Formal approval

Approval for the study was sought and obtained from the Ministry of Education (Saudi Arabia), the President General for Girls Education and the Dental College (App. 3).

5.6 Method

5.6.1 Sample selection and criteria for selection of children

Children aged 11-16 years who were attending the Al-Amal Institute (for children with hearing impairment) and Al-Noor Institute (for children with visual impairment) formed the study group. The study group sample comprised of 77 VI and 210 HI children. The control group comprised all children aged 11-16 years (494) attending public schools around Riyadh selected by the Ministry of education and Girls Education office.

The Ministry of Education selected two primaries and four secondary public males schools in Riyadh, which reflected the social class of the population. A list of all female children attending primary and secondary levels was obtained from the President General for Girls Education. The Girls Education office on a similar basis as the male selected two primary and four secondary female schools.

All the female children were examined at their schools. The sensory impaired males were examined at their school while the control group at the King Saud University, Dental College. The Ministry of Education provided buses for transportation to the Dental College. The control sample size was designed to

explaining the purpose of the study, requesting eonsent to their child being examined and asking them to complete a questionnaire. Also, a eonsent form was sent to the male family asking their permission to transport the child to the dental college.

5.6.2 Clinical examination

The study children were examined at the school check-up room under standardised lighting condition using a Daray light (dental model order no. SL400/222 with "G" clamp). The control group female children were examined at the school social worker room and the male children at the paediatric clinic. Each child was examined supine with the examiner seated behind the child. The examiner worked with a trained recorder. Teeth and surfaces were examined in a standard order and their status recorded. A pair of sterile gloves and a set of sterilised instrument were used for each subject. A blunt probe was used to remove any gross debris from the teeth. The teeth were not cleaned further or dried prior to examination.

5.6.3 Method of collecting data

The methods for the clinical examination were those of the British Association for the Study of Community Dentistry (BASCD) for basic oral health surveys (Child Dental Health Surveys, 1995) (App. 4). Each surface was charted for caries, trauma, gingival conditions, and developmental defects of enamel.

The medical history for the study group was obtained from their medical record eoneeming their cause of disability, time of onset, degree of sensory loss and their I.Q (App. 5).

5.6.4 Measurement of social classes

Social class in western countries are often based upon the level of education of the head of household. However, in countries which are in transition such as Saudi Arabia, the classification of social class is difficult because of the dramatic changes in culture and infrastructure. Alternatively, the level of income in the

Saudi population can act as a factor in classifying the social class of the sample. According to this, the social class in this study was estimated by the father’s occupation and the mother's education as utilised in the Oral Health Survey of Saudi Arabia in 1991 (Al-Shammary et a l, 1991). The social class according to father's occupation can be divided into 3 groups; Professionals (doctors, professors, architects) and Businessman as upper class. Governmental (military and governmental workers) as middle class. Manual (manual workers, farmers) and Unskilled (unskilled workers and others including students, the unemployed and those not indicating any occupation) as lower class.

The social class according to mother's education can be divided into 3 groups; Degree level (University and postgraduate) as upper class. Secondary level of education as middle class, and finally primary level as lower class.

5.6.5 Parents questionnaire

For each child a questionnaire was sent to the parent through the school administration. The questionnaire included questions modified from the Child Dental Health Survey (O'Brien, 1994; Q8, 9, 10, 11, 12 and 13) looks at child dental attendance (App. 9).

Information was gathered with regard to the father's occupation and mother's educational achievement. The parents were asked with regards to their views on their child's teeth, and their attitude to the child having orthodontic care.

5.6.6 Statistical Analysis

All the data were collected and entered into the SPSS program for analysis. Both descriptive and analytic approaches were used in the data analysis. Tests of the association between oral health status and single variables were carried out using the Chi square test. A p-value of < 0.05 was considered statistically significant. A non-parametric test was used to compare between continuous data values. For comparison of the sample proportions standard normal distribution (SND)

carried out using logistic regression analysis to test the association of various variables to the occurrence of disease. The odds ratios and 95% confidence intervals were used to compare the relative risk ratio of the studied background factors for the occurrence of caries and the periodontal condition.

5.7 Results

The results drawn from the clinical examination of 494 control children, 77 VI and 210 HI children are summarised in Tables 5.1 - 5.24

5.7.1 The sample profile

A total of 494 control children were examined (258 female and 236 male), 77 visually impaired (VI) children (38 female and 39 male) and 210 hearing impaired (HI) children (127 female and 83 male) as shown in Table 5.1. The mean age was 12.9 years in the control group, 13.4 in the VI group, and 13.5 in the HI group (Table 5.1). There were 42.1% of controls, 53.2% of VI and 51% of HI children in the primary level of education, and 57.9%, 46.8% and 49% respectively in the secondary level.

The social class of families is summarised in Tables 5.2 and 5.3. Of the total sample, 125 (25.3%) control children, 9 (11.7%) VI children and 16 (7.6%) HI children were from the upper class (professional and businessman). Three hundred and twelve (63.2%) controls, 57 (74%) VI children and 126 (60%) HI children were classified as from the middle classes; and 49 (9.9%) controls, 8 (10.4%) of VI children, and 33 (15.7%) HI children had fathers who were classified as manual to unskilled or other occupations (lower class). Eight (1.6%) controls, 3 (3.9%) VI children and 35 (16.7%) HI children were not classified by social class because of failure to respond. It was noted that the upper class contained more control children than VI or HI children.

139 (28.2%) of the control children, 28 (36.3%) VI children and 61 (29%) HI children had mothers who were educated to primary level. Two hundred and four (41.3%) controls, 20 (26%) VI children, and 45 (21.4%) HI children had mothers whose education was to secondary level. Ninety-five (19.2%) control children, 15 (19.5%) VI children and 22 (10.6%) HI children had mothers whose education included a period of college and sometimes postgraduate study. There was some missing information from mothers of 56 (11.3%) controls, 14 (18.2%) VI children, and 82 (39) HI children.

5.7.2 Caries

The findings at the clinical examination in relation to caries are summarised in Table 5.4, Caries was seen in 572 (73.3%) of the all the study children. It was found in 365 (73.9%) controls, 60 (77.9%) VI children, and 147 (70%) HI children.

5.7.2.1 Total caries prevalence

Similarity in caries prevalence was observed in the three groups. The control group mean DMFT was 2.29 compared to 2.48 for the VI group and 2.11 for the HI group. Caries experience was made up largely of decayed teeth. These made up a DT component for the control group of 1.47 (SD± 1.88) per child out of total DMFT of 64.7%. For VI children, the mean DT was 1.98 (SD± 2.45) per child out of total DMFT of 79.8%; while for the HI children, it was 1.47 (SD± 1.80) per child out of total DMFT of 69.6%.

There was a statistically significant difference {p = 0.030) when the mean DT component was compared between the control group (1.47) and the VI group (1.98), based upon the Mann-Whitney test. There was also a statistically significant difference {p = 0.038) between the VI (1.98) and the HI (1.47) children. However, the DT between the control and HI children was similar. The mean MT of the control group was 0.09 (SD± 0.44), 0.07 (SD± 0.31) of the VI

group and 0.15 (SD± 0.52) of the HI group. It was apparent more teeth had been extracted among HI children compared with the VI or control children.

The mean DMFS varied for the three groups; the control group mean DMFS was 5.10, compared to 7.02 of the VI group and 4.9 for the HI group. Caries experience was made up largely of decayed surfaces. These made up a DS component for control group of 3.39 (SD± 5.84) per child out of a total DMFS of 66.4%. For the VI children, the mean DS was 5.64 (SD± 9.44) per child out of a total DMFS of 80.3%; while for the HI children, it was 3.36 (SD± 5 .37) per child out of a total DMFS of 68.5%.

Treatment levels can be assessed by absolute number of surfaces filled (FS) and by relative treatment percentage, according to the proportion of filled surface (FS) out of total DMFS (FS/DMFS xlOO). The absolute treatment level for the control group was 23.9% in comparison to the VI group (13.9%) and HI group (15.7%). A comparison of the proportion for treatment levels between the control and VI children was significant with SND 5.08 and 6%-14% differences. However, the treatment level between control and HI children, showed significant SND of 5.39 with 6.7%-9.5% differences.

The differences between DMFT and DMFS for the three groups was tested using the Kruskal-Wallis test which was confirmed not to be statistically significant between the control and study children.