EFFECT OF LIGHT CURING UNIT CHARACTERISTICS ON LIGHT INTENSITY OUTPUT, DEPTH OF CURE AND SURFACE MICRO-HARDNESS OF DENTAL RESIN COMPOSITE.

BACKGROUND: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. OBJECTIVE: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-hardness (SMH) of dental resin composite. DESIGN: Laboratory based, cross-sectional analytical study. SETTING: Public and private dental clinics in Nairobi, Kenya. SUBJECTS: Eighty three LCUs which were in use in private and public dental health facilities in Nairobi, Kenya and resin composite specimens. RESULTS: Of the 83 LCUs studied, 43 (51.8%) were Light Emitting Diodes (LEDs) and 39(47.0%) were Quartz-Tungsten-Halogen (QTH) and 1 (1.2%) was Plasma Arc Curing (PAC) light. Mean light intensity for QTH and LED lights was 526.59 mW/cm2 and 493.67 mW/cm2 respectively (p=0.574), while the mean DOC for QTH lights was 1.71 mm and LED was 1.67 mm (p=0.690). Mean Vickers Hardness Number (VHN) for LED was 57.44 and for QTH was 44.14 (p=0.713). Mean light intensity for LCUs < or = 5 years was 596.03 mW/cm2 and 363.17 mW/cm2 for units > 5 years old (p=0.024). The mean DOC for the two age groups was 1.74 mm and 1.57 mm respectively (p=0.073). For SMH, the < or = 5 years and >5 years age groups gave a mean VHN of 58.81 and 51.46 respectively (p=0.1). On maintenance history, the frequency of routine inspection, duration since the last repair/replacement of a part or other maintenance activity and the nature of the last maintenance activity were determined and were not found to have influenced the light intensity, DOC and SMH. CONCLUSION: The LCU age has a statistically significant influence on its light intensity (p=0.024) while the type and maintenance history have no significant influence on its light intensity and composite DOC and SMH (p=0.574, p=0.690, p=0.713 respectively).

EFFECT OF LIGHT INTENSITY ON THE CURE CHARACTERISTICS OF PHOTO-POLYMERISED DENTAL COMPOSITES.

OBJECTIVE: To determine the light intensity emitted by light curing units (LCUs) and its effect on the cure characteristics of composites polymerised with it. DESIGN: A laboratory based cross sectional study. SETTING: Public and private dental clinics in Nairobi, Kenya. RESULTS: Thirty five (42.17%) LCUs produced light of intensity ≤300mWcm⁻² while 43 (51.8%) LCUs had their intensities between 300 and 1200mWcm⁻². Mean DOC and surface hardness for the 0-300mWcm⁻² LCUs was 1.34mm and 46.60VHN respectively. The mean DOC increased steadily from the lowest intensity group (1.34mm) to the 1200-15OOmWcm⁻² group (2.32 mm) and then declined to 1.98mm for the 1500-1800mWcm⁻² group. Statistical analysis showed significant differences in the mean DOC (p=0.000) and surface micro-hardness (p=0.002) for the different intensity groups. CONCLUSION: Light intensity output of LCUs has a significant influence on the cure characteristics of dental composites with both DOC and surface micro-hardness increasing with increase in light intensity up to 1500mWcm⁻².

INTERNAL ROOT MORPHOLOGY IN MANDIBULAR FIRST PERMANENT MOLARS IN A KENYAN POPULATION.

OBJECTIVE: To determine the internal root morphology and gender variations in mandibular first permanent molars in a Kenyan population. DESIGN: In vitro descriptive cross sectional study. SETTING: School of Dental Sciences, University of Nairobi RESULTS: The mesial root of mandibular first molars had two canals in 96.3% of the teeth in both males and females and-type IV canal configuration was most prevalent in the mesial root. The distal root of the mandibular first molar had one canal in 57.7% of the teeth in males and females. There were significant gender variations in the number of canals and canal configurations in the distal root. Two canals were more prevalent in females (53.6%) compared to males (30.4%) and a single canal was more frequent in males (69.6%) compared to females (46.4%) (P=0.001). Canal types 1, 11 and IV were the most frequent in the mandibular distal root. The gender variation in the frequency of canal types I, II and IV in the distal root was statistically significant (P=0.001). CONCLUSION: Most of the mandibular first molars have three canals (56%). Two canals in the distal root are more frequent among females (53.6%) compared to males (30.4%).

Effect of health education on knowledge and oral hygiene practices of persons living with HIV in Nairobi, Kenya.

OBJECTIVE: To assess the effect of oral health education on knowledge and oral health seeking behaviour of persons living with HIV/AIDS (PLWHA). METHODS: Quasi-experimental study design conducted among 195 Persons living with HIV/AIDS attending two Comprehensive Care Centres (CCC) at the Kenyatta National Hospital (intervention group) and Mbagathi district hospital (non-intervention group) in Nairobi Kenya. The participants were selected using systematic random sampling method and data collected using a questionnaire. Data was collected at baseline, at three months (review 1) and at six months (review 2). RESULTS: There was a significant change in oral health knowledge for KNH participants. However, no significant change in oral knowledge was recorded for MDH participants. The proportion of participants who brushed their teeth at least twice a day increased significantly from 52% to 88% for KNH. The proportion of those who had brushed the previous evening increased from 47% to 83.2%. There was no significant change in the proportion brushing at least twice a day among the non-intervention group. There was a significant association between change in knowledge and change to brushing at least twice a day among the intervention group. CONCLUSION: Oral health education led to improved oral health knowledge and oral hygiene practices among PLWHA.

Nutritional and oral health status of an elderly population in Nairobi.

OBJECTIVE: To determine the nutrition and oral health status of elderly persons in Nairobi, Kenya. DESIGN: A cross-sectional study. SETTING: Households in Dagoretti Division of Nairobi. SUBJECTS: Two hundred and eighty nine persons (29.8% males and 70.2% females) aged 45 years and above were assessed. RESULTS: The level of malnutrition using the mid upper arm circumference was 18.8% while by body mass index was 11.4%. Of the population assessed, 46.4% had normal nutritional status while 40.9% were overweight, with more females (48.0%) than males (25.9%) being overweight. The study established that many of the elderly persons suffered from dental problems, especially periodontitis with 89.9% having dental plaque, calculus 85.6%, gingival recession 82.5% and bleeding gums 77.4%. The decayed index missing and filled teeth, was 7.173 with 19.7% caries free, 51.9% reported tooth mobility and edentulousness was common. CONCLUSIONS: Under-nutrition, obesity and dental problems are issues of concern among the elderly. There is need to develop policies that will look into the nutrition and dental health of the elderly in order to improve their welfare.

Oral hygiene practices and risk of oral leukoplakia.

OBJECTIVE: To determine the influence of oral hygiene habits and practices on the risk of developing oral leukoplakia. DESIGN: Case control study. SETTING: Githongo sublocation in Meru District. SUBJECTS: Eighty five cases and 141 controls identified in a house-to-house screening. RESULTS: The relative risk (RR) of oral leukoplakia increased gradually across the various brushing frequencies from the reference RR of 1.0 in those who brushed three times a day, to 7.6 in the "don't brush" group. The trend of increase was statistically significant (X2 for Trend : p = 0.001). The use of chewing stick as compared to conventional tooth brush had no significant influence on RR of oral leukoplakia. Non-users of toothpastes had a significantly higher risk of oral leukoplakia than users (RR = 1.8; 95% confidence levels (CI) = 1.4-2.5). Among tobacco smokers, the RR increased from 4.6 in those who brushed to 7.3 in those who did not brush. Among non-smokers, the RR of oral leukoplakia in those who did not brush (1.8) compared to those who brushed was also statistically significant (95% CL = 1.6-3.8). CONCLUSION: Failure to brush teeth and none use of toothpastes are significantly associated with the development of oral leukoplakia, while the choice of brushing tools between conventional toothbrush and chewing stick is not. In addition, failure to brush teeth appeared to potentiate the effect of smoking tobacco in the development of oral leukoplakia. RECOMMENDATIONS: Oral health education, instruction and motivation for the improvement of oral hygiene habits and practices; and therefore oral hygiene status, should be among the strategies used in oral leukoplakia preventive and control programmes.