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Biomedical subjects

G J Roberts

Publications and source records attributed to G J Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1990

Inhalation sedation (relative analgesia) with oxygen/nitrous oxide gas mixtures: 1. Principles.

Inhalation sedation with low-to-moderate concentrations of nitrous oxide in oxygen has a remarkable safety record--in over 45 years of use there has not been any mortality or serious morbidity recorded. It is not surprising therefore that the use of the technique is increasing steadily, as it has been shown to be an effective method of managing patients' anxiety. In this two-part article the author explains the procedure. In Part 1 he reviews the principles of relative analgesia: describing the characteristics of the different planes of sedation, the mechanism of uptake and elimination of nitrous oxide, and the need for scavenging. In Part 2 he will give a detailed practical guide to the modern technique, incorporating the subtle changes that have been developed over the last ten years.

Air Pollutants, Occupational↗
PubMed1990

Dental maturity in children with chronic renal failure assessed from dental panoramic tomographs.

Children with chronic renal failure are known to lag behind normal children for both height achievement and bone age. In the present study, dental maturity was assessed by scoring dental panoramic tomographs using two methods. The method of Dermirjian gave closer estimates of the chronological age than that of Leinonen. With the former method, dental maturity was found to be slightly delayed in children with chronic renal failure, although this was not statistically significant.

Adolescent↗
PubMed1989

Talon cusp: report of a case.

The methods of treatment of talon cusps are reviewed. A case is reported in which a calcium hydroxide pulpotomy was carried out on an upper central incisor with a talon cusp. This was necessary to enable (a) complete reduction of the cusp within a feasible time span, and (b) maintenance of pulpal vitality in order to allow apical development of the immature root.

Calcium Hydroxide↗
PubMed1989

A morphometric and quantitative microradiographic study of dental tissues in the hypopituitary dwarf mouse.

In transverse sections the areas of enamel, dentine and pulp were determined using image analysis morphometry, and the mineralization levels of enamel, dentine and alveolar bone using quantitative microradiography and a microphotometric-microdensitometric technique. There were significant differences in the ratios of dentine to pulp area, and in the enamel to total area in the incisors from dwarf and normal animals. The mean dentine to pulp ratio for dwarf incisors was more than six times greater than in normal incisors. There was also a significantly greater variation in the dentine to pulp ratio in dwarfs, which was attributed to their greater variation in pulp size. Values for mineral density of enamel, dentine and bone were similar to those found by other investigators. For example, for normal specimens, the mean mineral density of outer enamel was 2.84 g/cm3 (SD = 0.38), percentage mineralization 92%; outer labial dentine was 1.64 g/cm3 (SD = 0.15), percentage mineralization 52%; and alveolar bone was 1.53 g/cm3 (SD = 0.13), percentage mineralization 49%. The variation in mineralization within each tissue confirmed previous work in rodents. There was a consistent trend for mineralization levels of all hard tissues in the dwarf sample to be less than in the normal sample but the difference was not statistically significant for any one tissue.

Alveolar Process↗
PubMed1989

Hypocalcification and hypoplasia in primary teeth of pre-school children from different ethnic groups in South Africa.

A study was completed in 1985/86 which examined the dental health of pre-school children from different ethnic groups and communities in South Africa: rural black, urban black, urban colored, urban Indian, and urban white. Enamel defects were recorded in primary teeth by use of the HHI, an index developed to measure hypocalcification and hypoplasia of enamel. The findings showed that colored children had the greatest number of enamel defects. The teeth most commonly affected were the maxillary anterior teeth and mandibular molar teeth. It is suggested that further epidemiological studies utilizing the HHI should be undertaken in pre-school children, especially from developing countries, to gain more information on the causes of enamel defects in the primary dentition and the possible use of such findings to predict nutritional health of individuals.

Child, Preschool↗
PubMed1989

Complications of open tibial fractures.

Ninety-six open tibial shaft fractures in 93 patients were examined to determine the incidence of amputation, nonunion and infection in each of three types of open fractures. Amputation occurred in four patients, who had type III fractures. Nonunion developed in two of 20 type II fractures, and 16 of 59 patients with type III fractures did not result in amputation (three of 62 total type III open fractures resulted in immediate amputation). Infection occurred in one of the 20 type II open fractures and 14 of 59 type III fractures. The distribution of infection and nonunion in the three grades of open fractures proved to be statistically significant, whereas the occurrence of amputation did not.

Adolescent↗
PubMed1988

The midline cartilages of the cranial base of the hypopituitary dwarf mouse (dw/dw). A histological and autoradiographic study.

The dwarf mice used in this study demonstrated severe growth retardation related to the 5 endochondral growth sites of the midline cranial base. The principal defect appears to be a dramatic reduction of activity as judged by comparing the histology of the dwarf mice with their normal litter mates. The principal defect appears, from the [3H]thymidine data, to be a complete cessation of mitotic activity in the proliferative zone. It is not possible, from the present study, to say whether activity in the matrixogenic zone is also reduced. The anomalous enlargement of hypertrophic cells by 80 days in dwarf mice is unexplained.

Animals↗
PubMed1985

A radiographic study of dental development in the hypopituitary dwarf mouse.

Growth in body length, skeletal lengths, incisor lengths and molar root lengths were retarded in dwarf mice. The root lengths of third molars were more severely affected than those of other molars. The crown lengths at the enamel-cementum junction of upper and lower molars of most dwarf mice were significantly shorter than normal. The root canals of dwarf mice were smaller, apical closure was delayed and there was a delay in their eruption to the occlusal level. Although the size of the dentition was markedly affected in the dwarf mice, the functional relationship appeared to be unchanged.

Animals↗
PubMed1984

Can breast feeding cause dental caries?

Recently there have been several reports from the USA and UK which suggest that under certain rare conditions breast feeding may cause rampant (severe) dental caries. This paper provides a critical review of the available information and gives some experimental evidence suggesting that human milk possesses a greater cariogenic potential than bovine milk. It is concluded that, although it is possible for human and bovine milk to cause dental caries, the prevalence would appear to be very low and is associated with breast or bottle feeding which has continued until at least two years of age on many occasions during the day and night.

Animals↗
PubMed1984

Growth of the cartilages of the mid-line cranial base: an autoradiographic study using tritium labelled thymidine.

Proliferative and kinetic activity of chondrocytes in five sites of endochondral growth in the mid-line cranial base of the rat have been studied using a single injection of 3H-thymidine in animals aged 4-80 days. The marked caudorostral gradient and temporal gradient of the labelling index and labelling profiles is indicative of a proliferative activity specific to each endochondral growth site. Measurements of the growth rate indicate that each growth site in the cranial base bones has a specific growth rate.

Aging↗