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Biomedical subjects

M P Hector

Publications and source records attributed to M P Hector.

At least 19 recordsLinked to original sources
PubMed2007

Impact of sleep nasendoscopy on the outcome of mandibular advancement splint therapy in subjects with sleep-related breathing disorders.

AIM: To evaluate the impact of positive sleep nasendoscopy, with simultaneous mandibular advancement, on the outcome of mandibular advancement splint therapy in 120 subjects with sleep-related breathing disorders. METHODOLOGY: Overnight polysomnography and sleep nasendoscopy were performed prior to splint therapy. Follow-up sleep studies, with the appliance in situ, were undertaken for those patients with obstructive sleep apnoea. Subjective outcome measures assessed daytime sleepiness and snoring. RESULTS: One hundred and seven (89 per cent) subjects completed the study. Follow-up sleep studies confirmed the efficacy of treatment, with patients showing a mean reduction in apnoea/hypopnoea index (from 18.9 to 4.9, p<0.001), Epworth sleepiness scale scores (from 11 to seven, p<0.001) and partner-recorded snoring scores (from 14 to eight, p<0.001). CONCLUSION: Sleep nasendoscopy, with concomitant mandibular advancement to mimic the treatment effect, could be of prognostic value in determining successful mandibular advancement splint therapy.

Adult↗
PubMed2006

Accuracy of age estimation of radiographic methods using developing teeth.

Developing teeth are used to assess maturity and estimate age in a number of disciplines, however the accuracy of different methods has not been systematically investigated. The aim of this study was to determine the accuracy of several methods. Tooth formation was assessed from radiographs of healthy children attending a dental teaching hospital. The sample was 946 children (491 boys, 455 girls, aged 3-16.99 years) with similar number of children from Bangladeshi and British Caucasian ethnic origin. Panoramic radiographs were examined and seven mandibular teeth staged according to Demirjian's dental maturity scale [A. Demirjian, Dental development, CD-ROM, Silver Platter Education, University of Montreal, Montreal, 1993-1994; A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227; A. Demirjian, H. Goldstein, New systems for dental maturity based on seven and four teeth, Ann. Hum. Biol. 3 (1976) 411-421], Nolla [C.M. Nolla, The development of the permanent teeth, J. Dent. Child. 27 (1960) 254-266] and Haavikko [K. Haavikko, The formation and the alveolar and clinical eruption of the permanent teeth. An orthopantomographic study. Proc. Finn. Dent. Soc. 66 (1970) 103-170]. Dental age was calculated for each method, including an adaptation of Demirjian's method with updated scoring [G. Willems, A. Van Olmen, B. Spiessens, C. Carels, Dental age estimation in Belgian children: Demirjian's technique revisited, J. Forensic Sci. 46 (2001) 893-895]. The mean difference (+/-S.D. in years) between dental and real age was calculated for each method and in the case of Haavikko, each tooth type; and tested using t-test. Mean difference was also calculated for the age group 3-13.99 years for Haavikko (mean and individual teeth). Results show that the most accurate method was by Willems [G. Willems, A. Van Olmen, B. Spiessens, C. Carels, Dental age estimation in Belgian children: Demirjian's technique revisited, J. Forensic Sci. 46 (2001) 893-895] (boys -0.05+/-0.81, girls -0.20+/-0.89, both -0.12 y+/-0.85), Demirjian [A. Demirjian, Dental development, CD-ROM, Silver Platter Education, University of Montreal, Montreal, 1993-1994] overestimated age (boys 0.25+/-0.84, girls 0.23+/-0.84, both 0.24 y+/-0.86), while Nolla [C.M. Nolla, The development of the permanent teeth, J. Dent. Child. 27 (1960) 254-266] and Haavikko's [K. Haavikko, The formation and the alveolar and clinical eruption of the permanent teeth. An orthopantomographic study, Proc. Finn. Dent. Soc. 66 (1970) 103-170] methods under-estimated age (boys -0.87+/-0.87, girls -1.18+/-0.96, both -1.02 y+/-0.93; boys -0.56+/-0.91, girls -0.79+/-1.11, both -0.67 y+/-1.01, respectively). For individual teeth using Haavikko's method, first premolar and second molar were most accurate; and more accurate than the mean value of all developing teeth. The 95% confidence interval of the mean was least for mean of all developing teeth using Haavikko (age 3-13.99 years), followed by identical values for Demirjian and Willems (sexes combined).

Adolescent↗
PubMed2005

Epidermolysis bullosa and dental developmental age.

OBJECTIVES: The dental development of permanent mandibular teeth in a small group of children with dystrophic epidermolysis bullosa (DEB) was assessed from radiographs and compared to a healthy, age-and-sex-matched control group. METHODS: This was a retrospective radiographic cross-sectional study. The sample consisted of a group of 44 children aged between 4 and 15 years with DEB and healthy, age-and-sex-matched controls. Two quantitative methods of assessing tooth formation were used: (1) a combination of information about tooth length and apex width; and (2) the use of tooth length to predict age. Panoramic radiographs were digitized in order to determine tooth length and apex width. Dental age was calculated, and the difference with real age was tested with Student's t-test. RESULTS: The dentition of both the DEB and control groups was slightly delayed. Using the first method, the delay was 0.34 +/- 0.87 years for the DEB group and 0.29 +/- 0.97 years for the control group. Using the second method, the delay was 0.49 +/- 1.18 years for the DEB group and 0.23 +/- 0.62 years for the control group. This delay was not statistically significant for either method. CONCLUSIONS: The dental formation of permanent mandibular teeth in the group of children with DEB was not significantly different to that found in the control group.

Adolescent↗
PubMed2004

Chewing side preferences in children.

The dentition of 57 children aged 6-8 years old was examined clinically and radiographically. Subjects were divided into groups according to state of the dentition: caries free, no pathology and no pain; caries, no pathology and no pain; caries, pathology and no pain; caries, pathology and pain. The existence of a preferred chewing side (PCS) was determined using a visual spot-checking method. Subjects were instructed to chew gum on their posterior teeth. After 15 s the position of the chewing gum was recorded as right or left. This procedure was carried out seven times consecutively. Subjects had an 'observed preferred chewing side' (OPCS) when they chewed 5/7, 6/7 or 7/7 times on the same side. To determine if children were aware of their chewing side preference each subject's stated PCS was then recorded as left, right or none. 'Coincidence' between stated and OPCSs was said to occur if the stated PCS corresponded to the OPCS. Seventy-seven per cent of children had a PCS. The majority (70%) of caries free children also had a PCS (P < 0.05). The percentage with an OPCS varied from 70% of the caries free group to 92% of the group with caries, pathology and pain. However, there was no statistically significant association between state of the dentition and the presence of a PCS. Coincidence occurred in 56% of children. There was a statistically significant association between state of the dentition and coincidence (P=0.02). Children in pain were most likely to show coincidence (kappa=0.81).

Awareness↗
PubMed2004

Protective effect of salivary nitrate and microbial nitrate reductase activity against caries.

To test the hypothesis that a combination of high salivary nitrate and high nitrate-reducing capacity are protective against dental caries, 209 children attending the Dental Institute, Barts and The London NHS Trust were examined. Salivary nitrate and nitrite levels, counts of Streptococcus mutans and Lactobacillus spp., and caries experience were recorded. Compared with control subjects, a significant reduction in caries experience was found in patients with high salivary nitrate and high nitrate-reducing ability. Production of nitrite from salivary nitrate by commensal nitrate-reducing bacteria may limit the growth of cariogenic bacteria as a result of the production of antimicrobial oxides of nitrogen, including nitric oxide.

Adolescent↗
PubMed2003

The accuracy of three methods of age estimation using radiographic measurements of developing teeth.

The accuracy of age estimation using three quantitative methods of developing permanent teeth was investigated. These were Mörnstad et al. [Scand. J. Dent. Res. 102 (1994) 137], Liversidge and Molleson [J. For. Sci. 44 (1999) 917] and Carels et al. [J. Biol. Bucc. 19 (1991) 297]. The sample consisted of 145 white Caucasian children (75 girls, 70 boys) aged between 8 and 13 years. Tooth length and apex width of mandibular canine, premolars and first and second molars were measured from orthopantomographs using a digitiser. These data were substituted into equations from the three methods and estimated age was calculated and compared to chronological age. Age was under-estimated in boys and girls using all the three methods; the mean difference between chronological and estimated ages for method I was -0.83 (standard deviation +/-0.96) years for boys and -0.67 (+/-0.76) years for girls; method II -0.79 (+/-0.93) and -0.63 (+/-0.92); method III -1.03 (+/-1.48) and -1.35 (+/-1.11) for boys and girls, respectively. Further analysis of age cohorts, found the most accurate method to be method I for the age group 8.00-8.99 years where age could be predicted to 0.14+/-0.44 years (boys) and 0.10+/-0.32 years (girls). Accuracy was greater for younger children compared to older children and this decreased with age.

Adolescent↗
PubMed2003

Periodontal mechano-sensory responses following trauma to permanent incisor teeth in children.

The aim of this study was to investigate mechano-sensory responses of injured and uninjured incisor teeth. Twenty-five children who had experienced dental trauma, together with age- and gender-matched controls, were studied prospectively. Touch thresholds of incisor teeth from both groups were determined using calibrated sets of von Frey hairs (force range 0.5-10.0 g in 0.5 g increments) using a forced choice staircase method. Forces were applied perpendicular to the buccal enamel surfaces along the midline, 2 mm from the incisal edge. Touch threshold was defined as the lowest force detected in three out of the five occasions. Following statistical analysis, P < 0.05 was considered significant. At initial examination, the touch threshold values of 25 traumatised teeth were significantly greater than the untraumatised controls (P < 0.001), and these values approached those of the control teeth over 3-12 months (P > 0.05). Dental trauma was associated with increased touch thresholds in permanent incisor teeth, with recovery toward healthy control values usually occurring between 3-12 months.

Adolescent↗
PubMed2001

Children and informed consent: a study of children's perceptions and involvement in consent to dental treatment.

AIM: The aim of the study was to find out to what extent children are involved in consenting to their dental care. METHODS: It was conducted using a structured interview with 60 8-13-year-old children. In the control group, verbal consent was given by the parent, whilst in the study group written consent was given by the parent and verbal assent by the patient. Interviews were conducted after dental treatment. RESULTS: The findings indicate that children in the study group felt they were more involved in deciding about their dental treatment compared with the control group. CONCLUSION: Children want to be more involved in consenting to their dental treatment.

Adolescent↗
PubMed2001

Levels of pre-kallikrein in resting and stimulated human parotid and submandibular saliva.

Salivary tissue kallikrein is stored in an active form in human salivary glands. Pre-kallikrein has been demonstrated in mixed saliva, but it is not clear if the various salivary glands contribute equally. This study set out to determine if pre-kallikrein is present in human parotid and submandibular salivas at rest, whether levels change during stimulation, and to compare the pattern of pre-kallikrein and kallikrein secretion with that of total protein. Resting and citric acid-stimulated parotid and submandibular, and gum-stimulated parotid saliva samples were collected from 6 healthy subjects. Salivary flows were determined gravimetrically. Total protein concentration and kallikrein enzymic activity were assayed using standard techniques. Pre-kallikrein was assayed following trypsinisation of duplicate samples. Pre-kallikrein was present in parotid and submandibular ductal saliva. Proportions of pre-kallikrein and active kallikrein were similar in salivas secreted at rest and during stimulation, and both outputs mirrored protein output in both major glands. Gum-stimulated parotid saliva showed lower activity than resting, and no differences were seen between resting and stimulated submandibular samples.

Adult↗
PubMed2001

The distribution of stimulated saliva in children.

OBJECTIVES: The need for an adequate quantity of saliva to maintain oral health has been widely reported. It is not only the quantity that is important, but also how the saliva is distributed once it enters the mouth. Several studies have looked at how saliva is distributed around adult mouths. The aim of this experiment was to describe the distribution of stimulated saliva around the mouth in children. SAMPLE AND METHODS: In order to demonstrate the distribution of saliva around the mouth under stimulated conditions, 25 child subjects were asked to chew a piece of chewing gum containing 1.5 mg erythrosin for 3 min on one side of the mouth. The distribution of dye in the mouth was recorded on standardized charts. RESULTS: In all cases, dye was present ipsilateral to the chewing side. In 13 cases (52%) the dye did not cross the midline and of the remaining 12 children the dye only reached the contralateral canines in four of them (16%). CONCLUSIONS: Evidence is presented which suggests that during unilateral chewing in children, saliva is not well distributed around the mouth and has a tendency to stay on the side of the mouth from where it was secreted (P < 0.01).

Bicuspid↗
PubMed2001

Critical pH in resting and stimulated whole saliva in groups of children and adults.

OBJECTIVE: The concentrations of calcium and phosphate in saliva have significant influence on the protective mechanisms of dental hard tissues within the oral environment. A lower calcium concentration means: 1) a lower thermodynamic driving force for hydroxyapatite precipitation at normal oral pH; 2) a higher driving force for hydroxyapatite dissolution at low pH; 3) a lower critical pH. The aims of this study were to: 1. determine the calcium and phosphate concentrations 2. calculate the critical pH for enamel and 3. determine the driving forces for demineralization and remineralization in a group of children and adults. METHODS: In this comparative study, calcium and phosphate concentrations were measured in the resting and stimulated saliva of child and adult volunteers using a spectrophotometric system used in routine blood analysis. Salivary flow rates were also measured in each group. RESULTS: The calcium concentrations were lower in children than adults, but the phosphate concentrations were not significantly different. The critical pH was significantly higher for children than adults in both resting and stimulated saliva. Therefore, the thermodynamic driving forces for; (1) demineralisation at low oral pH, is greater, and (2) for remineralisation at normal oral pH, is lower, in children compared to adults. CONCLUSION: The results of this study show that from thermodynamic considerations alone, there is increased risk of demineralization in children compared with adults.

Adult↗
PubMed2000

Precipitation of specific proteins by freeze-thawing of human saliva.

Frozen saliva samples demonstrate a variable amount of precipitate on thawing depending on the type of secretion [submandibular-sublingual (SML) greater than parotid]. This precipitate has been resuspended using EDTA or removed by centrifugation by some workers and others do not mention it. Yet others collect the salivas into EDTA or centrifuge them before freezing. To determine the adsorption of proteins to hydroxyapatite, prior treatment with EDTA would be disadvantageous. The aim here was to determine if the protein pattern in parotid and SML saliva as demonstrated by sodium dodecyl sulphate gel electrophoresis is affected by the formation of precipitates. Portions of parotid and SML saliva were thawed and treated in the following ways: (a) mixed vigorously with a vortex mixer; (b) centrifuged to remove the precipitate; (c) mixed with EDTA (1 and 5 mmol final concentration for parotid and SML samples, respectively) to resuspend the precipitate. The samples were loaded on to gradient (5-20%) SDS gels and, following electrophoresis, the gels were stained with Coomassie brilliant blue R-250. The protein patterns obtained for (a) and (c) were the same. The centrifuged samples demonstrated loss of a specific band of less than 14 kDa, although this was less obvious in the parotid samples. The SML samples also showed a reduction in other lower molecular-weight proteins. This study demonstrates that precipitates in thawed frozen salivas contain specific proteins and that these samples require careful handling to avoid any alteration in the overall protein composition.

Chemical Precipitation↗
PubMed2000

Significance of saliva for the denture-wearing population.

UNLABELLED: This paper summarises a series of studies already published in German and presents new data related to the aetiology of the 'dry mouth' and its associated problems. AIMS: To study factors affecting mucous and serous salivary gland secretion, the aetiology of the 'dry mouth' and its associated problems, causative factors for hyposalivation and it's treatment. SETTING: Two university dental hospitals. SUBJECTS: 587 denture wearers and 521 control subjects, and autopsy material. INTERVENTIONS: Exercise, chewing, water, oestrogen, pilocarpine, and anetholtrithion therapy, biopsy of the minor glands. MAIN OUTCOME MEASURES: Palatal secretion (PAL, microL/cm2/min) and parotid salivary flow (PAR), subjective complaints and clinical findings. RESULTS: Resting flow rates for PAL between 0 and 65 microliters/cm2/min were seen in every age group. The flow rates of PAR (0 to 3.7 ml/10 min) were not correlated with PAL. Most patients with a resting flow rate of PAL < or = 6.0 microliters/cm2 suffer from a 'dry mouth' and Burning Mouth Syndrome (BMS) or oral dysaesthesia (OD) with or without chronic lesions of the oral mucosa. Etiological factors for the incidence of reduced PAL and associated problems include xerostomic drugs, oestrogen deficiency, radiotherapy, thyroid dysfunction, smoking or continuous wearing of complete upper dentures. PAL also correlated with the retention of upper complete dentures. PAL was correlated with the water content of epithelial tissues. PAL and PAR were both increased by drinking ample fluid, improving their circulation by physical exercises, chewing intensively, or taking oestrogens, pilocarpine, anetholtrithion. CONCLUSIONS: Variation in palatal salivary secretion occurs and is clinically important.

Adult↗
PubMed1999

On the pulpal nerve supply in primary human teeth: evidence for the innervation of primary dentine.

The presence of nerves in human tooth pulp has been recognized for over a hundred years, and the innervation of dentine for about 40 years. These observations have been made in permanent teeth. Very few studies have reported on the innervation of the primary pulp and dentine. The purpose of this study was to describe the innervation of the primary tooth pulp-dentine complex. Ten mature primary teeth (one incisor, six canines and three molars) were used. Immediately following extraction they were divided into three sections using a diamond disc and saline coolant. They were then immersion fixed in a solution of formaldehyde and picric acid dissolved in a phosphate buffer pH 7.4). The teeth were then demineralized for 1-3 weeks in formic acid. Following complete demineralization, 30 microns sections were cut on a freezing microtome. Neural tissue was stained using a specific antibody to calcitonin gene related peptide (CGRP). Sections were mounted on glass slides and examined using light microscopy. No individual nerve fibres were seen in the control sections, suggesting that the method used was specific for CGRP-containing nerve fibres. The primary teeth appeared to be well innervated. Myelinated and unmyelinated nerves were seen. There was a dense but variable subodontoblastic plexus of nerves (plexus of Raschkow) and nerve fibres were seen to leave this to travel towards the odontoblast layer. Most terminated here, but a few penetrated the odontoblast layer to enter predentine and the dentine tubules. The maximum penetration was 125 microns but most terminated within 30 microns of the dentinopulpal junction. The coronal region was more densely innervated than the root. Within the crown the cervical third was the most densely innervated region, followed by the pulp horn and the middle third. In conclusion, this study has demonstrated that mature primary tooth contains a pulp which is well innervated and has many nerve endings terminating in or near the odontoblast layer, with a small number penetrating into dentine.

Calcitonin Gene-Related Peptide↗
PubMed1999

Dental maturation in British children: are Demirjian's standards applicable?

OBJECTIVE: The objective of this study was to determine if the standards of dental maturation of Demirjian et al. (1973, 1976) are applicable to British children. DESIGN: The design was cross-sectional, retrospective. SAMPLE AND METHOD: The sample comprised 521 London children of Bangladeshi and white Caucasian (English, Welsh and Scottish) origin aged between 4 and 9 years. Dental age was assessed by crown and root stages of seven mandibular teeth from rotational pantomographs. Dental age was compared to chronological age using a t-test. RESULTS: Differences in dental maturation between the two ethnic groups were not significant. British children as a group were dentally advanced compared to the Canadian standards. The mean (+/- standard deviation) advancement in girls was 0.51 +/- 0.79 years and in boys was 0.73 +/- 0.73 years. CONCLUSIONS: The standards of dental maturation described by Demirjian et al. (1973, 1976) may not be suitable for British children.

Age Determination by Teeth↗
PubMed1997

The establishment of current opinion within consultants in paediatric dentistry in the UK for the taking of dental radiographs of children.

There is an increasing realization that every effort should be made to minimize the exposure to ionizing radiation of patients and members of the dental team. There are, however, few published guidelines to assist the general practitioner in deciding whether or not radiographs are needed. There is even less information concerning the taking of dental radiographs of children. Using the Delphi Technique this study set out to seek a consensus amongst Consultant Paediatric Dentists (n = 36) working in the UK as to when dental radiographs should and should not be taken of children cared for within general dental services. A two-stage questionnaire was used and a response of 94% and 76% was obtained in the first and second questionnaire respectively. A consensus view was reached regarding whether or not radiographs should be taken in a series of 17 specific clinical situations.

Child↗
PubMed1996

The effects of unilateral and bilateral chewing, empty clenching and simulated bruxism, on the masticatory-parotid salivary reflex in man.

In man, parotid flow has been recorded, using modified Lashley cups, in response to mechanical stimulation of the teeth by repeated chewing and clenching manoeuvres. The rectified and integrated masseter electromyographic activity was used as an indirect measure of the stimulus intensity where necessary. Following the observation that "empty clenching' failed to evoke a parotid salivary response, a series of three experiments has been undertaken to address the following questions. (1) Is a lateral component of force required to evoke a flow during empty clenching? (2) Does contralateral inhibition of salivary secretion explain this observation? (3) What is the threshold for the masticatory-salivary reflex? The results suggest that: (i) empty clenching together with a lateral component of force does not result in a secretion above resting flows; (ii) there is no evidence for the existence of contralateral inhibition of salivary secretion; and (iii) the threshold for the masticatory-salivary reflex is lower than 5% of comfortable chewing forces. We are still unable to offer an explanation for the lack of parotid secretion during empty clenching.

Bruxism↗