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Biomedical subjects

C Longbottom

Publications and source records attributed to C Longbottom.

31 records · Page 2Linked to original sources
PubMed1990

CO2 laser application to the mineralized dental tissues--the possibility of iatrogenic sequelae.

From the many types of laser that are available commercially, the CO2 laser is presently thought to have the greatest potential for use in dentistry. An outline of the generation of emitted radiation from such a laser is given together with a review of work previously carried out and reported in the literature regarding application to the teeth. The main points of interest are the effects of radiation on the enamel and dentine, but concern is felt towards the possible iatrogenic damage of thermal origin that may occur within the pulp following irradiation of the dental tissues.

Carbon Dioxide↗
PubMed1990

Dentinal temperature transients caused by exposure to CO2 laser irradiation and possible pulpal damage.

An investigation is described that attempts to establish, in vitro, the characteristics of heat transference following laser irradiation of bovine dentinal tissue and the relationship with the periodicity of radiation. The results of this study appear to indicate that at depths of overlying dentine of up to 3 mm, laser-induced thermal injury to the pulp is a definite possibility. Fail-safe facilities to prevent build up of heat must be incorporated into the design of dental lasers to allow their beneficial effects to be utilized without the risk of iatrogenic damage.

Animals↗
PubMed1990

Initial comparison between endoscopic and conventional methods of caries diagnosis.

This study was designed to assess the feasibility and practicability of the employment of endoscopic methods for the diagnosis of dental caries and to compare the diagnostic performance, in posterior teeth, of visual endoscopic caries diagnosis (with and without the benefit of differential fluorescence) with that of conventional visual diagnosis, bite-wing radiography, and conventional transillumination. The two endoscopic methods were found to be clinically practicable, to be able to demonstrate the presence of small carious lesions, and to have both advantages and disadvantages compared to conventional methods. When all tooth sites were compared, the results indicated that the endoscopic methods may detect a greater number of carious lesions than do conventional visual, radiographic, or fiber-optic transilluminational methods of caries diagnosis. Further investigations involving histologic validation of diagnoses as well as larger numbers of patients and multiple examiners are indicated.

Adolescent↗
PubMed1989

An in vivo evaluation in children of the HPL bitewing device.

The HPL bitewing device, a new beam-aiming collimating bitewing film holder, has recently been developed. The aims of this study were to assess the practicability of using the new device clinically and to compare the diagnostic yield obtained with the new technique with those obtained using a conventional freehand method and the Rinn XCP instrument. For each of the three techniques a pair of bitewings was taken of 30 randomly selected patients aged 6-15 years. These bitewings were evaluated for technical errors using seven different criteria, including the number and severity of overlapping contacts. The results show that the HPL method produced the greatest number of unoverlapped surfaces and the smallest proportion of moderate and severe overlaps. For five of the seven criteria, the HPL method produced fewer technical errors than the other two methods. Assessment of the acceptability of the procedures to the children revealed few differences between the three radiographic techniques. Further studies of the new technique, involving larger numbers of patients and sequential radiographs, are indicated.

Adolescent↗
PubMedDate not supplied

Performance and reproducibility of a laser fluorescence system for detection of occlusal caries in vitro.

The diagnosis of occlusal caries at non-cavitated sites remains problematic, especially since clinical visual detection has limited sensitivity. Electrical methods of detection show considerable promise, but specificity is reduced. The aims of this in vitro study were: (1) to assess the validity of a new laser fluorescence device--the DIAGNOdent--(and compare the values with those of a fixed-frequency electrical device); (2) to determine the optimum cut-off points of the new device for different stages of the caries process, and (3) to assess the reproducibility of the new laser device. For validity and determination of optimum cut-off points, 105 extracted teeth with macroscopically intact occlusal surfaces were measured by a single examiner, using both the laser fluorescence device (on both moist and dried teeth) and an Electronic Caries Monitor. The teeth were subsequently examined histologically to determine the specificity, sensitivity and likelihood ratio at the D2 (caries extending through more than half of the enamel thickness) and D3 (caries involving dentin) levels. The values obtained for the laser device ranged from 0.72 to 0.87 (specificity), 0.76 to 0.87 (sensitivity) and 3.0 to 5.6 (likelihood ratio). Those for the ECM ranged from 0.64 to 0.78 (specificity), 0. 87 to 0.92 (sensitivity) and 2.4 to 4.1 (likelihood ratio). To determine intra- and interexaminer reproducibility of the DIAGNOdent, 11 dentists recorded two different measurements at the same site on a separate set of 83 extracted molar teeth, and these were compared using Cohen's kappa (at D2 and D3 levels) and Spearman's correlation coefficient. The average intra-examiner kappa scores were 0.88 (D2) and 0.90 (D3), with a Spearman correlation of 0.97. For interexaminer reproducibility, the average kappa values were 0.65 (D2) and 0.73 (D3), with a Spearman correlation of 0.84. It is concluded that for occlusal caries (1) the new laser device has a higher diagnostic validity than the ECM, and (2) in vitro, measurements using the device are highly reproducible. Thus, the laser device could be a valuable tool for the longitudinal monitoring of caries and for assessing the outcome of preventive interventions.

Dental Caries↗
PubMedDate not supplied

Relationships between a clinical-visual scoring system and two histological techniques: a laboratory study on occlusal and approximal carious lesions.

One aim of the present laboratory study was to determine whether a visual scoring system (ERK) developed for occlusal caries could be applied to approximal lesions. A new histological technique (autofluorescence, AF) recognises dentine that is soft and would be removed with an excavator during operative treatment. A second aim was to investigate the relationship between the visual scoring system (ERK) and AF of dentine both occlusally and approximally. The sample comprised 93 extracted teeth chosen to represent the range of visual scores on approximal and occlusal surfaces. After sectioning through the investigation site, the cut faces were examined in a stereomicroscope and the depth of demineralization was scored. Autofluorescence was viewed with a confocal laser scanning microscope. Results showed reasonable correlation between the visual scores and the stereomicroscope histological evaluations for occlusal surfaces and non-cavitated approximal surfaces. However, cavitated approximal surface lesions were less advanced histologically than cavitated occlusal carious lesions. The AF technique indicated that several lesions with intact surfaces would have had soft, excavatable dentine, whereas several with microcavities would not.

Dental Caries↗
PubMedDate not supplied

Tooth-brushing practices of parents and toddlers: a study of home-based videotaped sessions.

The aim of this pilot study was to investigate the tooth-brushing behaviour of parents and toddlers, by analysis of tooth-brushing sessions videotaped in families' homes. Eighteen families (self-selected from an ongoing preventive-intervention study) videotaped all home tooth-brushing sessions involving their toddler (average age 2.5 years) over a 24-hour period. The vast majority of families (89%) engaged in at least two sessions per day, usually supervised by mothers. The average length of the sessions was 142 s, although the brush tended to be in the child's mouth for less than half of that time. On average, only 10 s were spent brushing the front teeth, 13 s the back teeth, and 29 s spent on non-brushing activities (e.g., biting brush, sucking water). Three styles of brushing were identified, and families tended to be consistent in their use of these styles: exclusively parent-led (least common), exclusively child-led, and shared between parent and child (most common). In contrast with these poor behavioural outcomes, feedback from parents indicated that they were generally confident that the sessions had been effective in achieving clean teeth. These findings suggest that home-based tooth-brushing activity falls far short of professional expectations. Tooth-brushing, even with fluoride toothpaste, may be seriously compromised as a method of reducing caries in toddlers because teeth are being brushed too briefly.

Child, Preschool↗
PubMedDate not supplied

The prevalence of dental erosion in a United States and a United Kingdom sample of adolescents.

PURPOSE: A high prevalence of tooth surface loss due to erosion is well recognized in the United Kingdom (UK), but not in the United States (US). This could be due to prevalence or perception or a combination of both. The aim of this study was to measure the prevalence of erosion of the upper permanent incisors in US and UK samples of 11-13 year old children. METHODS: Convenience samples of 129 subjects were examined in the US and 125 in the UK by two trained examiners. The palatal and buccal surfaces of the upper permanent incisors were assessed for the presence of erosion. Subjects also completed a questionnaire investigating any association between the presence of erosion and possible etiological factors. RESULTS: The prevalence of erosion was 41% in the US and 37% in the UK samples, this difference was not statistically significant. Similarly no statistically significant difference was found between the sexes. The erosion present was confined to enamel in the vast majority of subjects. The questionnaire did not detect any link between the presence of erosion and possible etiological factors. CONCLUSION: The results of this study suggest that dental erosion is common in both US and UK adolescent populations. There is a need for a larger study to investigate this issue further.

Adolescent↗