This study was nested within a wider research project following-up on pregnant women, however, it was fully independent in both the design and execution of the oral examination and other measurements. The study was approved by the Ethics Committee of the University of Granada (reference 72-2015) and conducted in accordance with the principles of the Declaration of Helsinki, updated in Fortaleza, Brazil, in 2003.
Sample and setting
Participants were recruited through the Gynecology and Obstetrics Service of the Virgen de las Nieves University Hospital Complex in Granada, Spain. This complex houses a medical center which was responsible for a total of 2,956 deliveries in 2019. Women were recruited during 2018-2019 and were followed-up from week 10-12 of gestation to weeks 30-32. Women were invited to participate in the present study during their first prenatal routine appointment. In order to be included in the present research, women had to be aged >16 years old, in the 10th, 11th or 12th week of gestation at study start, and sign an informed consent form. Women were excluded if they were unable to sign inform consent, possessed any disability that impeded study participation, were pregnant with twins, had less than six teeth or had been treated for periodontal disease in the last six months. Finally, 295 women met inclusion criteria for the present research.
Oral Health Related-Quality of Life Assessment
OHRQoL was assessed during the first and third trimesters of gestation (weeks 10-12 and 30-32) using the OHIP-14 questionnaire. This questionnaire is a subjective oral health measurement that has proven to be an accurate, valid and reliable clinical tool (Cronbanch a=0.88). The OHIP-14 consists of 14 items which pertain to the frequency of adverse impacts on patient’s oral status during the previous months. It is assessed on a 5-point Likert scale (0 = never, 1 = hardly ever, 2 = occasionally, 3 = fairly often and 4 = very often) with potential final scores ranging from 0 to 56 and higher scores indicating poorer oral health. This tool was developed based on the conceptual model defined by Locker and focuses on seven domains: functional limitations, physical pain, psychological discomfort, physical disability, psychological disability, social disability and handicaps. These items represent a hierarchy of factors which have the potential to increasingly and negatively impact aspects of everyday life.
Oral Examination and Data Collection
Two trained dentists with experience in OHIP-14 assessment and periodontal disease examination (>80% inter-rater reliability for clinical attachment level, plaque index and OHIP assessment) performed all clinical measures at both follow-up timepoints. Oral examination was performed at the obstetrics and gynecology service office, under artificial light, using disposable dental mirrors and a “University of North Caroline” periodontal probe. Examinations followed WHO guidelines. Data on self-reported oral hygiene habits (tooth brushing, and use of mouthwash and floss), routine dental examinations and history of caries (DMFT index) were collected. In order to diagnose active non-plaque-induced gingivitis, “bleeding on probing (BOP)” (absence or presence of bleeding after probing to assess gingival inflammation) was assessed and oral hygiene was measured according to the Sillness and Löe plaque index. Finally, clinical attachment loss and periodontal pocket depth was measured for each tooth, except for the third molar, in order to evaluate periodontitis. Cases of periodontitis were defined in line with Tonetti MS et al. . This states that periodontitis is present when epithelial clinical attachment loss (vestibular-palatal) is > 3 mm and periodontal pocket depth is ≥3 mm in two or more teeth. Accordingly, gingivitis was defined as gingival inflammation with presence of bleeding when probing pockets with a depth of < 3mm.
Other socio-demographic variables such as age, level of education and employment status, body mass index (BMI), unhealthy habits (smoking), history of previous pregnancies and deliveries, obstetric history, and prescribed medication were collected at recruitment. During week 24 of gestation, participants were screened for gestational diabetes mellitus via the O’Sullivan test. Upon positive O’Sullivan’s test results (hyperglycemia in pregnancy), cases of gestational diabetes mellitus were diagnosed using the glucose challenge test.
During the first prenatal visit, all participants underwent an oral health examination, where they were also provided with oral health information in relation to oral diseases and conditions which could be experienced during pregnancy. The Spanish public health system closely follows-up pregnant women during their pregnancy through three routine prenatal visits to obstetrics and gynecology services (weeks 12, 24 and 32 of gestation). Women were assessed a second time during their last prenatal visit to the hospital. Here, their periodontal status was recorded, in addition to any changes in the number of teeth or the emergence of new caries. Women who underwent dental treatment or dental cleaning during the follow-up period were excluded from the study.
Qualitative variables were described as absolute frequencies and percentages. Numerical variables were described as mean and standard deviation or median and interquartile range whenever data were non-normally distributed. Normality of continuous variables was evaluated using the Kolmogorov-Smirnov test. Differences in characteristic of participants and oral health during the first and third trimesters of gestation were evaluated using bivariate analysis. The McNemar test was used to analyze qualitative variables. Student’s paired t-tests or the Wilcoxon signed-rank test were used for quantitative variables, depending on normality test outcomes.
OHIP was analyzed by calculating three summary variables, as suggested by Slade et al., :
- Prevalence: The percentage of respondents reporting one or more impacts “fairly often” or “very often.” This variable identifies those whose oral health impacts are chronic rather than transitory.
- Extent: The number of items reported “fairly often” or “very often.”
- Severity (overall score): The sum of the response codes for the 14 items. This considers impacts experienced at all frequency levels. Given the response codes, this score can range from 0 to 56, higher values indicate more frequent impacts.
No cut-off points for the OHIP-14 have been identified to identify patients at risk of poor oral health. Thus, to ease the interpretation of results, “severity” (defined as the sum of the scores obtained for the 14 items) was categorized using the median split, as described by Locker et al, for bivariate and multivariate analyses (median= 12.0, range: 10-18). “Extent” was categorized by a “0” if there were no negative answers, or “1” if there was at least one negative answer. Crude odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated to analyze the association between each variable and oral health status during the third trimester of gestation. Variables with a p value <0.10 following crude analyses were adjusted in the multivariate model. The selection criterion was based on a “backward stepwise selection” process, with variables producing a p value >0.10 being excluded at each step. We evaluated the contribution of each variable to the model using the likelihood-ratio test.