4. Dental caries begins at a very early age.

5. Dental Caries prevalence studies conducted in developed countries showed a decrease in the frequency and severity of disease..

7. Bacteria Diet Tooth Time

8. oral hygiene frequent consumption of carbohydrates previous experience of caries, severity of the lesions

9. age, characteristics of the saliva, inexistence fluoride therapies, socio-economic factors. and others...

10. Deficiencies in Oral Hygiene accumulation of dental plaque reducing the clearing of acids formed by microorganisms facilitate demineralization of the hard tooth tissues prevent remineralization of demineralized surfaces

11. Determine the prevalence of dental caries in patient attended the Conservative Clinic of Aden Faculty of Dentistry. Determine the severity of dental caries in patient attended the Conservative Clinic of Aden Faculty of Dentistry.

12. To establish a relationship between the prevalence of dental caries, gender and age. To establish a relationship between the severity of dental caries and oral hygiene.

13. Type of study : Observational Retrospective..

16. Healthy0 only in occlusal surfaces1 buccal fissure of lower molars, palatal fissure of upper molars or upper incisors 2 proximal surfaces of molars and premolars3 proximal surfaces of anterior teeth4 smooth surfaces of posterior teeth5 6

18. TOTAL 1<19 28.8 20-2425 25-3926.9 40-5916.5 602.7

19. DMFTOTALMALEFEMALE < 20 4.044.78 4.3 4.3 20 - 24 4.33.353.98 25 - 39 3.444.43.91 40 - 59 6.676.546.58 60 and + 9.251610.6 TOTAL4.444.964.66 The DMFT index at age 12 in 1990 was 3.1.

26. 1.Dental careis showed a high prevalence in this group of patients 2.The highest value of DMFT index was observed in patients with 60 years old and more 3.Females were more affected than males 4. Moderate severity of carious lesions was found in this study 5. Pateints with bad oral hygiene developed highest severity of dental careis

27. The very high level of caries prevalence and dental treatment needs revealed by the present study demonstrate the necessity to target oral health services towards community-directed prevention and oral health promotion, in order to improve the oral health status of yemeni society.

28. It is necessary for oral health professionals to recognize the significance and importance of preventive activities. An organized intervention, leading towards improving dental status through increasing the populations knowledge, attitude, and behavior to dental care is recommended.