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Biomedical subjects

W G Evans

Publications and source records attributed to W G Evans.

At least 19 recordsLinked to original sources
PubMed2005

Gender and race distribution of dental graduates (1985-2004) and first year dental students (2000-2005) in South Africa.

This paper, written at the close of a decade of democracy in South Africa, sets out to analyse the demographic profile of dental graduates from 1985-2004 at the five Faculties/Schools of Dentistry in South Africa. A comparison of the profiles for the pre-democracy (1985-1994) and post-apartheid (1995-2004) periods has been made. The demographic profile of first year dental students from 2000-2005 is also presented. From 1985-1994, most dental graduates were male (79%), but this changed substantially from 1995-2004, with females comprising 46% of those graduating. In the pre-democracy period, more than three-quarters of all graduates were White (78%), decreasing to 46% in the post-apartheid period under review. Black graduates increased from 6% to 24% across the two study periods. Amongst the first year dental student intake from 2000-2005, females comprised 57%. There was an almost equal distribution across the White, Black and Asian groups. Dental faculties/schools have made important strides in transforming the demographic profile of their students. The percentage of Black graduates, however, needs to be significantly increased if it is to reflect the national population. Faculties/schools must further ensure that able students from working class background are identified and considered for acceptance into the undergraduate dental programme, and should then be offered the necessary academic and mentoring support to enable success.

Asian People↗
PubMed2001

Curriculum 2001: a proposal for a new, integrated, dental curriculum at the University of the Witwatersrand.

Recent technological advances and an escalation of knowledge in dentistry have highlighted the need to revise the current undergraduate dental curriculum at the University of the Witwatersrand. This imperative is reinforced on one hand by manifest problems in content, structure and sequencing of the existing curriculum, and on the other hand by the need to urgently address contemporary South African issues. Revision will also offer the opportunity to incorporate modern educational practice and philosophy. This paper proposes that the contents, sequence and duration of the curriculum must be determined by the knowledge demands of dentistry (global issues) as well as by local constraints. It suggests early clinical contact and changes in syllabus content, pedagogy and assessment practices in an undergraduate course of slightly reduced duration.

Curriculum↗
PubMed1997

The relationship between ortho head posture and head posture measured during walking.

Murphy, Preston, and Evans recognized the dynamic nature of head posture and developed instrumentation capable of measuring and recording this posture in a continuous manner. The aim of the current project was to use the newly developed instrumentation to determine whether the difference is statistically significant between the mean natural head ortho posture, measured in a controlled manner, and the mean dynamic head posture obtained during 5 minutes of walking activity in an experimental situation. The mean ortho head posture and the mean walking head posture were measured in each of 30 men. The differences between these two sets of mean head postures were statistically significant (p < or = 0.05). In 23 persons, the mean walking head posture was tipped backward relative to the mean natural head ortho position.

Adult↗
PubMed1996

An evaluation of two methods used to determine the centre of gravity of a cadaver head in the sagittal plane.

A suitable method to locate the centre of gravity of the head is not available at present. Precise location of that centre will help in the understanding of aspects of cranial balance and what effect skeletal changes, following for example orthognathic surgery, may have on head posture. The objective of this research was to use a mechanical (empirical) method, based on accepted laws of physics, to determine the centres of gravity of cadaver heads in the sagittal plane and to compare these positions with those generated by a computer programme. The two methods located the centre of gravity in the same region but at a different position in each corresponding head. These differences were statistically significant (p < 0.01). It is likely that improved computer techniques together with modern three dimensional imaging methods will be able to locate the centre of gravity of a head in a living subject.

Cadaver↗
PubMed1996

Maxillary premolar extraction--a possible link to later periodontal breakdown?

The palatal embrasure angles between the maxillary first molar and adjacent premolar were measured in 60 children who had had orthodontic treatment (29 with premolar extractions and 31 without), and in 20 adults with periodontal breakdown in the palatal embrasure angle area, who had had premolar extractions. Mean angles were orthodontic groups non-extraction 31 degrees, extraction 42 degrees and the adult group, 57 degrees. Statistical analysis showed significant differences between the groups. A wide palatal angle between maxillary first molar and adjacent premolar appears to predispose to periodontal breakdown in the area. Rotation of teeth which open the palatal embrasure angle should be minimized.

Adult↗
PubMed1995

Constrained and unconstrained postures of the mandible--a break with tradition?

Evaluation of detailed electrognathographic recordings of various movements of the mandible (and points on it) suggested interpretations at variance with some traditional concepts. Data previously accumulated from several sources were subjected to critical analysis. An objective was to assess the manner in which two rotations of the mandible influenced its postures during trials of mastication and deliberate lateral excursions. Rotations about a vertical and an antero-posterior axis appear to facilitate a greater functional posturing potential of the mandible than has previously been reported. In most instances the influence of the rotations upon mandibular posture is considerably greater than the size of the recorded angles would suggest. Some of the resulting postures seem to challenge concepts derived strictly from cadaverine anatomy. For example, during mastication the condyle does not simply glide forward and backward relative to the eminence but may be distracted downward away from it for a part of the time. Furthermore, the ability of a subject to effect a considerable variety of mandibular postures challenges traditional reliance upon constrained mandibular movements as a means of evaluating function.

Humans↗
PubMed1995

Cephalometric analysis of a Sotho-Tswana group.

A cephalometric study was conducted on 50 male and 54 female Sotho-Tswana children 11-16 years of age. The subjects were selected for excellence of occlusion and balance of facial proportions. Various analyses, including Steiner, Wits, and McNamara, were used for the evaluations. The mean measurements were compared with those of other Southern African Black groups and Caucasoids. Our study shows that cephalometric analyses for other groups cannot be used with confidence for the Sotho-Tswana people and our data provides norms for them.

Adolescent↗
PubMed1991

The development of instrumentation for the dynamic measurement of changing head posture.

Cranial posture and its possible relationship to the morphology of the skull has been studied in some detail, as have the relationships between cranial posture and such functions as respiration and jaw movements. To date, cranial posture has been assessed mainly with techniques that give static interpretations of the angular relationships between intracranial and extracranial reference lines. The present project was undertaken to develop a system of instruments capable of the continuous measurement and recording of cranial posture for extended periods of time. A number of aspects of this system were tested. The results indicate that the experimental array of instruments measures head posture accurately over a defined range of cranial movement. This new technique should make it possible to measure cranial posture in a more dynamic and physiologic manner.

Adult↗
PubMed1990

Surgical manipulation of the occlusal plane.

With combined surgical repositioning of the maxilla and the mandible, the occlusal plane is usually determined by the autorotation of the mandible. By manipulation of the cant of the maxillary occlusal plane, additional control of the esthetic result is obtained. In the approach discussed in this paper, prime attention is paid to repositioning of the maxilla into the most favorable situation by a deliberate rotation around points that are anterior in the face. The mandible is then surgically adjusted to secure a good occlusion. In this way, the cant of the occlusal plane becomes a priority in treatment planning, rather than simply an inevitable consequence of maxillomandibular surgery. The technique of treatment planning is discussed in detail, and three cases are presented to illustrate the concept. Of special importance is the enhancement of facial esthetics that is offered by the deliberate manipulation of the occlusal plane.

Adolescent↗