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Background and Objective: Permanent first molars are susceptible to caries due to their particular anatomical form, early development and lack of knowledge of parents about their permanence. This study was conducted to determine the index of first permanent dental careis (DMF6) and some of its related factors in 12 year-old students.
Methods: This descriptive-analytical study was carried out on 400 students (200 females and 200 males) using combined method (stratified and cluster sampling) from public and non-governmental schools in Gorgan, northern Iran during 2015-16. First permanent molar examination was carried out. The parents' education level, frequency of toothbrushing and daily consumption of sugar-containing snack foods was recorded in a questionnaire. Each decayed, missing and filled first permanent molar tooth was given number one. These numbers were combined to compute the DMF6 index for each individual.
Results: The DMF6 index was zero in 19.5% and the DMF6 index was determined to be between
1 and 4 in 80.5% of the children. The mean DMF6 index was 2.23±0.07 and significantly higher in girls (2.39±0.10) than in boys (2.07±0.11) (P<0.05). The DMF6 index decreased with increasing parental education and the frequency of brushing and reducing consumption of sugary meals.
Conclusion: Dental caries prevalence among 12-years-old students in north of Iran is higher (2.23) than global standard until 2020 (lower than 1). Gender of child, parent’s education, frequency of toothbrushing and consumption of sugar-containing snack foods plays an important role in the rate of dental caries.

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Background and Objective: Oral and dental health are crucial for nutrition intake, speech, and facial aesthetics. They also significantly influence individuals' physical, social, and psychological activities. This study aimed to determine the relationship between the Dental Caries Index (DMFT) and oral health-related quality of life.
Methods: This descriptive-analytical study was conducted on 61 patients (29 men and 32 women) aged 20-50 years who visited the Gorgan Dental School Clinic, Iran during 2019. The DMFT index, encompassing Decay (D), Missing (M), and Filled (F) teeth, was calculated. Quality of life was assessed using the 36-item DIDL (Dental Impact on Daily Living) questionnaire, which covers five domains: dental appearance and aesthetics, oral comfort, overall oral and dental function, eating limitations, and dental and jaw pain. Scores were categorized into three groups: dissatisfied (below 0), moderately satisfied (0 to 7), and satisfied (above 7).
Results: The mean score for oral health-related quality of life was 5.14±0.229, indicating a relative level of satisfaction. Pearson's correlation coefficient between DMFT and oral health-related quality of life was -0.358, suggesting a significant inverse relationship between DMFT and quality of life (P<0.05). The mean DMFT score ranged from 0 to 28, with a mean of 9.36, and the most frequent scores were 7, 11, and 13, each accounting for 11.5% of the sample. The mean decay (D) score was 3.44, the mean missing (M) score was 1.98, and the mean filled (F) score was 3.93, with ranges of 0-12, 0-19, and 0-13, respectively.
Conclusion: The results of this study indicate an inverse impact of the Dental Caries Index on patients' quality of life. Oral health-related quality of life is a multifaceted construct that affects various aspects such as appearance, oral comfort, and eating limitations, which are critical components of overall quality of life and satisfaction.