Meta-analysis and systematic review of the number of non-syndromic congenitally missing permanent teeth per affected individual and its influencing factors.

BACKGROUND AND PURPOSE: Dental aplasia (or hypodontia) is a frequent and challenging anomaly and thus of interest to many dental fields. Although the number of missing teeth (NMT) in each person is a major clinical determinant of treatment need, there is no meta-analysis on this subject. Therefore, we aimed to investigate the relevant literature, including epidemiological studies and research on dental/orthodontic patients. METHODS: Among 50 reports, the effects of ethnicities, regions, sample sizes/types, subjects' minimum ages, journals' scientific credit, publication year, and gender composition of samples on the number of missing permanent teeth (except the third molars) per person were statistically analysed (α = 0.05, 0.025, 0.01). LIMITATIONS: The inclusion of small studies and second-hand information might reduce the reliability. Nevertheless, these strategies increased the meta-sample size and favoured the generalisability. Moreover, data weighting was carried out to account for the effect of study sizes/precisions. RESULTS: The NMT per affected person was 1.675 [95% confidence interval (CI) = 1.621-1.728], 1.987 (95% CI = 1.949-2.024), and 1.893 (95% CI = 1.864-1.923), in randomly selected subjects, dental/orthodontic patients, and both groups combined, respectively. The effects of ethnicities (P > 0.9), continents (P > 0.3), and time (adjusting for the population type, P = 0.7) were not significant. Dental/orthodontic patients exhibited a significantly greater NMT compared to randomly selected subjects (P < 0.012). Larger samples (P = 0.000) and enrolling younger individuals (P = 0.000) might inflate the observed NMT per person. CONCLUSIONS: Time, ethnic backgrounds, and continents seem unlikely influencing factors. Subjects younger than 13 years should be excluded. Larger samples should be investigated by more observers.

Meta-analysis of congenitally missing teeth in the permanent dentition: Prevalence, variations across ethnicities, regions and time.

BACKGROUND: Congenitally missing teeth (CMT) are of concern to many fields of dentistry. Only a few reviews have been published in this regard. AIM: The aim was to analyze the literature on CMT in the permanent dentition, excluding the third molars, and to identify potential links with ethnicity, geographical regions, and time. METHODS: A total of 118 reports on CMT were collected by two authors by interrogating databases. Sample homogeneity, publication bias, publication year (in Caucasian and Mongoloid samples, and in general), ethnicities, and geography of CMT prevalence were statistically analyzed using a Q-test, Egger regression, linear regression, a Spearman coefficient, Kruskal-Wallis, a Dunn post-hoc (α = 0.05), and a Mann-Whitney U test (α = 0.0125, α = 0.0071). RESULTS: The mean CMT prevalence was 6.53% ± 3.33%. There were significant geographic differences in CMT rates (P = 0.0001, Kruskal-Wallis) and between ethnicities (P = 0.0002, Kruskal-Wallis). According to the Mann-Whitney U test (α = 0.0071), eastern Asians (P = 0.0008) and Europeans (marginally significant, P = 0.0128) showed an elevated prevalence, while Western Asians (P = 0.0001) and Americans (marginally significant, P = 0.0292) had lower prevalence rates. Compared with other ethnicities, Mongoloids showed higher prevalence (P = 0.0009) while Asian Caucasians showed lower rates (P = 0.0005, Mann-Whitney U, α = 0.0125). The year of publication was not significantly correlated with any of the subsamples studied (P > 0.3, linear regression). CONCLUSIONS: Clinicians should be vigilant in the assessment of CMT in Mongoloids. No increase of this condition was detected during the last century.

Pain and discomfort perceived during the initial stage of active fixed orthodontic treatment.

BACKGROUND AND OBJECTIVES: As the most common complication of orthodontic treatment, pain can negatively impact quality of life and cause patients to discontinue treatment. However, few studies have evaluated pain during orthodontic treatment, with controversial findings. This study assessed the intensity and duration of pain and discomfort caused by active orthodontic treatment. METHODS: This descriptive cross-sectional study examined 67 patients (22 men, 45 females; age range: 18-32 years) undergoing fixed orthodontic treatment. Patients were interviewed after the active treatment stage to assess their perceived pain and discomfort at different sites during different activities by a visual analogue scale. Frequency and duration of pain in different areas were analyzed by the chi-squared and chi-squared goodness-of-fit tests (α = 0.05). RESULTS: Among the 67 patients, 65.7% experienced general dentogingival pain or discomfort and 34.3% had localized dentogingival pain or discomfort (p = 0.010, chi-squared goodness-of-fit test). Masticating soft foods reduced discomfort (p = 0.000, chi-squared) in the tongue, cheeks, and in or around the teeth and gingivae. Pain and discomfort were mostly moderate while masticating sticky, fibrous, and firm foods. Mild pains were mostly reported during tooth brushing and while consuming soft foods (p < 0.05, chi-squared). Pain and discomfort tended to last for more than 4 weeks, except in the tongue, where pain and discomfort lasted less than 4 weeks (p < 0.05, chi-squared goodness-of-fit test). CONCLUSIONS: Pain and discomfort occur for more than 4 weeks after beginning fixed orthodontic treatment. Changing diets to incorporate softer foods is recommended to alleviate pain.

A four-week solubility assessment of AH-26 and four new root canal sealers.

BACKGROUND: The strong link between sealer solubility and periapical reinfection indicates that water solubility of new sealers should be studied. This study aimed to assess the water solubility of five root canal sealers (AH-26, Topseal, 2-Seal, Acroseal, and Roeko Seal Automix [RSA]). MATERIALS AND METHODS: In this in vitro experimental study, 30 specimens were fabricated from each of the abovementioned sealants. Then they were weighed and randomly divided into three subgroups of 10 each (A, B, and C). They were set at 37°C and 100% RH, in accordance with ANSI/ADA 57 and ISO 6876-2001 requirements. Afterward, the specimens in subgroups A were incubated at 37°C and 100% RH for 24 hours, while the specimens in the subgroups B and C were incubated in the same conditions for 7 days and 28 days, respectively. After incubation, the specimens were dried with blotting paper and were incubated for 24 hours at 37°C and 0% RH. Then they were weighed. The percentage of weight loss was regarded as water solubility. RESULTS: The mean solubility of the sealers AH-26, Acroseal, Topseal, 2-Seal, and RSA were 0.28%, 0.36%, 0.07%, 0.037%, and 0.141% after 24 hours, respectively. After 28 days, their solubility were 1.75%, 0.746%, 0.082%, 0.04%, and 0.517%, respectively. Only the solubility of the sealers 2-Seal and Topseal were not statistically different (P>0.3 [Tukey's]). Again only the solubility of 2-Seal and Topseal did not significantly increase between the 7(th) day and the 28(th) day of incubation (P>0.6 [paired-samples t]). CONCLUSION: All tested materials met the standards (maximum weight loss of 3% within 24 hours). However, the results of 2-Seal followed by Topseal were the most favorable ones.

Association between orthodontic treatment need and masticatory performance.

AIM: This retrospective cohort study assessed the differences between the masticatory performance of individuals with and without orthodontic treatment need. METHODS: Masticatory performances of 120 participants with equal numbers of males and females (n = 60 each) with and without treatment need (n = 60 each, determined using the index of the complexity, outcome, and need [ICON]) matched by age and sex were assessed. Participants chewed on test foods at sequences of 20, 30, 40, 40, 30, and 20 masticatory cycles. After sieving the chewed particles, the masticatory parameters (median particle size [MPS], masticatory frequency [MF], and broadness of particle distribution [BPD]) were calculated. The associations between treatment need and the MPS with age, weight, and stature, as well as the relationship between sex and MPS and MF, were assessed. RESULTS: According to the independent samples t test, MPS of subjects with and without treatment need differed significantly (P < .05) while MF did not. The differences between BPD values reached the level of significance only after 40 cycles of mastication (P < .05). Females showed significantly greater MPS values. Only at the 40-cycle sequence did females in need of treatment chew significantly slower. According to the repeated-measures ANOVA, no significant differences existed (P > .05) between each of the MPS, MF, and BPD values measured at different sequences. No significant correlations were found between MPS and age, sex, or stature (P > .05 [Spearman correlation coefficient]). CONCLUSION: The masticatory performance of individuals with and without treatment need differed for MPS and BPD (at the 40-cycle sequence). Age, weight, and stature did not affect the treatment need and MPS. Females showed poorer results regarding MPS--only at the 40-cycle sequence did females with malocclusion chew significantly slower.

The effect of acidulated phosphate fluoride incorporated phosphoric acid etchant on shear bond strength of orthodontic brackets.

BACKGROUND: The aim of this study was to evaluate the effect of adding acidulated phosphate fluoride (APF) to phosphoric acid etchant on shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets bonded to etched teeth. METHODS: In this in vitro experimental study, 40 human premolars were etched with 37% phosphoric acid solution (Dentsply) blended with 0, 25%, 50%, and 75% fractions of 1.23% APF (Dentsply). The brackets (Mini Dyna Lock, 3M) were bonded (Transbond XT, 3M) and were subjected to 96 hours of 37°C incubation and thermocycling procedures (2000 cycles, 5-55°C, dwell time = 30 s). Then, they were debonded at 1-mm crosshead speed to measure the SBS. The ARI was estimated at 10× magnification. The data were analyzed using the tests one-way analysis of variance (ANOVA), Tukey, chi-square, one-sample t-test, and Spearman correlation. RESULTS: The SBS of the groups control, 25%, 50%, and 75% APF were 11.90±2.72, 8.01±3.13, 5.40±2.51, and 3.27±2.01 MPa, respectively. Mean ARI scores of these groups were 2.4 (control), 4.3, 4.7, and 4.8, respectively. According to the Tukey's test, only the mean SBS of the second group (25%) was not different from the control group (P=0.091). CONCLUSION: Adding about 20-25% of 1.23% APF to the phosphoric acid etchant might considerably reduce the amount of residual adhesive, without compromising the SBS.