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Family functioning and oral health-related quality of life among children following dental treatment under general anaesthesia

A 2020/2021 Summer Studentship research project

Student: TBC
Supervisors: Arun Natarajan, Professor Murray Thomson
Sponsor: Canterbury Branch of the New Zealand Dental Association


Early childhood caries (ECC) is a chronic highly prevalent non-communicable disease and the number of affected children for treatment is steadily increasing every year. The number of children being managed under general anaesthesia (GA) for comprehensive dental treatment has been steadily increasing over the last twenty years [Whyman et al. 2012]. Research has shown significant improvement in Oral Health-Related Quality of Life (OHRQoL) to occur after dental treatment under GA (DGA) for ECC. However, the role of family functioning, the sustainability of the effect of DGA on the changes in OHRQoL and DGA-associated changes in impact prevalence all need to be investigated. The proposed study will use self-administered short-form P-CPQ (8 item) and 8-item family impact scale (FIS) questionnaires. Parents/caregivers of children who will be undergoing DGA will complete the questionnaires at baseline and subsequently, at 4 weeks, 6 months and 1 year after the operation. Parents will also complete the McMaster family functioning
scale at baseline. Baseline and follow-up P-CPQ and FIS scales scores will be compared. Negative binomial regression modelling or Poisson regression modelling will be used to model follow-up scale scores to determine the effect of family functioning. The sustainability of OHRQoL improvement will be determined by comparing effect sizes across the 3 follow-ups.


The project will assess the changes in OHRQoL among young children with early childhood caries (ECC) who will undergo dental treatment under GA using the recently developed and validated short form P-CPQ-8 and 8-item family impact scales (FIS). The findings of the study will provide evidence to support the benefits of dental treatment for ECC under GA, and clarify the influence of family functioning in the efficacy of the care provided. Most importantly, the project will provide new information on sustainability of the effect of DGA on changes in OHRQoL and DGA-associated changes in impact prevalence.


The proposed research will be a collaborative project between healthcare professionals from the Department of Oral Sciences (University of Otago) and the dental unit at Christchurch hospital (Canterbury District Health Board). The data will be collected at the paediatric dentistry unit of Christchurch hospital. Ethical approval for conducting the project will be obtained from the Human Ethics Committee of the University of Otago.

The participants will be a consecutive clinical convenience sample of the parents/caregivers of children receiving dental treatment under GA. Informed consent for joining the study will be obtained from the parents/caregivers before their participation in the study. For an expected effect size of 0.9 (the mean effect size based on Thomson, 2016), an alpha value of 0.05, a beta value of 0.2, and an estimated standard deviation of 5.4 for the change in FIS-8 score, we will need 283 participants. However, in order to compensate for some loss to follow-up, a sample of 350 participants will be recruited.

Inclusion criteria

  1. Parents of children aged between 12 months and 10 years of age with caries and passing through elective dental general anaesthesia pathway at the Christchurch hospital (Canterbury District Health Board) for treatment including extractions and/or restorations in their primary dentition.

Exclusion criteria

  1. Parents of children aged above 10 years of age
  2. Children with caries in permanent teeth
  3. Children with dental enamel defects in primary or permanent teeth ( can include pt with hypomin molars and also has decayed teeth needing treatment. Exclude hypomin molars require extraction only)
  4. Children with special health care needs (can include pt with ADHD, Autistic spectrum disorder but not pt with cerebral palsy etc)
  5. Families not interested to participate in the study
  6. Families needing interpreter services (We can include parents who do not need interpreter and can understand the questionnaire) Study procedures Self-administered short-form P-CPQ (8 item) and 8-item family impact scale (FIS) questionnaires [Thomson et al. 2013] will be used to gather the data.

The parents/caregivers will be asked to complete the first questionnaire while the child is undergoing the dental treatment under GA. The follow-up questionnaires will be posted to parents/caregivers to complete at 4 weeks, 6 months and 1 year after the operation. The questionnaire will be sent through mail to them 1–3 weeks later (with a self-addressed and postage-paid envelope) or sent through email if they have provided one at the time of the study. If this would not be returned within 1 month, a second copy will then be mailed, and a reminder telephone call will be made. No questionnaires will be completed by telephone interview [Malden et al. 2008]. Parents will also complete the McMaster family functioning scale at baseline [Boterhoven de Haan et al. 2015].


The demographic data of the children to be treated under GA (including age, gender, and ethnicity) will be gathered from their respective clinical records. Additionally, information on the child’s oral condition and treatment provided will also be gathered.

The data on ethnicity will be recoded into the following five groups: European, Maori, Samoan, other Pacific Islanders and Other [Malden et al. 2008]. The treatment data to be collected will include the number, surfaces and materials of restorations that will be placed, and the number of extractions that will be undertaken. The DMFS/dmfs index will not be used, because we expect (based on our previous experience) that many of the children will be in the mixed dentition, and that may complicate its application in this age group.

Sociodemographic data will be collected, with socioeconomic status (SES) being determined by parental occupation and categorised using the NZ Socio-economic Index (NZSEI). The household’s street address will also enable a NZDep01 index score to be allocated to each participant after geocoding. Using both methods will provide both an individual- and an area based measure of SES, and a more comprehensive picture of any inequalities which exist.

Oral health-related quality of life The OHRQoL instruments to be used in this study will be the short-form P-CPQ (8 items) and 8-item family impact scale (FIS) questionnaires (Thomson et al. 2013). For the FIS, the parental/family activity domain provides four of the items, with the parental emotions and family conflict domains each providing two items. The items on the scale will help to collect data on the frequency of impacts. For example, one of the questions in baseline questionnaire will ask ‘In the past 3 months, how often has your child had….pain in the teeth, lips, jaws or mouth?’, while the questionnaire during the follow-up will ask ‘Since the operation to fix their often has your child had pain in the teeth, lips, jaws or mouth?’. The responses will be scored using a fivepoint Likert scale (response options: 0, ‘Never’; 1, ‘Once or twice’; 2, ‘Sometimes’; 3, ‘Often’; 4, ‘Every day or almost every day’). In addition to these, a ‘Don’t know’ response option will also be provided, and scored as 0; as this has been reported in previous research works not to change the overall findings significantly. Additionally, it also avoids missing valuable information which might occur if complete data from participants with nonresponse to some items were excluded.

In the present study, the effect of family functioning on changes in OHRQoL after dental treatment under GA will be studied with the McMaster scale. Data analysis The analysis will begin with confirming that the psychometric properties of the three self-report scales are appropriate and up to standard, after which scale scores will be computed, along with the prevalence of one or more impacts on each scale.

Following this, an attrition analysis will be done, comparing the baseline sociodemographic characteristics and scale scores of those who were followed up with those who were lost to follow-up. The hypotheses will then be tested. These are described below:

  1. For hypothesis one, baseline and follow-up P-CPQ and FIS scales scores will be compared, with the change in score computed as the latter subtracted from the former. For each scale, an effect size will be calculated by dividing the change score by the standard deviation of the mean baseline score.
  2. For hypothesis two, the change in prevalence of P-CPQ and FIS impacts will be determined and tested for statistical significance using the McNemar test.
  3. For hypothesis three, we will use a score of greater than 2 scale points on the GF12 subscale of the McMaster Family Assessment Device (Boterhoven de Haan et al, 2015) to identify families with unhealthy functioning (those with lower score will be categorised as having healthy functioning). This will enable us to compare the effect sizes for the P-CPQ and FIS scale score improvements between those two family types. We will then use negative binomial regression modelling (or Poisson regression modelling, depending upon the distribution of scale scores) to model follow-up scale scores, controlling for baseline scale score, GF12 scale score and sociodemographic and baseline oral disease characteristics to determine whether the effect of family functioning persists once confounders have been controlled for.
  4. For hypothesis four, baseline and follow-up P-CPQ and FIS scales scores will be compared for the two groups i.e extractions only or restorations and extractions provided under GA. The change in prevalence of P-CPQ and FIS impacts between the two groups will be determined and tested for statistical significance using the McNemar test.

Student researcher’s component of the study

Recruiting participants for the study, entering data from the questionnaire, sending out follow up questionnaires, working closely with research assistant of the project in reducing dropouts for the follow up study, and experiencing the research component involved in recruiting participants, collecting data, recording, reporting information.

Student prerequisites

4th year BDS Student from Otago, Dunedin.