Ron Wilson

The prevalence of tooth wear in a cluster sample of adolescent schoolchildren and its relationship with potential explanatory factors

Objective: To assess the prevalence of tooth wear in adolescents and its relationship with diet, saliva and gastro-oesophageal reflux.Design: Single centre cluster sample epidemiological study.Setting: A school in London in the summer of 1996.Subjects: 11-14-year-old schoolchildren.Main outcome measures: The Smith and Knight tooth wear index (TWI), salivary factors, diet and symptoms of gastro-oesophageal reflux were recorded for all subjects.Results: Results were obtained from 210 subjects. One subject refused to provide a saliva sample and 11 subjects provided insufficient saliva for analysis of buffering power (n = 198). 57% (95% confidence intervals 50.3–63.7%) of subjects had tooth wear on more than ten teeth and a median 12% (interquartile range 6–18%, 95% confidence intervals 8–14%) of surfaces were affected. However, dentine involvement was rare. The median intake of carbonated drinks was 2 cans (interquartile range 1–3) a day. However, there was no correlation with TWI (r = −0.09, P = 0.19). There was no relationship between tooth wear index (TWI) and salivary flow rate (r = −0.02, P = 0.78) or buffering capacity (r = −0.02, P = 0.76). A trend was observed for those with a reported history of regurgitation (n = 27) to have a higher maxillary TWI (median 8, interquartile range 2–13) compared with those who did not (5, 2–9, P = 0.06).Conclusions: Tooth wear is common in adolescents and the relationship with dietary acid, salivary buffering and symptoms of gastro-oesophageal reflux is complex and requires further investigation

Detection of periapical bone defects in human jaws using cone beam computed tomography and intraoral radiography

AIM To compare the diagnostic accuracy of intraoral digital periapical radiography with that of cone beam computed tomography (CBCT) for the detection of artificial periapical bone defects in dry human jaws. METHODOLOGY Small and large artificial periapical lesions were prepared in the periapical region of the distal root of six molar teeth in human mandibles. Scans and radiographs were taken with a charged couple device (CCD) digital radiography system and a CBCT scanner before and after each periapical lesion had been created. Sensitivity, specificity, positive predictive values, negative predictive values and Receiver Operator Characteristic (ROC) curves as well as the reproducibility of each technique were determined. RESULTS The overall sensitivity was 0.248 and 1.0 for intraoral radiography and CBCT respectively, i.e. these techniques correctly identified periapical lesions in 24.8% and 100% of cases, respectively. Both imaging techniques had specificity values of 1.0. The ROC Az values were 0.791 and 1.000 for intraoral radiography and CBCT, respectively. CONCLUSIONS With intraoral radiography, external factors (i.e. anatomical noise and poor irradiation geometry), which are not in the clinicians control, hinder the detection of periapical lesions. CBCT removes these external factors. In addition, it allows the clinician to select the most relevant views of the area of interest resulting in improved detection of the presence and absence of artificial periapical lesions.

Diagnostic accuracy of small volume cone beam computed tomography and intraoral periapical radiography for the detection of simulated external inflammatory root resorption

AIM To compare in an ex vivo model the ability of digital intraoral radiography and cone beam computed tomography (CBCT) to detect simulated external inflammatory root resorption lesions, and to investigate the effect of altering the degree of rotation of the CBCT scanners X-ray source and imaging detector on the ability to detect the same lesions. METHODOLOGY Small and large simulated external inflammatory resorption (EIR) lesions were created on the roots of 10 mandibular incisor teeth from three human mandibles. Small volume CBCT scans with 180° and 360° of X-ray source rotation and periapical radiographs, using a digital photostimulable phosphor plate system, were taken prior to and after the creation of the EIR lesions. The teeth were relocated in their original sockets during imaging. Receiver operator characteristic (ROC) analysis and kappa tests of the reproducibility of the imaging techniques were carried out and sensitivity, specificity, positive and negative predictive values (PPV and NPV) were also determined for each technique. RESULTS The overall area under the ROC curve (Az value) for intraoral radiography was 0.665, compared to Az values of 0.984 and 0.990 for 180° and 360° CBCT, respectively (P<0.001). The sensitivity and specificity of 180° and 360° CBCT were significantly better than intraoral radiography (P<0.001). CBCT, regardless of the degree of rotation, had superior NPVs (P<0.01) and PPVs (P<0.001) to periapical radiography. The intra- and inter-examiner agreement was significantly better for CBCT than it was for intraoral radiography (P<0.001). The ability of small volume CBCT to detect simulated EIR was the same regardless of whether 180° or 360° scans were taken. Examiners were significantly better able to identify the exact location of the artificial resorption lesions with CBCT than they were with periapical radiographs (P<0.001). CONCLUSION CBCT is a reliable and valid method of detecting simulated EIR and performs significantly better than intraoral periapical radiography. Small volume CBCT operating with 360° of rotation of the X-ray source and detector is no better at detecting small, artificially created EIR cavities than the same device operating with 180° of rotation.

Accuracy of measuring the cortical bone thickness adjacent to dental implants using cone beam computed tomography

OBJECTIVE To assess the accuracy of measuring the cortical bone thickness adjacent to dental implants using two cone beam computed tomography (CBCT) systems. MATERIAL AND METHODS Ten 4 x 11 mm Astra Tech implants were placed at varying distances from the cortical bone in two prepared bovine ribs. Both ribs were scanned in a reproducible position using two different CBCT scanners. Ten examiners each carried out four measurements on all 10 implants using the two CBCT systems: vertical distance between the top of the implant and the alveolar crest (IT-AC), and thickness of the cortical bone from the outer surface of the implant threads at 3, 6 and 9 mm from the top of the implant. Ground sections were prepared and bone thickness was measured using a light microscope and a graticule to give a gold standard (GS) measurement. RESULTS The examiners measurements were significantly different between CBCT systems for the vertical and thickness dimensions (P<0.001) while measuring the cortical bone thickness between 0.3 and 3.7 mm. Within that range, i-CAT NG measurements were consistently underestimated in comparison with the GS. Accuitomo 3D60 FPD measurements closely approximated the GS, except when cortical bone thickness was <0.8 mm. The mean percentage errors from the GS at 3, 6 and 9 mm measurement levels were 68%, 28% and 18%, respectively, for i-CAT NG and 23%, 5% and 6%, respectively, for Accuitomo 3D60 FPD. CONCLUSIONS Within the limitations of this study, it was concluded that i-CAT NG (voxel size 0.3) may not produce sufficient resolution of the thin cortical bone adjacent to dental implants and, therefore, the measurements may not be accurate; whereas, Accuitomo 3D60 FPD (voxel size 0.125) may produce better resolution and more accurate measurement of the thin bone.

Comparison of the effect of fluoride and non-fluoride toothpaste on tooth wear in vitro and the influence of enamel fluoride concentration and hardness of enamel

The effect of the presence of fluoride in toothpaste on tooth wear was investigated in extracted human premolar teeth collected from two geographic areas with different fluoride concentrations in the public water supply. Nine teeth from each area were divided bucco-lingually into matched pairs and subjected to a wear regime in vitro. The regime consisted of 5 minutes immersion in 6% citric acid buffered at pH 3.5, followed by 200 cycles of linear tooth-brushing in a slurry of either a fluoride or a non-fluoride toothpaste, the whole process repeated 720 times. Teeth collected from subjects in Birmingham (public water supply fluoridated at 1 ppm) had a higher fluoride concentration in the surface enamel (P < 0.01) and greater hardness (P < 0.001) than teeth collected from subjects in London (non-fluoridated water supply). The results showed that less wear was produced in the presence of the fluoride toothpaste than in the presence of the non-fluoride toothpaste with an otherwise identical formulation (P < 0.001), and that the amount of tooth wear in vitro was not significantly affected by differences in fluoride concentration and hardness of enamel

Laser modulation of angiogenic factor production by T-lymphocytes.

In previous investigations, small variations in the energy densities of low level light therapy (LLLT) were found to produce significant differences in the proliferation of resting T‐lymphocytes in vitro. Pulsing these cells with mitogen in addition to laser therapy produced inhibitory effects regardless of the amplitude of the energy density used. In the current study, the effect of LLLT on the production of angiogenic factor(s) by T‐lymphocytes was investigated in vitro.

The effect of smoking on bone healing: A systematic review

Objectives To review the systemic impact of smoking on bone healing as evidenced within the orthopaedic literature. Methods A protocol was established and studies were sourced from five electronic databases. Screening, data abstraction and quality assessment was conducted by two review authors. Prospective and retrospective clinical studies were included. The primary outcome measures were based on clinical and/or radiological indicators of bone healing. This review specifically focused on non-spinal orthopaedic studies. Results Nine tibia studies and eight other orthopaedic studies were considered for systematic review. Of these 17 studies, 13 concluded that smoking negatively influenced bone healing. Conclusions Smoking has a negative effect on bone healing, in terms of delayed union, nonunion and more complications.

The detection of periapical pathosis using periapical radiography and cone beam computed tomography - Part 1: pre-operative status

AIM Part 1 of this 2 part study aims to compare the prevalence of periapical lesions on individual roots viewed with intraoral (periapical) radiographs and cone-beam computed tomography (CBCT) of teeth treatment planned for endodontic treatment. METHODOLOGY Diagnostic periapical radiographs and CBCT scans were taken of 151 teeth in 132 patients diagnosed with primary endodontic disease. The presence or absence of periapical lesions was assessed by a consensus panel consisting of two calibrated examiners, a consensus agreement was reached if there was any disagreement. The panel viewed the images under standardised conditions. Part 2 will compare the radiographic outcome 1 year after completion of primary root canal treatment. RESULTS Two hundred and seventy-three paired roots were assessed with both radiological systems, periapical lesions were present in 55 (20%) and absent in 218 (80%) roots assessed with periapical radiographs. When the same 273 sets of roots were assessed with CBCT, lesions were present in 130 (48%) and absent in 143 (52%) roots. Seventy-five additional roots were detected with CBCT. CONCLUSION The limitations of periapical radiographs which may hinder the detection of periapical lesions are overcome with CBCT. This results in firstly, more roots being assessed, and secondly, more periapical lesions being detected with CBCT.

The effect of restorative materials on the wear of human enamel

The wear of human dental enamel against amalgam, Concise composite, SR-Isosit Inlay/Onlay composite, Vitadur-N glazed porcelain, unglazed IPS Empress ceramic, and enamel (control) was investigated by use of a modified stress cycling machine. Testing was carried out in water and in citric acid (pH 4) and the enamel-material couples were subjected to 25,000 cycles of wear with a maximum load of 40 N. Tooth profile reduction was measured at baseline and at 5000 cyclic intervals with a computer image analysis program. The depth of the wear scars on material specimens was analyzed with a profilometer. All materials produced increased enamel wear in acid. Vitadur-N glazed porcelain was found to be the most destructive to human dental enamel, and this was closely followed by Empress and enamel.

Prevalence of Clinically Undetected and Untreated Molar Occlusal Dentine Caries in Adolescents on the Isle of Wight

The prevalence of clinically undetected occlusal dentine caries was determined in a group of adolescents living on the Isle of Wight by comparing data from clinical and radiographic examinations carried out in 1987. 6.3% of maxillary molars and 12.9% of mandibular molars which had been designated as clinically sound showed dentine caries on radiographs. Comparison of the radiographic data from 1975 and 1987 showed that there were more sound and fewer filled occlusal surfaces in 1987, but more primary occlusal caries. Approximately 50% of subjects examined in both 1975 and 1987 had at least one molar tooth with primary and/or secondary caries in dentine on radiograph.