the group with normal facial development was compared with the hypodivergent group, only the horizontal measurement Pg-H was statistically significant. The hyoid bone location in the hyperdivergent group was in a more of a posterior and superior position. The hyoid bone location in the hypodivergent group was not changed vertically, however, it had more of a posterior placement with the increase of Pg-H distance.     

Image layer characteristics of the PC 1000 (mark II)

The objective of this study was to investigate empirically the image layer characteristics of the PC 1000 Mark II. Radiographs were taken of a lead resolution grid positioned at 1 mm increments along angular intervals of the projected x-ray beam. The receptor was T-Mat G film combined with Lanex Regular Screens. The path of the effective rotation center was determined using a film positioned horizontally at right angles to the slit beam. The vertical magnification factor, horizontal magnification and Distortion Index, corrected for the position of the tomographic layer, were calculated using a reference object placed at various resolution limits of the image layer. The beam projection angle was compared to the average dental arch shape and proximal contact angle. The maximum resolution observed at the central plane of the image layer was 4 lp · mm⁻¹. The image layer width at the 1.5 lp · mm⁻¹ resolution contour varied from 12 mm anteriorly to 41 mm posteriorly. The vertical magnification factor within the image layer showed a linear increase along the beam path from 1.21 to 1.36. The horizontal magnification varied from 1.07 to 1.71, and the Distortion Index from 0.85 to 1.15. The beam projection angulations to the average arch shape ranged from 90° anteriorly to 115° in the premolar segments and 105° in the molar regions. The empirically derived image layer of the PC 1000 Mark II conforms to the shape of the average dental arch and that found using MTF analysis. The spatial resolution attained using a standard receptor is within the acceptable range.