The main goal of periodontal treatment is the long-term maintenance of teeth. Periodic maintenance program is need to prevent periodontal disease and maintain healthy periodontium. Hirschfeld and Wasserman(1978) studied 600 treated periodontal patients. This study categorized periodontal patients using well-maintained, downhill, extreme downhill groups. The purpose of our study is to evaluate effect of periodontal treatment and analyse tooth loss after periodontal treatment using this classification. The study population of j9 patients had been treated and maintained for mean 5.8 years. All patients were on a periodic maintenance program at 2-, 3-, 4, or 6-month intends. The avenge age of the patients at the time of original therapy was 49.6 years. To analyse tooth loss, modified classification was used on the basis of response to therapy using by Hirschfeld and Wasserman in 1978. The results were as follows : 1. 59 treated patients were lost mean 1.42 teeth per patient for 5.8 years of maintenance period. 2. Maxillary first molars were most frequently lost but mandibular lateral incisors were lost no tooth during maintenance period. 3. Tooth mortality received surgical treatment had similar to received nonsurgical treatment. 4. Tooth loss was more frequent in maxillary teeth than mandibular teeth, and posterior teeth than anterior teeth, and more frequent tendency in male than female.