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Biomedical subjects

R S Hobson

Publications and source records attributed to R S Hobson.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effect of food simulants on enamel-composite bond strength.

The effect of food simulants upon the enamel-composite bond strength of two orthodontic adhesive composites was studied. Thirty extracted premolars were used in each experimental group. Orthodontic brackets were bonded with either Transbond (3M Unitek) or Right-On (TP orthodontics) and were then exposed to either distilled water (control), 8 per cent ethanol (aqueous food), 50 per cent ethanol (alcoholic food), buffered lactic acid pH4 (acidic food), or corn oil (fatty food) for 12 weeks. Bond strength and Adhesive Remnant Index was recorded. It was found that 50 per cent ethanol had a significant effect upon the bond strength of both Transbond and Right-On. Right-On was affected to a greater extent. The clinical significance of this finding is that alcoholic mouth rinses, and alcohol-containing foods and drinks may be a causative factor in bond failure. However, the use of an alcoholic mouthrinse late in treatment may aid bracket removal. This potential use requires more research. Refereed Scientific Paper

Alcoholic Beverages↗
PubMed2000

A comparative micro-topographic study of the buccal enamel of different tooth types.

The aim of this study was to perform an in vitro examination of the etch pattern achieved on the orthodontic bonding area (OBA) of different tooth types, and to compare the extent and definition of etch achieved. Six examples of each permanent human tooth type were studied. These were collected from adolescents. A standardized etch regime was employed on the OBA and the etch pattern examined under the scanning electron microscope. The degree of definition of etch achieved on every third enamel prism was evaluated. Results showed that the extent of etch achieved decreased toward the distal end of each arch and was significantly less on the first molars (covering <2% OBA) than on the incisors (covering >90% OBA). It was also noted that the degree of definition became poorer towards the distal end of the arches and was worst on the mandibular molars. It is suggested that the etched enamel morphology of different tooth types could affect composite resin bond strengths. Consequently, this feature could effect the clinical survival of orthodontic brackets and contribute to the higher failure rate of brackets on posterior teeth.

Acid Etching, Dental↗
PubMed2000

An analysis of the skeletal relationships in a group of young people with hypodontia.

The objective of this investigation was to examine the dentofacial features of a group of patients with hypodontia, in particular assessing whether cephalometric analysis confirmed the clinical assumption of a reduced lower face height, and to determine the relationship of these facial features with different numbers of missing teeth. It took the form of a cephalometric study, undertaken in a dedicated Dental Hospital clinic for patients with hypodontia. The study group comprised 59 patients seen on the Hypodontia Clinic: 32 females, 27 males, mean age 13.1+/-3.1 years (range 6-23 years). The average number of missing teeth was 7 (SD 5), ranging from 1 to 21. The mean SNA, SNB, and MMA angles were within normal limits, but there was a statistically significant reduction in the MMA when more than one tooth type was missing (P = 0.007) and the ANB angle decreased as the number of missing tooth types increased (P = 0.034). The mean values for the whole sample were within the normal range and did not demonstrate any feature specific to the group, but patients with more severe hypodontia showed tendencies to a Class III skeletal relationship and a reduced maxillary-mandibular planes angle.

Adolescent↗
PubMed1999

Autotransplantation as a treatment option after loss of a maxillary permanent incisor tooth. A case report.

A case is described of the management of a maxillary left permanent incisor, damaged by several traumatic injuries, in a 13-year-old girl. The traumatized incisor tooth required extraction and as part of an orthodontic treatment plan, a mandibular left second premolar was surgically transplanted to the prepared extraction socket at the maxillary anterior alveolus. After splinting, the transplanted tooth underwent endodontic treatment, because of pulpal necrosis. Orthodontic treatment commenced 3 months post-transplantation. Permanent root obturation was provided after orthodontic treatment and a porcelain veneer was placed to restore aesthetic appearance. The case emphasizes the importance of correct case selection, a multidisciplinary approach to treatment planning, and regular follow-up for transplanted teeth.

Adolescent↗
PubMed1998

A pilot study of mineralization distribution in the cortical bone of the human mandible.

Twenty-three specimens from immediately anteroinferior to the mental foramen were obtained from male and female, dentate and edentate, human mandibles. Planoparallel 80 microm thick sections were prepared from the mandibular specimens and computerized quantitative microradiography undertaken, which allowed the production of mineralization frequency distribution curves and mean mineralization. No differences in mean mineralization with age, sex, presence or absence of dentition were found, but mineralization distribution curves indicated differences between males and females. Within the age range and small sample size examined (40-90 years) there were no age-related differences. There was a lower level of mineralization distribution in the edentulous than the dentate mandible.

Adult↗
PubMed1998

Posttreatment assessment of surgically exposed and orthodontically aligned impacted maxillary canines.

The records of 96 consecutively treated patients, with a total of 110 exposed maxillary canines, were reviewed after orthodontic alignment of the exposed teeth. In view of the high degree of clinical and patient satisfaction with the results, a random sample of 25 patients, with a total of 30 exposed canines, were critically assessed. The assessment involved scoring for clinical impression, mobility, gingival condition and pocketing, oral hygiene, vitality, and radiographic appearances. The results indicate that the technique of surgical exposure and orthodontic alignment of ectopic maxillary canines provides a satisfactory method of treatment.

Adolescent↗
PubMed1998

How UK orthodontists advise patients on oral hygiene.

In 1993, 1038 UK orthodontists (all the members of the British Association of Orthodontists and the British Society for the Study of Orthodontics) were asked by questionnaire about the oral hygiene advice they gave to patients undergoing routine orthodontic treatment. All the orthodontists gave advice on tooth brushing. Most (89.5 per cent) gave dietary advice and (84 per cent) used disclosing tablets. A fluoride rinse was recommended by 73 per cent and a chlorhexidine mouthwash by 41.9 per cent. Many orthodontists advocate appropriate oral hygiene measures, but the efficacy of such methods is determined by the patient's motivation. The orthodontist therefore requires skills in behavioural management. Oral hygiene measures may be more cost-effective when undertaken by trained auxiliaries.

Counseling↗
PubMed1997

Preliminary quantitative microradiography study into the distribution of bone mineralization within the basal bone of the human edentulous mandible.

Six edentulous human hemimandibles (three male, three female) of similar ages were sectioned transversely at the midline, mental foramen, midway between mental foramen and angle (body), and angle of the mandible. Planoparallel sections were prepared of the cortical plate on buccal and lingual surfaces and microradiographed alongside an aluminium step-wedge for computerized quantitative microradiography. Mean mineralization values and mineralization frequency distribution curves were calculated. Gender had no effect on the mean mineralization values, but did show a significant difference in the mineralization frequency distribution. There was no difference in mean mineralization between lingual and buccal cortical plates, but the distribution curves differed, with the lingual cortex distributions being more uniform. Each sample site was significantly different from all others, with the mental foramen and body sites showing the greatest variation in distribution of mineralization level.

Aged↗
PubMed1996

Perception of stimulus size in patients with burning mouth syndrome.

Twenty subjects with burning mouth syndrome (BMS) and 20 control subjects were tested for oral size perception. Blindfolded subjects assessed the size of holes (2.38-12.70 mm diameter) presented to the tongue, using their fingers to select a matching hole from a comparator series of 31 holes (0.76-15.87 mm diameter) using first static then phasic touch. Both groups overestimated the size of the holes less than 10 mm in diameter but no systematic disparity was evident with holes greater than 10 mm in diameter. The relationship between the stimulus size and the illusion (expressed as the ratio of apparent size to real size) was hyperbolic, with the illusion tending towards unity for holes greater than 10 mm. No differences were found in object size perception amongst patients with BMS or control subjects. It is therefore unlikely that altered oral size perception is a precipitating factor or accompanying feature in patients with BMS.

Adult↗
PubMed1996

Airway efficiency during the use of SCUBA diving mouthpieces.

OBJECTIVE: To investigate the effect of varying interdental bite platform thickness of the scuba mouthpiece on airway efficiency. METHODS: 10 male divers had their mean peak flow measured for free breathing, maximum flow with diving mouthpiece, teeth in occlusion, and for five experimental mouthpieces with different thickness of interdental bite platform (1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). RESULTS: The connecting airway between the demand valve and mouthpiece was found to be a major limiting factor in airway efficiency. An interdental bite platform of 4 mm resulted in the greatest air flow with a further increase in thickness resulting in air flow restriction. CONCLUSIONS: The use of an interdental bite platform of 4 mm placed between the premolar and molar teeth ensures the greatest airway efficiency and also results in a design which provides the least temporomandibular joint discomfort for the diver.

Adult↗
PubMed1995

Management of the orthodontic patient 'at risk' from infective endocarditis.

There are no clear guidelines for the application of current antibiotic prophylactic regimes to orthodontic patients at risk from infective endocarditis. In order to ascertain current practice, a survey on various aspects of the management of orthodontic patients at risk from infective endocarditis was undertaken. Questionnaires were sent to all 1038 members of the British Society for the Study of Orthodontics and the British Association of Orthodontists. A total of 518 replies were received, 480 (46%) of which were completed in full and analysed. Eight cases of infective endocarditis associated with orthodontic treatment over a 44-year period were reported. The majority of respondents underestimated the number of at risk patients likely to be encountered over a 5-year period. Most orthodontists routinely contact the medical practitioner (62%) or hospital consultant (65%) for advice on the prescription of prophylactic antibiotics. Only 58 (12%) claimed to have refused orthodontic treatment for at risk patients. The majority of respondents advise the use of antibiotic prophylaxis for band placement and removal and manipulation of an unerupted tooth. A high standard of oral hygiene must be established prior to orthodontic treatment for at risk patients. Antibiotic prophylaxis in orthodontics should be used for procedures which cause gingival trauma eg band placement and removal. The daily use of a chlorhexidine mouthwash during treatment and prior to appliance adjustment is recommended.

Adolescent↗
PubMed1995

The design and construction of customised mouthpieces for subaqua diving.

Previous studies have shown that many subaqua divers suffer from temporomandibular joint dysfunction and related problems associated with the use of commercially available diving mouthpieces. This paper highlights factors which play a role in the development of these problems, defines essential features required in mouthpiece design and describes a technique for the construction of a fully customized mouthpiece.

Athletic Injuries↗
PubMed1993

Infective endocarditis associated with orthodontic treatment: a case report.

A case of acute bacterial endocarditis associated with orthodontic treatment is described and the problems associated with orthodontic treatment for 'at risk' patients are discussed. The American Heart Association recommendations for orthodontic patients are summarized, and the general recommendations of the Endocarditis Working Party of the British Society for Antimicrobial Chemotherapy are appended.

Adult↗
PubMed1991

Temporomandibular dysfunction syndrome associated with scuba diving mouthpieces.

As previous reports have highlighted that temporomandibular joint dysfunction syndrome can occur during scuba diving due to the use of a diving mouthpiece, 74 divers of varied experience (62 male, 12 female) were asked to evaluate the efficiency of the mouthpiece for the ease of grip, insertion into the mouth, clearing of water, air sharing, comfort and overall efficiency. They also recorded the level of muscle and joint discomfort experienced during diving and non-diving activities. The results indicate that temporomandibular joint problems unrelated to diving are compounded by the use of a diving mouthpiece. The diver's assessment of muscle tension and comfort while using the mouthpiece was found to be a good predictor of whether temporomandibular dysfunction would occur and the assessment scores have been used in a formula to aid selection of a mouthpiece.

Diving↗
PubMed1988

The effect of smoking on immediate post-extraction socket filling with blood and on the incidence of painful socket.

The effect of habitual smoking on post-extraction socket filling with blood and on the incidence of painful socket, was investigated. Data were collected from 2417 adult dental out-patients in whom 3541 extractions were performed under local anaesthesia. Post-operative socket filling with blood was significantly reduced in smokers, compared with non-smokers (p less than 0.01). There was a higher incidence of painful socket in heavy smokers (20 or more cigarettes per day), compared with nonsmokers (p less than 0.05). There was a significant relationship between immediate post-extraction socket blood level and the incidence of painful socket; sockets which showed poorer filling were more likely to develop painful socket (p less than 0.02). Smoking appeared to have an adverse effect upon the healing of extraction wounds.

Adolescent↗