Khat chewing is a deep-rooted habit in Yemen. It was exclusively adult males' habit (17), but it begins to spread among females (4, 15) and children (4). World Health Organization estimated that 70 % to 90 % of men, 30 % to 50 % of women and 25 % of children in Yemen chew khat daily (23). In two separated studies Ali A estimated the prevalence of khat chewing habit in Yemen to be 60.5 % and 61.12 % respectively (2, 3).According to individual authors' observations, khat chewing causes stomatitis that might be secondarily infected (9,17,20). It also causes periodontitis, teeth discoloration and xerostomia (9, 17).There are wide differences in the published epidemiological studies about the effect of khat chewing on oral cavity. Concerning it's dental effect, Hill CM and Gibson A (1987) claimed reduced dental caries among khat chewers (13). Others concluded increased dental carie, especially the cervical ones, teeth staining and attrition in addition to their mobility (5,22). Regarding it's effect on periodontium, it causes gingivitis, periodontitis, periodontal pocket formation and gingival recession (2,5,22). On contrary, other authors proved positive effects of khat chewing, namely less loss of clinical attachment and less pocket depth on the chewing side compared to non-chewing side (13,21) and less plaque and calculus indices among khat chewers compared to non-chewers (14).The aim of this study is to investigate, clinically, the effect of chronic khat chewing on oral mucosae (other than gingiva) and to see if cigarette smoking has additive effect. Material and methodThe study sample consists of 79 Yemeni subjects divided into two main groups, chronic khat chewers (n=54) and control (n=25). The chronocity of khat chewing was defined to be not less than 5 years since starting the habit, not less than 5 days per week and not less than 4 hours per day. The selection criteria of the subjects are male (due to traditional difficulties in finding female sample), systemic diseases-free, no chronic drugs or alcohol users, no shamma (smokeless tobacco) users, do not complain oral mucosal symptoms or use removal dental appliance, For khat chewers, they should chew khat on one side only.The khat chewers group was subdivided according to chewing duration and smoking into six subgroups, Khat chewers for 5-15 years and non-smokers (n=16, mean age=27.1), Khat chewers for 5-15 years and smokers (n=15, mean age=28.5), Khat chewers for more than 15 years and non-smokers (n=10, mean age=37.6), Khat chewers for more than 15 years and smokers (n=13, mean age=36.8). ORIGINAL ARTICLE KHAT CHEWING AND SMOKING EFFECT ON ORAL MUCOSA:A CLINICAL STUDY Summary: Khat (Catha Edulis Forskal) is widely cultivated in Yemen and East of Africa. The habit of chewing tender leaves and twigs of khat is deep-rooted in Yemen. Our study investigates the chronic khat chewing and smoking effect on oral mucosa. The sample (n=79) consists of two main groups, khat chewers (n=54) and control groups (n=25). Khat chewers group is divided into 4 subgroups accord...

Crown lengthening procedure is aimed at exposure of sufficient crown structure accomplished by a gingivectomy, an apically positioned flap with osseous resection or the use of lasers. Our present clinical study is aimed to assess the clinical effectiveness of a diode laser for functional crown lengthening procedure and to compare it with the conventional procedure using the scalpel. Fourteen patients including males and females, aged 20- 40 years were recruited and divided into two groups to undergo crown lengthening either with the scalpel or the laser. The data obtained was analyzed for intergroup comparison with an Unpaired t-test and intragroup comparison was determined by ANOVA.Analysis of the intergroup results for pain showcased that there was a significant difference (P<0.002) in VAS scores of pain on the 3rd day as well as on the 7th day (P<0.044), with patients in the laser group displaying significantly lower VAS scores compared to the scalpel group, but when both the groups were compared on the 10th day, there was no significance (P<0.14).Intergroup comparison of the mean VAS scores for discomfort observed on the 3rd, 7th and the 10th day of the study suggested that there was a significant difference of the VAS scores of discomfort on the 3rd and the7thdays, with the patients in the laser group displaying significantly lower VAS scores for discomfort compared with the scalpel.Observations from the study emphasize that laser can be a safe and effective alternative to traditional crown lengthening performed with the scalpel.