No abstract

Tongue pressure data taken from healthy subjects during normal oral activities such as mastication, speech and swallowing are providing us with new ways of understanding the role of the tongue in craniofacial growth and function. It has long been recognized that the sequential contact between the tongue and the palate plays a crucial role in the oropharyngeal phase of swallowing. However, because the focus of most research on intraoral pressure has been on the generation of positive pressure by the tongue on the hard palate and teeth, generation and coordination of absolute intraoral pressures and regional pressure gradients has remained unexplored. Ongoing research in our laboratory has uncovered highly variable individual pressure patterns during swallowing, which can nonetheless be divided into four stages: preparatory, primary propulsive, intermediate and terminal. These stages may further be sub-classified according to pressure patterns generated at the individual level as tipper or dipper patterns in the preparatory stage, roller or slapper in the primary propulsive and monophasic or biphasic during the intermediate stage. Interestingly, while an increase in bolus viscosity can result in significant changes to pressure patterns in some individuals, it has little effect in others. Highly individual responses to increased viscosity are also observed with swallowing duration. The above, together with other findings, have important implications for our understanding of the aetiology of widely differing conditions such as protrusive and retrusive malocclusions, dysphagia and sleep apnoea, as well as the development of novel food products.

Abnormal swallow patterns have been associated with specific dentofacial traits, such as an anterior open bite, but the cause-effect relationship between swallowing and malocclusion remains highly controversial. The aim of this research was to determine the effects of acute change in occlusal vertical dimension (OVD) on intraoral pressure swallow patterns and perioral electromyographic activity (EMG) during swallowing. Ten volunteers (five female, five male; 27-32 years) repeated standardised swallowing tasks as the OVD was progressively increased using mandibular trays of different heights. Standardised swallowing tasks were performed repetitively with each tray in place. Individual swallowing waveforms were quantitatively and qualitatively analysed. Peak pressure, swallow duration, time to peak pressure and lip EMG peak activity were assessed for each swallow. Data were analysed using mixed-model analysis. As OVD increased, lip peak pressure during swallowing increased almost threefold (+2·1 kPa; P ≤ 0·001), whereas swallow duration increased by 12·7 per cent (+160 ms; P = 0·01) at lip level and by 26·4 per cent (+270 ms; P < 0·001) at tongue level. Perioral muscle activity during swallows increased by 43·7 per cent (P ≤ 0·01) up to the OVD where resting lip seal was not attainable. Swallowing waveforms varied markedly between individuals, but interindividual waveforms were only minimally affected. The adaptive response and the waveform similarities associated with OVD variation supports the existence of a central control mechanism for swallowing, which may be modified by peripheral inputs.

Background: Numerous studies have indicated that a malocclusion possibly affects young people's well-being and oral health-related quality of life (OHRQoL). Dento-facial aesthetics may influence how people are judged and may elicit social consequences such as bullying and negative comments. The present study aimed to explore the impact of a malocclusion on young New Zealanders who sought subsidised treatment from the Wish for a Smile (WFAS) organisation and to determine their motivation for seeking care. Method: A qualitative thematic analysis of 151 application letters to WFAS from young people (aged 11-18 years) and their caregivers was supplemented by telephone interviews of nine successful and nine unsuccessful applicants to explore their experiences through their own words. Results: In both the letters and the interviews, young people most commonly reported psychological impacts, followed by social and emotional effects associated with their malocclusion. Physical impacts were less commonly reported. In their application letters, caregivers, although at lower frequencies, reported that the young people experienced the same impacts. One caregiver referred to the young person's malocclusion as a temporary disability. Conclusion: For some young people, a malocclusion may lead to social consequences that are disabling. When considering funding options, it is important to note the individual experience and the impact that a malocclusion might have upon the young person's well-being.

Objective: To evaluate and compare the primary surgical outcomes of complete unilateral cleft lip and palate (UCLP) patients in two New Zealand cleft care centres. Methods: This is a retrospective study of two providers of cleft care in New Zealand: Centre A in the North Island and Centre B in the South Island of New Zealand. Pre-orthodontic study models were evaluated from 28 UCLP patients from Centre A with primary surgical repairs performed between 1987–1999 and 31 UCLP patients from Centre B with primary surgical repairs performed between 1984–2000. Dental arch relationships were measured using the Goslon Yardstick. A Goslon score of 1 is considered to be an excellent outcome, whereas a score of 5 is a very poor treatment outcome. Results: Intra- (Kappa: 0.84 – 0.93) and inter-examiner (Kappa: 0.63 – 0.69) reliabilities revealed good to very good agreement between examiners using the Goslon Yardstick. The mean Goslon score for Centre A was 3.5, with no cases in Group 1, five cases in Group 2 (17.9 per cent), nine cases in Group 3 (32.1 per cent), 11 cases in Group 4 (39.3 per cent) and three cases in Group 5 (10.7 per cent). The mean score for Centre B was 3.1, with one case in Group 1 (3.2 per cent), nine cases in Group 2 (29.0 per cent), eight cases in Group 3 (25.8 per cent), 11 cases in Group 4 (35.5 per cent) and two cases in Group 5 (6.5 per cent). There were no statistically significant differences between the two centres (p > 0.05). Conclusions: The outcome scores from the two cleft centres, based on historic records, were disappointing and higher than expected. It is recommended that a review of primary surgical protocols be implemented to ensure outcomes comparable with international standards. The results provide useful benchmarks for future comparisons of treatment.