DR. KASSIM BISHAR ALASOW

Background: To achieve adequate cure, a resin composite restoration must be
exposed for a specified duration of time to a light of sufficient intensity and the right
wavelength. However, some commonly used light curing units (LCUs) may yield
inadequately cured restorations due to their insufficient light intensity output.
Furthermore, the efficiency of light curing units in dental clinics and the extent to which
dentists practice the recommended maintenance techniques is largely unknown.
Objective: To determine the efficiency of Light Curing Units (LCUs) in dental clinics in
Nairobi, Kenya.
Study design: A laboratory-based, cross-sectional analytical study.
Study area: The study was set in private and public dental clinics in Nairobi, Kenya. A
total of 83 light curing units selected through a convenient sampling procedure were
used.
Materials and methods: The light intensity output of light curing units in dental clinics
was measured using a digital dental radiometer and the result entered in a data
collection form. Each light curing unit was then used to polymerise two cylindrical resin
composite specimens made using custom-made split brass moulds; one measuring
4mm in diameter and 6mm in thickness used to determine the depth of cure (DOC) and
the other 8mm in diameter and 3mm in thickness used to determine the surface
hardness by using a Vickers Hardness tester. Within 6-7 hours of fabrication, the depth
of cure specimens were immersed in a capsule containing 99%- acetone solvent which
was then vibrated in a mixing device. The DOC was calculated from the undissolved
length of the specimen. The surface Vickers Hardness was evaluated by making three
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surface indentations with a diamond indenter using a load of 200g and a dwell time of
15-seconds. A conversion table was used to convert measurements from the diamond
indentations into hardness numbers. The light intensity output and the depth of cure and
surface micro-hardness numbers of the resin composite specimens were then used to
assess the efficiency of each dental light curing unit. Three main components of the
maintenance history of the light curing units, as well as the age and type of the light
curing unit were also recorded.
The data was entered into a computer using SPSS version 12. The independent sample
t-test, one way analysis of variance (ANOVA) with Post Hoc test and Chi-square tests
were used for data analysis. The results were summarized in tables and figures.
Results: Of the 83 LCUs studied, 43(51.8%) were LED and 39(47.0%) were OTH and 1
(1.2%) was PAC light.
LCU type and light intensity output, DOC and hardness: Mean light intensity for OTH
and LED lights was 526.59mW/cm2 and 493.67mW/cm2 respectively (p=0.574), while
the mean DOC for OTH lights was 1.71mm and LED was 1.67mm (p=0.690). Mean
VHN for LED was 57.44 and for OTH was 44.14 (p=0.713). Light curing unit type had no
statistically significant effect on DOC, surface hardness and the intensity of the light.
Effect of age of LCU on light intensity output, hardness and DOC: Mean light intensity
for LCUs ::;5years was 596.03mW/cm2 and 363.17mW/cm2 for units> 5years old. Age
showed a significant effect on light intensity (p=O.024). The mean DOC for the two age
groups was 1.74mm and 1.57mm respectively (p=O.073). For surface micro-hardness,
the ::; 5years and > 5years age groups gave a mean VHN of 58.81 and 51.46
respectively (p=O.1)
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Efficiency of the LCUs: when intensity was used to measure efficiency, 48 (57.8%)
LCUs were efficient and 35 (42.2%) were inefficient. Only the LCU age significantly
affected efficiency by light intensity output (p=O.008). Only 24 (28.9%) LCUs gave
sufficient DOC as opposed to 59 (71.1%), which gave insufficient DOC. Of the units
tested for surface micro-hardness, 15 (25.9%) had adequate surface micro-hardness
while the rest (43 or 74.1%) had inadequate surface micro-hardness. The type of LCU
and its age did not significantly influence efficiency as measured using depth of cure
and surface micro-hardness of the resin restoration.
On the whole, 11 (19%) of the LCUs which had all the three tests of efficiency done
were satisfactory in all the 3 aspects.
Conclusions: Eleven (19%) of the light curing units used in Nairobi dental clinics were
efficient when subjected to a combined light intensity, and composite resin depth of cure
and surface hardness evaluation, and that the type and maintenance history of a LCU
had no significant influence on its efficiency. Age had a significant influence on the light
intensity of the curing units - there was a decrease in light intensity output with increase
in age of the units. There was a non-linear relationship between the light intensity output
of a LCU and the depth of cure and surface micro-hardness of the cured composite.

Objective: To remove or modify fluorotic enamel stains using a combined chemical micro-abrasion and bleaching technique. Design: An in-vivo study was carried out. A sample of 21 participants was randomly selected from patients presenting with brown staining due to flourosis as the chief complaint. Eighty nine teeth were selected based on the Thylstrup-Fejerskov Index [TFI] with a score of 4 as the acceptable maximum. Only upper anterior teeth were included in the study. Setting: The study was undertaken at the University Of Nairobi Dental Hospital, Kenya. Subjects: Patients with an expressed need for treatment of their discoloured teeth who consented to a clearly demonstrated treatment procedure constituted the sample. Results: Enamel discolouration was removed or modified yielding a uniform colour and lustre depending on the initial depth of the stain. All patients appreciated the colour change. Conclusion: A combined chemical micro-abrasion and bleaching technique is a feasible treatment modality in selected cases of enamel fluorosis.

OBJECTIVE: To determine the dental caries experience and knowledge on the causes and preventive measures for dental diseases. DESIGN: A community based cross-sectional descriptive study. SETTING: Elwak sub-district hospital, North Eastern Province, Kenya. SUBJECTS: One hundred and forty one adults who presented themselves during a dental check up at a sub-district hospital and gave written consent. MAIN OUTCOME MEASURES: Dental caries status and knowledge on its causes and preventive measures. The importance of outreach programmes in obtaining information as well as helping to alleviate the pain and suffering caused by dental diseases among communities living in remote areas is also revealed. RESULTS: Of the one hundred and forty one individuals, who were included in the study, 63.1% were women and 36.9% were men. Their ages ranged between 18 and over 65 years. 41.1% were in the 18-24-year age bracket. Regarding the oral health knowledge, 43% did not know any causes of dental diseases while 36%, 17% and 12% knew that diet, "dirt" on teeth and bacteria were possible causes, respectively. Fifty percent did not know any preventive measures for dental diseases while the rest indicated abstention from the consumption of sugary foods; and only 0.8% mentioned use of fluoridated toothpaste as a preventive measure for dental caries. 56.7% of the subjects were caries free. The mean DMFT for all ages was 3.4. Of those with caries 72.1% were women. CONCLUSION: There is a low level of oral health awareness and a moderately high level of dental caries experience in this community with women apparently carrying the biggest burden of dental caries.