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Biomedical subjects

M J Trenouth

Publications and source records attributed to M J Trenouth.

At least 19 recordsLinked to original sources
PubMed2002

Proportional changes in cephalometric distances during Twin Block appliance therapy.

The aim of the study was to evaluate the cephalometric changes produced by the Twin Block appliance. Lateral cephalometric radiographs were taken before and after Twin Block appliance treatment on 30 consecutive patients (14 male, 16 female, mean age 12 years 6 months). Published normative data tables were used to produce control data, which were individually matched to the test group for age, sex, and treatment time. Alteration in shape was assessed by measuring percentage change in linear dimensions as opposed to change in cephalometric angles used in previous investigations. The differential average percentage change was calculated by subtracting the control value from the Twin Block value. Clinically significant changes (2 per cent and greater) were found in lower anterior (6.6 per cent) and posterior (4.6 per cent) face heights, upper incisor to maxillary plane (4.9 per cent), i.e. upper incisor retraction, and increase in mandibular length (Co-B 3.3 per cent, Co-Po 2.6 per cent, Ar-B 3.5 per cent, Ar-Po 2.2 per cent).

Adolescent↗
PubMed2001

A cephalometric evaluation of the Biobloc technique using matched normative data.

PATIENTS AND METHOD: The outcome of Biobloc treatment was evaluated on 35 patients, 13 male, 22 female, with Class II, Division 1 malocclusions. Cephalometric radiographs were taken before and after treatment. A control group was generated from published normative data in such a way that each treated case was matched individually for age, sex and treatment time. The cephalometric change during treatment was compared to the natural growth change in the matched control group using a Mann-Whitney U-test. The treatment effect was calculated by subtracting the natural growth change from the treatment change. This was then compared to twice the method error to see if the treatment change was clinically significant. RESULTS: There was both a statistically and a clinically significant reduction in overjet (p < 0.001), overbite (p < 0.001) and angle ANB (p < 0.001) with an increase in angle SNB (p < 0.001). None of the other cephalometric parameters measured showed a significant change except for upper incisor proclination (p < 0.05) and ArGoMe angle (p < 0.05) but these were not clinically significant.

Adolescent↗
PubMed2000

Cephalometric evaluation of the Twin-block appliance in the treatment of Class II Division 1 malocclusion with matched normative growth data.

Cephalometric radiographs were taken before and after treatment with the Twin-block appliance on 30 consecutive patients with Class II Division 1 malocclusions. A control group was generated from published normative data such that each treated case was matched individually for age, sex, and treatment time. The cephalometric change during treatment was compared to the natural growth change in the matched control group using a Mann-Whitney U-test for statistical significance. The treatment effect was also calculated by subtracting the natural growth change from the treatment change. This was then compared to twice the method error to see if the treatment change was clinically significant. There was both a statistically and clinically significant reduction in overjet, angle ANB, increase in angle SNB, and mandibular length together with a reduction in upper incisor angle. None of the other cephalometric parameters measured showed a significant change.

Case-Control Studies↗
PubMed1999

Relationship of the functional oropharynx to craniofacial morphology.

The association between the functional oropharyngeal airway (defined as the minimal sagittal dimension at right angles to the airstream) and craniofacial morphology was investigated using 16 craniofacial variables taken from lateral cephalometric radiographs. The sample consisted of 70 subjects (31 males and 39 females) 10 to 13 years of age. There was no difference in ages between males and females, and no correlation with age except upper face height. Oropharyngeal airway was positively correlated with length of the mandible (Gon-Men), the distance between the third cervical vertebra and the hyoid bone (C3-Hy), and cranial base angle (NSBa). Although short mandibular length is a characteristic finding in patients with obstructive sleep apnea, none of the subjects in this study had this diagnosis.

Adolescent↗
PubMed1999

Differences in cephalometric reference values between five centres: relevance to the Eurocleft Study.

Cephalometric data from five different geographical areas (Oslo, Manchester, London, Nijmegen, and Michigan) were compared. The angles SNA, SNB, and ANB were taken from published tables in the form of mean, standard deviation (SD) and number in the sample, divided up by age and sex. Angles SNA and SNB were significantly different among centres on univariate analysis. The Oslo data showed 23 instances in which they differed significantly from the other data, London 16, Manchester 11, Nijmegen 11, and Michigan 7. Multivariate analysis using Penrose distances were Oslo (2.04), Manchester (1.39), London (0.93), Nijmegen (0.80), and Michigan (0.66). The sums of the Mahalanobis distances were Nijmegen (3.60), Oslo (3.10), London (2.80), Manchester (2.25), and Michigan (1.49). As these results probably reflect racial and genetic differences, these must be taken into account when international comparisons are being made, as in the Eurocleft study.

Age Factors↗
PubMed1996

Questionnaire evaluation of feeding methods for cleft lip and palate neonates.

A questionnaire evaluation was undertaken of feeding methods used by the mothers of 25 neonates with cleft lip and/or palate. Most parents had problems feeding their babies, both with the quantity of food taken and especially with the time taken to feed; even after a period of 2 months over a quarter were still having problems with the quantity of feed and a third had not established a regular feeding pattern. Just over a half needed to change the feeding method from the one with which they started. Twelve of the 25 mothers tried to breast-feed but none of them was successful. The Haberman feeder was the most popular, being used by 18 mothers. An acrylic feeding plate was considered to be helpful by 6 of 11 mothers of babies with complete clefts but by only 1 of 9 mothers of babies with secondary palate clefts. Almost all the mothers were dissatisfied with the information they had received while in hospital and with the back-up when they went home.

Bottle Feeding↗
PubMed1996

Alteration in facial shape in the anencephalic human foetus.

Tracings were produced from frontal radiographs of 11 anencephalic foetuses. These were compared analytically with standards derived from 60 normal foetuses. The anencephalics showed a marked reduction in the relative size of the cranium with considerable flattening of the calvarium, which is characteristic of the condition. The orbits were more medially placed, being closer together and somewhat higher in position that the normal foetal outline. The right and left mandible were more elongated with an increase in the intermaxillary space. The condyles were more medially positioned and were closer to the orbits than in the normal outlines. In normal growth, expansion of the brain flattens the cranial base, displacing the nasomaxillary segment forwards. In anencephally this does not happen so that the nasomaxillary segment rotates in an antero-inferior postero-superior direction along with the intermaxillary space and mandible. This produces a significant lengthening of the face accompanied by narrowing in the region of the cranial base relative to the normal outline.

Anencephaly↗
PubMed1991

Relative growth of the human fetal skull in width, length and height.

Linear measurements of the width, length and height of the face and cranium were made on 60 fetuses of 49-212 mm crown-rump length. Absolute growth rate was derived from the slope of the regression line of dimensional length against time. There was a high correlation between absolute growth rate and mean dimensional length (r = 0.995; p less than 0.001). The relative growth rate was calculated by dividing the absolute growth rate by the mean dimensional length. Change in shape was measured by the relative increase or decrease in dimensional length once the outlines were normalized to an equal area to eliminate the effect of size. Change of shape correlated highly with relative growth rate (r = 0.95; p less than 0.001). Relative growth rates provide a reliable indication of change in shape, unlike absolute growth rates, which are mainly influenced by size. Measurement of relative growth rates showed an increase in cranial length greater than height greater than width and facial length greater than width greater than height.

Age Determination by Skeleton↗
PubMed1989

The stability of anatomical and centroid reference points in cephalometric analysis.

Cephalometric records of 60 fetuses were combined on a coordinate reference grid to measure the statistical spread of the outlines. When centroid instead of anatomical points were used for superimposition of records, the spread of the outlines was reduced dramatically, being statistically significant (p less than 0.001). The centroid is a mean point being less variable and preferable to anatomical points commonly used for comparing successive cephalometric records.

Cephalometry↗
PubMed1989

A functional appliance system for the correction of class II relationships.

A technique is described for the correction of Class II malocclusion involving a functional appliance and consisting of three phases. 1. Adjustment of posterior arch width and dental alignment, using semi-rapid maxillary expansion by means of an upper removable appliance, to co-ordinate the anticipated positions for the arches. 2. Correction of the Class II dental relationships using a modification of the twin-block functional appliance. 3. Retention, using an upper removable appliance with a very steep anterior bite plane. The technique is illustrated by a case report.

Activator Appliances↗
PubMed1988

A quantified comparison of craniofacial form with nasal respiratory function.

Rhinomanometry provides a means to quantify the nasal airway in terms of its conductive efficiency by use of the inverse or resistance to airflow. In samples of 21 male and 26 female subjects, nasal airway resistance was compared with a number of form measurements and the coefficients of correlation were calculated. Statistical significance was found in some of the relationships with nasal airway resistance, particularly the maxillary-mandibular plane angle, the palate-tongue distance, the palatal width, and the facial index.

Adolescent↗