Chronology of the First Deciduous Tooth Eruption in Brazilian Children with Microcephaly Associated with Zika Virus: A Longitudinal Study

Objective: To analyze the chronology of first deciduous tooth eruption in children with microcephaly associated with presumed or confirmed Zika virus. Material and Methods: A longitudinal study was developed with 74 children of both sexes. Data on prematurity, gestational age (in weeks), anthropometric characteristics at birth [length (cm), weight (g) and cephalic perimeter (cm)] and dental eruption (chronological age and corrected age for prematurity in months) were collected and presented through descriptive statistics. Data was analyzed using the Statistical Package for Social Sciences. Results: The majority of children were female (54.1%) and 14.9% were born premature. The mean gestational age was 38.2 (± 1.9) weeks, while length, weight and cephalic perimeter at birth were 45.6 (± 3.1) cm, 2750 (± 526.6) and 30 (± 2.3) cm, respectively. The eruption of the first tooth occurred on average at 12.3 (± 3.0) months of chronological age and at 11.1 (± 2.3) months of corrected age. The first erupted teeth were the lower deciduous central incisors (82.4%). The mean age for dental eruption in males was 12.5 months (± 3.0) and in females 12.0 months (± 3.1) among full-term children. For premature infants, the mean corrected age of dental eruption was 11.5 months (± 3.4) for boys and 11 months (± 1.7) for girls. Conclusion: In this group of children with microcephaly, the first tooth to erupt was the lower central incisor around the first year of life. Girls had lower average eruption time when compared to boys in both chronological age and age corrected for prematurity.

Impact of Saliva and Intraoral Appliance on Erosion Lesions Rehardening Ability - A Pilot Study

Objective: To evaluate the ability of different periods of salivary exposure and two different removable appliances to rehardening initial erosive lesions. Material and Methods: This randomized, single blind in situ study was conducted with 2 crossover phases. The factors under study were: period of salivary exposure (15 minutes, 30 minutes, 1 hour and 2 hours) and type of oral appliance (maxillary or mandibular). Two hundred enamel blocks were selected by initial surface hardness (SHi). Enamel blocks were demineralized in vitro (0.05M citric acid; pH2.5 for 15 seconds), surface hardness (SHd) was remeasured and 160 blocks were selected and randomized among groups. Thus, there were 2 blocks per period of salivary exposure in each type of oral appliance for each one of the 10 volunteers. In each phase, one of the removable appliances was tested. The response variable was percentage of surface hardness recovery (%SHR=[(SHf-SHd)/SHi)]x100). Two-way ANOVA and Tukey's post hoc test were applied adopting 5% of significance. Results: No difference was found among oral appliances on enamel rehardening (p>0.01). Salivary exposure of 2 hours promoted similar enamel rehardening when compared to 1 hour (p>0.05), which showed similar rehardening to 30 min. All mentioned period of salivary exposure promoted superior rehardening than 15 min (p>0.01). Conclusion: The salivary time exposure between erosive attacks might be 2 hours to achieve a feasible maximum rehardening. In addition, both maxillary and the mandibular appliance have presented a similar rehardening ability.