Biomedical subjects

H Devlin

Publications and source records attributed to H Devlin.

At least 55 records · Page 3Linked to original sources

PubMed1995

The effect of ovariectomy on the healing tooth socket of the rat.

Under general anaesthesia, 35-day-old female rats were ovariectomized and the right maxillary molar teeth removed. Dynamic measures of alveolar bone formation were determined at 10 days after surgery, using the fluorochrome labelling technique, and compared with control animals. Ovariectomy significantly increased buccal resorption and palatal bone formation. In a second experiment, ovariectomized rats had the right maxillary molar teeth extracted and were killed at either 5 or 14 days after surgery. The mean mineralizing surface of the alveolar bone (percentage of surfaces occupied by a double fluorescent label) was significantly lower in rats killed at either 5 or 10 days than at 14 days after ovariectomy and tooth extraction. The mean appositional rate was significantly greater at 5 days after ovariectomy and tooth extraction than at 10 or 14 days. Oestrogen deficiency can therefore affect alveolar bone turnover following tooth extraction.

Alveolar Process↗

PubMed1995

Localization of pro-collagen type II mRNA and collagen type II in the healing tooth socket of the rat.

Sprague-Dawley rats (50 days old) were anaesthetized and the maxillary right molars extracted. The rats were killed at 2, 3, 6, 8 and 10 days after extraction. The maxillae were dissected and prepared for either routine histology, in situ hybridization for pro-collagen type II mRNA, or immunohistochemical detection of collagen type II. Pro-collagen type II mRNA was expressed maximally in the healing tooth socket at 8 days after the extractions, but the protein was not expressed at any time. This suggests that the translation of pro-collagen type II mRNA does not occur in osteoblasts following tooth extraction. Ossification was present in the socket at 6 days after the extractions, which is consistent with the suggestion that an early feature of osteoblastic differentiation may be the expression of type II pro-collagen mRNA.

Alveolar Process↗

PubMed1995

Mechanical behaviour and structure of light-cured special tray materials.

OBJECTIVES: This study relates some structural characteristics of representative special tray visible light cured (VLC) resin composites to their creep-recovery, hardness and flexural strength properties. VLC prosthodontic materials have not yet achieved the same acceptance as the VLC resin composites, perhaps because less is known of their structural and performance characteristics. METHODS: The VLC resin composites used were Triad, Convertray and Palatray. The inorganic composition was analysed quantitatively by heating known amounts of resin composite to 800 degrees C, and weighing the ash. Elemental composition was determined using X-ray microanalysis. Mechanical properties, including hardness, flexural behaviour and creep recovery, were obtained by standard methods. RESULTS: The inorganic filler content for Palatray was higher than that of Convertray or Triad, and the flexural modulus and flexural strength of Palatray were superior to that of Triad or Convertray. The mean maximum creep strain for the Palatray specimens was only 2.45% after 5 h loading under 37 MPa and there was a permanent set of 1.5% after 7 h recovery. CONCLUSIONS: Palatray exhibited superior overall properties and this evidently related primarily to the high volume fraction of filler.

Aluminum↗

PubMed1995

Oral manifestations of infantile systemic hyalinosis.

Oral manifestations of infantile systemic hyalinosis in a child of Asian origin are presented. Infantile systemic hyalinosis is a rare fatal condition with probably an autosomal recessive mode of inheritance. The symptoms become apparent soon after birth and death usually occurs before the age of two years. The systemic features are essentially due to widespread deposition of hyaline material in tissues. These include thickening and nodularity of skin, growth failure, joint contractures, osteoporosis, diarrhoea and recurrent infections. The oral changes in the case reported here included thickening of the oral mucosa, extensive overgrowth of gingival tissue, osteoporosis, marked curvature of the dental roots, and replacement of periodontal ligament by hyaline fibrous material. Immunohistochemistry revealed widespread presence of Type VI collagen in the connective tissue with particularly intense staining in the hyaline material.

Child, Preschool↗

PubMed1994

Replacement of missing molar teeth--a prosthodontic dilemma.

In deciding whether to replace lost lower molar teeth with a denture or accept the status quo, the dentist is faced with a choice of equally unfavourable alternatives. Dentures tend to accumulate plaque, the main cause of periodontal destruction, but failure to provide a prosthesis may also disadvantage the patient. Whether or not the provision of a replacement partial denture following molar tooth extraction helps to maintain the periodontium of the remaining dentition is not known. Patients are also aware of the dilemma. Many surveys have shown that a large proportion of replacement lower, free-end saddle dentures are never worn. However, a failure to provide partial dentures may have many adverse effects, especially in young adults.

Adaptation, Physiological↗

PubMed1994

Early alveolar ridge osteogenesis following tooth extraction in the rat.

Following tooth extraction, fluorochrome bone labels were injected intraperitoneally at intervals to identify mineralizing bone surfaces. At 5, 10 and 14 days post-extraction, the rats were killed. The mineral apposition rate, mineralizing surface and mineral formation rate were determined at various locations around the healing tooth socket. Linear trends in mineral apposition rate (p < 0.000001), mineralizing surface (p < 0.000001) and mineral formation rate (p = 0.00008) were seen around the socket, decreasing from gingivopalatal to gingivobuccal regions. These differences may be due to variations in vascularity as the gingivopalatal region is adjacent to the greater palatine artery. The mineral formation rate and mineralizing surface were significantly higher in the rats killed at 14 days after tooth extraction than at the other two post-extraction time points. This may be related to an earlier peak rate of bone resorption.

Alveolar Process↗

PubMed1994

Alveolar bone resorption: a histologic study comparing bone turnover in the edentulous mandible and iliac crest.

The extent of bone formation and resorption in alveolar and basal mandibular bone was measured in 17 edentulous individuals. For comparison, samples of iliac crest bone were also collected because this bone is often used for standard site assessment of skeletal measures of bone turnover. The specimens were processed for undecalcified resin histology. The results indicated extensive bone resorption at the periosteal surface of the alveolar crest, with little evidence of subsequent osteoid formation. Endosteal osteoid formation did occur, which tended to maintain the thickness of the cortical bone at the alveolar crest. Mandibular basal bone displayed a remodeling pattern similar to that seen in the iliac crest.

Aged↗

PubMed1994

Attitudes of dental students towards elderly people.

Questionnaires were distributed to first, third and fifth year dental students at two British dental schools, to assess their attitudes towards the elderly. A second follow-up questionnaire was given 1 year later to the five student years attending one of these dental schools, to compare attitudes and estimate how they affected their perceptions of treating this section of the community. In both questionnaire surveys, clinical dental students had a more positive attitude towards the elderly than did students in the non-clinical years of the course. In those students who had received both questionnaires on consecutive years, there was an improved attitude score. There were no significant differences in the attitudes of male and female students.

Adult↗

PubMed1993

The radiological features of calcifying odontogenic cyst.

Calcifying odontogenic cyst is a rare benign lesion of the jaws, with no particular specificity for age, sex or site. Three new cases are presented together with a review of the radiological literature. There appear to be no pathognomonic radiological features, although a superficial location on the affected bone and the presence of internal calcification may be useful signs. The role of radiology appears to be limited to determining lesion extent prior to surgery.

Adult↗

PubMed1992

Prosthetic rehabilitation of the edentulous patient requiring a partial maxillectomy.

A variety of problems faces the prosthodontist attempting reconstruction of maxillary defects. This article reviews developments in materials and techniques of obturator prosthesis design for patients experiencing maxillectomy. The size of the maxillectomy defect is one of the main factors governing the prognosis for treatment. Many patients require special prosthodontic techniques. However, routine attention to extension of the prosthesis and balanced occlusion is essential. Obtaining satisfactory retention and stability in the definitive obturator prosthesis can be elusive. Resilient denture base materials are extremely useful in retaining the prosthesis, which obturates small defects. However, the flexibility of these materials makes them unsuitable in large maxillectomy cavities because of the deformation that occurs during mastication. Alternative forms of retention, eg., osseointegrated implants and sectional prostheses retained by magnets, are discussed.

Animals↗

PubMed1992

Clinical bone densitometric study of mandibular atrophy using dental panoramic tomography.

Using the dental panoramic tomogram (DPT) and a nickel stepwedge, the prevalence of mandibular osteoporosis in 99 elderly, edentulous individuals was investigated densitometrically. A site was chosen on each DPT adjacent to the mandibular mental foramen and the optical density measured using a digital densitometer. Each DPT was then independently examined by a radiologist and the patients grouped into those exhibiting osteoporosis and those not. Twenty-seven of the patients exhibited qualitative evidence of osteoporosis on the DPT, using established radiological criteria. A large majority of this group was female (25 individuals, 93 per cent). Of the remaining 72 non-osteoporotic patients, only 32 (44 per cent) were female. There was a significant difference in the quantitative, densitometrically derived measurements of mandibular bone density between the osteoporotic and non-osteoporotic groups. The osteoporotic group had a mean optical density at the mandibular measurement site (mean D = -0.773, s.d. = 0.2) which was significantly different from that of the non-osteoporotic group (mean D = -0.888, s.d. = 0.21), t = 2.432, P less than 0.02. This previously diagnosed difference supports the validity of the densitometric technique. When all 99 patients were studied, the difference between the mean mandibular, equivalent nickel thickness of the males and females was significant (t = 2.32, P = 0.022). This sex difference could not be entirely accounted for by differences in the period of edentulousness or age of males and females.

Adult↗

PubMed1992

Bonding characteristics of a phosphonated anaerobic adhesive to amalgam.

The shear bond strength of a phosphonated anaerobic resin dental adhesive (Panavia-Ex) to amalgam was determined and clinically important parameters affecting the bond strength: amalgam type, surface finish and corrosion, were investigated. It is possible to bond to high copper set amalgam using this adhesive with a clinically useful shear bond strength. Three copper-enriched, single composition alloys were studied. One was a spherical alloy and two were lathe cut. The bond strength to one of the lathe-cut alloys was significantly lower than to the other two alloys. A significantly higher bond strength to aged lathe-cut amalgam than to fresh amalgam was found. However, Weibull analysis indicated that these latter changes were less consistent and indicated patchy, localized changes in the amalgam surface. The bond strength to the spherical alloy was significantly reduced by polishing with a finishing bur or Prophy-Jet. Therefore when bonding to a large amalgam restoration with such a phosphonated anaerobic adhesive, no polishing of the amalgam should be undertaken.

Adhesiveness↗

PubMed1992

Provision of domiciliary dental care for the older person by general dental practitioners in Scotland.

The databank at the Scottish Dental Practice Board (SDPB) was explored to determine the domiciliary care provided, for those patients over 70 years of age, by general dental practitioners under the National Health Service in one year. Three thousand nine hundred and forty-three (3943) courses of treatment were provided, via domiciliary visits to patients in this age category, by 38 per cent (1012) of dentists registered to provide dental care under the National Health Service. Whereas 34 per cent of dentists under 40 years of age provided domiciliary care, 46 per cent of those over 40 years provided such a service (P less than 0.001). In Scotland, approximately 1 per cent of 70-79-year-old patients and 2 per cent of patients over 80 years received domiciliary dental care over a 1-year period. For those elderly people who received such care, the mean percentage doubled for every 5-year increase in patient age.

Aged↗

PubMed1992

Serum parathyroid hormone and calcitonin levels following ovariectomy in the adult rat.

The ovariectomized rat is a reasonably good and often utilized model of human post-menopausal osteoporosis (Devlin and Ferguson, 1989). Mature rats were either ovariectomized or underwent a sham operation, killed at intervals following operation and the serum concentration of parathyroid hormone and calcitonin at death related to the histomorphometry of the cancellous bone of the proximal ilium. The mean serum calcitonin concentration for all ovariectomized rats was 66.4 pg/ml (SD = 18) and for the control rats was 76.42 pg/ml (SD = 20). The serum calcitonin concentration in the ovariectomized rats was significantly negatively correlated with the extent of erosion cavities of the cancellous bone (r = -0.598, t = -2.36, p = 0.039). No significant correlation was observed for the control rats (r = -0.107, t = -0.357, p = 0.727). The mean extent of erosion cavities in the ovariectomized group was 6.81% (SD = 1.94) and in the control group was 6.47% (SD = 2.21), with no significant differences between the two groups (t = 0.41, p = 0.69). No significant correlations were observed in serum parathyroid hormone (PTH) concentration with the bone resorption parameters. From this study it was concluded that calcitonin may be of aetiological importance in bone loss in the ovariectomized rat.

Animals↗

PubMed1991

Alveolar ridge resorption and mandibular atrophy. A review of the role of local and systemic factors.

Loss of alveolar bone from the edentulous jaws is a serious and common clinical problem, especially among the elderly. The retention and stability of dentures are reduced, but little is known about the pathogenesis of this bone loss. The existing data suggest that either local factors, for instance occlusal trauma, or systemic factors such as postmenopausal osteoporosis, contribute to edentulous alveolar bone resorption. This paper reviews the evidence for the aetiology of residual ridge resorption following tooth extraction.

Alveolar Bone Loss↗

PubMed1991

Measurement of mandibular bone mineral content using the dental panoramic tomogram.

The aim of this study was to determine whether bone mineral content could be estimated densitometrically using dental panoramic tomograms. A nickel stepwedge was attached to the film cassette to give a reference image on the radiographs. Four mandibles were radiographed and the optical density of a number of sites on the bone images measured. The calcium and phosphate content of the mandibles at these sites was measured by chemical analysis, using 3 mm diameter full thickness cores. The radiographically derived equivalent nickel thickness of the mandibular test sites was significantly correlated with calcium content (r = 0.62. P = 0.013), phosphate content (r = 0.633, P = 0.011), and dry bone weight (r = 0.541, P = 0.036), provided correction for soft tissue thickness was made. A clinical study is justified to determine whether the technique has sufficient accuracy to provide sequential data on individual patients and whether it may useful as a simple method of screening patients for mandibular osteoporosis.

Absorptiometry, Photon↗

PubMed1990

Cancellous bone resorption in the proximal ilium of the ovariectomized rat.

Bone histomorphometry was performed on the proximal ilium of mature Sprague-Dawley rats following ovariectomy, and these rats were compared with sham-operated controls. Bone volume per unit tissue volume (BV/TV), osteoid surface, and the depth and extent of eroded cavities were measured in animals killed at intervals after operation. The rate of bone loss and the mean osteoid surface in the proximal ilium of the ovariectomized rats was significantly greater than that of the control rats over a 210-day postoperative period. The eroded surface and mean trabecular thickness in the proximal ilium of the ovariectomized rats were not significantly different from that of the control rats, and therefore failed to explain the difference in the rate of bone loss. The distribution of the depths of trabecular eroded cavities in the ilium of ovariectomized rats was different from that in the control rats. The loss of trabecular bone mass in the proximal ilium of ovariectomized, mature rats appeared due to increased activity of individual osteoclasts, rather than to increased osteoclast numbers and thinning of trabeculae.

Animals↗

PubMed1990

The rate of incisor dentine calcification and of mandibular growth in the molar region of the ovariectomized rat.

In 14 ovariectomized and 15 control rats, killed at intervals over a 117-day period, the height of the mandible in the molar region was determined radiographically. Mandibular height was significantly related to time after operation in both groups, but their rate of mandibular growth was not significantly different. In a separate study, the rate of dentine formation in the right mandibular incisor of 9 ovariectomized and 10 control rats was calculated from the distance between two fluorescent labels injected at known time intervals. The rate of dentine apposition was measured at 117 and 201 days after ovariectomy. In both groups, the distance between the fluorescent labels was significantly correlated with the time interval between the injections. There was no significant difference between the rate of dentine calcification in either group. Transient changes in dentine apposition may have occurred post-ovariectomy which would be undetected at either 117 or 201 days after operation. There was thus no evidence for an effect of ovariectomy on either the rate of mandibular growth or dentine apposition.

Animals↗