Our results showed that women who used DMPA had more pocket probing depth, clinical attachment loss, bleeding on probing and periodontitis than their matched control, and the differences was significant. Our study confirms and expands the findings of previous studies, which suggest that DMPA use may influence periodontal health. In concordance with our results, in a cross-sectional study (national health and nutrition examination surveys) among US females (15 to 44 years of age), Taichman et al. reported that past users of DMPA were more likely to have periodontitis (12.0% vs. 8.0%), and a significant differences was reported regarding to pocket probing depth and bleeding on probing among current and past DMPA users as compared to never users (P < 0.001) (
13). Also, in a clinical study by Seck-Diallo et al. women using injectable progestin-only contraceptives demonstrated more periodontal pocket probing depth (3.01 ± 0.04 vs 1.12 ± 0.61, P < 0.0001) and clinical attachment loss (3.19 ± 0.08 vs 1.94 ± 0.11, P < 0.0001) than nonusers (
12). In the present study, the mean pocket probing depth was much higher as compared to the two above-mentioned studies, which may be attributed to the duration of DMPA use. However, as the above studies did not disclose the duration of DMPA use of their population, it is difficult to make comparison. In another study, Tilakaratne et al. showed a statistically significant increase in clinical attachment loss among DMPA users as compared to nonusers (P < 0.0001), which is in accordance with our findings (
15). However, this study is in accordance with our result, their study has low number of DMPA users and DMPA use was assessed in combination of oral contraceptives. In a prospective 6-month clinical study conducted by Kazerooni et al. women using the progestin implant contraceptive (levonorgestrel) exhibited a statistically significant increase in gingival pocket depths over the study period as compared to nonusers, except around the distal aspect of the premolars (P = 0.09) and the mesial aspect of the anterior teeth (P = 0.07). Also, in this study the gingival index in the case group was significantly increased for the molar and premolar teeth at 6 months (P = 0.03 and P = 0.04) compared to bassline (
14).
A suggested mechanism for DMPA’s effect on periodontal tissues is that progestins, in its active form, may stimulate the synthesis of prostaglandins, thereby contributing to increased vascular permeability within the chronically inflamed periodontium (
17). Other possibility is that progestins may promote tissue catabolism possibly resulting in increased periodontal attachment loss (
18). So that DMPA suppresses estradiol concentrations, and estrogen deprivation has been associated with teeth loss, alveolar bone loss and periodontal attachment loss, there is a possibility that DMPA could adversely affect the periodontal structure (
7).
Our study involved some limitations that should be considered. First, this study is cross-sectional in design and because DMPA use and periodontal status were measured at one point in time, it is impossible to know whether the use of DMPA causes adverse periodontal changes. Furthermore, unmeasured variables related to oral health or other non-contraceptive use in DMPA users may have influenced the results. Despite these limitations, in this study duration of DMPA use and age of initiation as well as injection time were assessed compared to previous studies. To fully understand the mechanism of DMPA effect on periodontal health, future studies are needed. Also, use of more longitudinal and RCT designs are suggested.