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    The Effect of Sympathetic Neural Supply On The Eruption Rate Of Rats’ Mandibular Incisors
    Kassab , Ammar; Chediac, José; Saade, Nayef E.; Jabbur, Suhayl J.; MS; Department of Anatomy, Cell Biology and Physiological Sciences; Faculty of Medicine
    Background: Tooth eruption is defined as the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity. The control of eruption mechanism is multifactorial, where the nervous system plays important role in the control of different contributors to this process. Aims: (1) to investigate the effect of neurotomy on the eruption rate of rats’ incisors, (2) and to evaluate the role of the sympathetic nervous system, in particular, in the eruption rate, (3) to explore the differences in eruption rate between intact and shortened incisors without altering the neural supply. Material and methods: Forty nine (49) adult female Sprague-Dawley rats divided into seven groups; group 1: (n=8) had guanethidine treatment (30 mg/kg/day; for one week) to block the sympathetic transmission at effector level; group 2: (n=8) received hexamethonium treatment (10 mg/kg/day; for one week) to produce sympathetic block at ganglionic level; group 3: (n=7) subjected to chemical ablation of capsaicin sensitive primary afferents, and followed by daily treatment with guanethidine (30 mg/kg/day; for one week); group 4: (n=7) had the left inferior alveolar nerve (IAN) cut; group 5: (n=5) served as a sham for axotomy group; group 6: (n=7) had their left mandibular incisor cut out of occlusion by 2-3 mm; group 7: (n=7) served as a control group. Two landmarks were used to measure eruption rate: the first landmark was a groove placed on the distal aspect of the incisor, while the second landmark was a tattoo placed at the attached gingiva at the distal margin of the tooth. Measurements were registered every 48hrs for a period of 144hrs. Statistical analysis of results was performed (ANOVA) and the significance was tested by post hoc Bonferroni's multiple range test. Results: The temporal evolution of the eruption of intact incisors elicited an initial fast ascension, followed by a phase of deceleration and decline at the end of the observation period. The eruption was significantly reduced in rats treated with guanethidine in 1st time segment (0.87 ± 0.06 mm vs. 1.18±0.15 mm in control, P<0.05) and at total observation period (2.57 ± 0.06 mm vs. 3.00 ± 0.16 mm; P< 0.01). The rate of eruption was attenuated in hexamethonium treated rats but measurements were not statistically significant. IAN section significantly attenuated eruption rate in 2nd (0.44 ± 0.13 mm, p<0.001), 3rd (0.47 ± 0.11 mm, p<0.001), and total time segments (1.8 ± 0.15 mm, p<0.001). Guanethidine treatment in rats with ablated CSPA fibers reduced eruption rate during the first (0.79 ± 0.07 mm; p < 0.05), second (0.66± 0.7mm; P< 0.001), and total (2.24 ± 0.08 mm; p<0.001) time segments. The rate of eruption of shortened incisors significantly increased at the 1st (1.67±0.2 mm; p<0.01) and 2nd (1.66±0.2 mm, p<0.05) time segments then presented a compensatory deceleration until the tooth reached the incisal plane (0.37±0.17 mm, p<0.01). Conclusion: the nervous system plays a key role in the control of the eruption process of rats’ mandibular incisors. Sympathetic supply appears to constitute a major component in this control.
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    The Effect of Capsaicin Sensory Primary Afferents on the Eruption Rate Of Rats’ Mandibular Incisors
    El Hage, Marianne; Chediac, José; Saade, Nayef E.; Jabbur, Suhayl E.; MS; Department of Anatomy, Cell Biology and Physiological Sciences; Faculty of Medicine
    Background and Aims: Tooth eruption is defined as the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity. Several studies aimed to investigate the neural effect on the eruption mechanism. Most of reported results were descriptive based on clinical observations and were not supported by experimental evidence. The present study aims to investigate (1) the possible involvement of the sensory nervous system in the eruption rate of mandibular incisors in rats, and 2) the possible involvement of substance P in this process. Materials and methods: Rats (adult female Sprague-Dawley) were divided into 5 groups; group 1, (n=7) had no chemical or surgical intervention (control group); group 2, (n=7) was subjected to the exposure and sectioning of the inferior alveolar nerve (IAN); group 3, (n=6) was subjected to selective ablation of the sensory afferent fibers to the incisor by topical application of capsaicin on the left IAN; group 4, (n=5), was the sham capsaicin group, where the capsaicin solvent was applied to the left IAN; group 5, (n=7) consisted of rats subjected to systemic ablation of their capsaicin sensitive primary afferents (CSPA); group 6, (n=8) was subjected to daily treatment with substance P antagonist, Spantide II. The method adopted to measure tooth eruption was based on two fixed reference points; the first reference was localized, with a groove, at the junction of the buccal and distal surface of the tooth and the second was a tattoo mark on the gingiva at the tooth base. A digital caliper (accuracy 0.01mm) was used for measurements, which were performed every 48hr over a period of 144 hours. Each measurement was repeated three times on each rat. Rats were sacrificed under deep anesthesia and the brainstem of rats of three groups (Control, Spantide II, and systemic capsaicin ablation) were collected and processed for the determination of substance P by Immunohistochemistry (IHC). The result obtained for each time point was presented as the mean and standard error of the mean (SEM) of measurements made on all rats in the same experimental group. Statistics were made using GraphPad Instat 3, and the significance of variations were calculated. Results: A general trend of reduction in the rate of eruption was observed in all groups. Significant reduction was observed in group 2 during the second (48-96hrs) and the third (96-144hrs) time segments, (0.44 ± 0.13mm) and (0.47 ± 0.11mm), respectively compared to control (0.79 ± 0.15mm) and (1.02 ± 0.14mm). Same pattern of attenuation was noticed in group 3 (0.41 ± 0.13mm, p < 0.01) as compared to the control (1.08 ± 0.09mm), as well as in group 6 (0.73±0.08mm, p < 0.05) compared to control (1.08±0.09 mm) at time point 48-96 hrs group 5 showed a significant attenuation of the eruption rate of the mandibular incisors at the initial time segment (0.64 ± 0.04 mm, p < 0.001) as compared to the control group (1.18±0.15 mm). IHC results showed a marked attenuation of substance P immunoreactivity in group 6 and a complete absence of immunoresctivity in G6 as compared to control. Conclusion: Capsaicin sensitive primary afferents play a major role in the control of the eruption process; however, their absence does not produce a permanent impairment.
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    Modulation of Cytokines in TNBS Induced Colitis Treated with Estrogen
    Jambart, Stephanie; Jurjus, Abdo R.; Barada, Kassem; Eid, Assaad; MS; Department of Anatomy, Cell Biology, and Physiological Sciences; Faculty of Medicine
    Background: Epidemiological studies showed that pregnant women and women under birth-control pills experienced less inflammation than other women. Even if estrogens were thought to have more pro- than anti-inflammatory-like reaction (because of their inflammatory-like reaction on the ovarian follicle maturation) there are now numerous experimental models where the lack of estrogens facilitates the onset of inflammation Objectives: This study investigated the anti-inflammatory effect of estrogen in TNBS induced colitis models, focusing specifically on the morphological changes, the activity of mast cells and the expression of cytokines (Interleukin 6 (IL-6), Tumor Necrosis Factor-α (TNF-α)), extra cellular matrix (fibronectin and collagen IV) as well as reactive oxidative species (ROS). Materials and Methods: 120 adult male SpragueDawley rats (n=120), weighing 250 to 300g, were divided into 4 groups: Group I: induced with colitis, not receiving treatment, Group II induced with colitis and treated with estrogen (17β-estradiol), Group III receiving estrogen only, Group IV not provided with anything. In groups I and II colitis was induced according to previously established procedures: 2,4,6-Trinitrobenzenesulfonic acid solution (TNBS) (n=20 for each group) and Dextran Sulfate Sodium Salt (DSS) (n=20 for each group). Rats were observed daily where scores was given to signs and symptoms. Biopsies of the colon, jejunum, liver and kidney were extracted from the rats on days 7, 14, 28 and 56, where macroscopic, microscopic and molecular evaluations were performed. Results: The rats from Group II receiving estrogen treatment, expressed statistically reduced clinical scores by approximately 10%. The gross morphologic inflammation alterations showed statistically significant amelioration when the rats were treated with estrogen by about 20 %. Estrogen reduced significantly the expression of collagen IV and fibronectin protein expressions as well as IL-6, TNF-α, and fibronectin gene expression by 20 %. ROS expression tested with the dihydroethidine (DHE) staining was significantly decreased by 30 %. Conclusions: Estrogen in experimental colitis depicted an overall preventive and or protective role. Rats treated with estrogen showed less inflammation at all time points, less necrosis and less production of ROS compared to non-estrogen treated animals.
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    Malocclusion And Orthodontic Treatment Need In Elementary School Children In Beirut: Prevalence And Related Factors
    Hanna, Antoine; Chaaya, Monique; Jaffa, Miran; Ghafari, Joseph; Kanj, Mayada; MS; Department of Epidemiology and Population Health; Faculty of Health Sciences
    Introduction: Malocclusion, defined as any deviation from the norm of the arrangement of the teeth, can be caused by genetic and/or environmental factors. Occlusal indices are used to quantify the severity of the malocclusion and assess the treatment need in a given population. Lebanon lacks data on the severity of malocclusion and its associated factors. The objective of this study was to assess the prevalence and severity of the malocclusion and orthodontic treatment need comparing between public and private schools in a sample of 6-11 years Lebanese elementary school children in Beirut as well as the relationship between these components and socio demographic and selected behavioral background factors of both children and parents. Design: A comparative cross-sectional study of elementary school children aged 6-11 years, grades 2 to 5, in public and private schools in Beirut-Lebanon. Methods: The sample comprised 655 school children aged 6-11 years selected from 2 public schools (PB) and 5 private schools (PV) in Beirut. Dental screening was performed by a calibrated examiner to record information regarding occlusion, overjet (OJ), overbite (OB), posterior crossbite (PXB), midline diastema and crowding (II). Data on socio-demographic background, health status, oral hygiene habits and nutritional habits were collected via a questionnaire sent to the parents. The index for orthodontic treatment need was computed (IOTN). Multinomial, binomial and multiple linear regressions were performed to test the association of selected factors with occlusal indices. Results: Malocclusion was more severe in PB compared to PV with statistically significant difference regarding overjet (p=0.22), anterior crossbite (p=0.008) and occlusion (p=0.002) when stratified based on the overjet. After adjusting for appropriate variables, age was positively associated with OJ (RRR: 1.35; 95%CI: 1.06; 1.71 / β: 0.14; 95%CI: 0.046; 0.249), OB (RRR: 2.23; 95%CI: 1.03; 4.83) and PXB (OR: 1.29; 95% CI: 1.18; 1.39). Increased sucking habit duration was associated with a shallower OB (RRR: 0.98; 95%CI: 0.97; 0.99) and a PXB (OR: 1.01; 95%CI: 1.01; 1.18). Crowding is more prevalent among males (RRR: 1.69; 95% CI: 1.36; 2.1) and is associated with an increase in the DMFT (Decayed, Missing, and Filled Teeth) score (RRR: 1.04; 95%CI: 1.03; 1.06), which was evaluated in another part of this epidemiologic study. The IOTN (Index of Orthodontic Treatment Need) scores revealed that nearly one fourth of the children are in urgent need of treatment. Conclusion: Orthodontic treatment need evaluated in Lebanese children 6-11 years of age is 2.7 times higher than in comparative data in the USA (ages 8-11 years). Differences in population age limit comparisons with data from other countries, however, the findings suggest the need for education campaigns to parents in order to have their children screened early for orthodontic needs (age 7) along with the integration of orthodontic screening in schools on an annual basis with greater attention in public schools. Mouth breathing and sucking habits should be detected in a timely manner. Long term follow up is needed on the screened subjects to build up a cohort for subsequent assessment of oral health in general and malocclusion in particular. Such data should form the basis for third-party entities (government, NGO agencies, and insurance companies) to engage in the prevention or early treatment of occlusal problems.
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    Assessment Of Dental Decays And Oral Hygiene In Elementary School Children In Beirut: A Comparison Between Private And Public Schools
    Moukarzel, Celine; Jaffa, Miran; Chaaya, Monique; Ghafari, Joseph; Kanj, Mayada; MS; Department of Epidemiology and Population Health; Faculty of Health Sciences
    Objective: To assess the decays and oral hygiene status in a sample of 6-11 years elementary school children in Beirut in terms of prevalence and associated factors. Methods: A comparative cross-sectional study of elementary school children aged from 6-11 years old, grades 2 to 5, in public and private schools in Beirut-Lebanon. The units of observation were both the child and the parents. The final study sample included 655 children from 2 public and 5 private schools in Beirut. The data were collected from 2 main sources: a dental screening of the children where the DMFT (Decayed, Missing, Filled Teeth) and plaque indices were recorded and a questionnaire completed by the parents. This survey addressed 5 sections including socio-demographic background, health status, oral hygiene habits and nutritional habits, to assess potential risk factors that could be associated with oral health. Descriptive analysis, bivariate and multivariable analyses were conducted to detect differences between schools and to test for associations between risk factors and DMFT and plaque indices. Results: The mean DMFT was 7.50±3.98 in public school children compared to 3.50±3.41 in private school participants (p 0.0001). The mean plaque index was also higher in public schools, the difference being statistically significant with private schools (p 0.0001). Similarly, the educational level of the parents and the monthly family income were lower in public schools compared to private schools (p 0.0001). Feeding mode, maternal smoking during pregnancy were also found to be statistically significantly different between school groups. The frequency of teeth brushing was remarkably higher in private schools, whereas the frequency of sweets and soda consumptions scored higher in public schools. The bivariate analysis showed that children from low socio-economic and educational backgrounds have greater DMFT and plaque indices compared to those of higher socio-economic and educational backgrounds who had higher frequency of teeth brushing and lower frequency of soda and sweets. The multivariable analysis showed that the oral health perception, the feeding mode and the school type were associated with the DMFT index whereby a bad oral health perception is correlation with a higher DMFT and bottle-feeding with a lower DMFT compared to breast-feeding. The plaque index was found to be associated with the oral health perception, a higher index being linked with bad oral health perception compared to a good one. Conclusion: The DMFT score in Lebanon is high, particularly in public schools, when compared to Europe and the United States. The rather alarming number, urge early detection and early interventions to prevent further complications and their effect on oral health. Of recognized major impact would be the development of educational programs to increase awareness about oral health issues that are not followed by Lebanese children in mid-childhood, especially the disadvantaged ones and thus to decrease the prevalence of dental decays. Also, parents of limited means should be informed of the availability of clinics that provide low-cost services for dental health. Finally, more research is needed toencompass epidemiologic studies of a wider scope of children at various ages, and ultimately gauge potential implementation of third party assistance in treatment costs as part of an overhaul of public health policies regarding oral health.