Prevalence of primate and interdental spaces for primary dentition in 3- to 6-year-old children in Taiwan.

BACKGROUND/PURPOSE: Spaced primary dentition plays a critical role in the eruption of permanent teeth and the establishment of ideal occlusion. A lack of these spaces in deciduous dentition may result in disproportionate jaw and tooth sizes. Additionally, spaced primary dentition is significantly affected by ethnic factors. However, few of these studies have been conducted in Asia. The purpose of this study was to investigate the prevalence of spaced primary dentition in Taiwan. METHODS: One hundred and forty-seven 3- to 6-year-old Taiwanese children (58 girls and 89 boys) were recruited for a cross-sectional study. Primate and interdental spaces were recorded by intraoral photos. The prevalence of spaced dentition was evaluated. The interpersonal agreement of spaced dentition between the upper and lower arches was also assessed. RESULTS: Most of the subjects had spaced primary dentition. The prevalence of primate space was 83.7% in the upper arch and 61.2% in the lower arch, whereas the prevalence of interdental space was 44.2% in the upper arch and 53.1% in the lower arch. The prevalence rates of interdental space and upper primate space were significantly higher in boys than in girls. Interdental spaces of the lower arch increased with age. CONCLUSION: Ethnic factors can affect the ratio of spaced dentition. Most of the 3- to 6-year-old Taiwanese children have spaced dentition. The boys have higher incidence of spaced dentition than the girls. Furthermore, primate space is more frequently found in the upper arch than in the lower arch, whereas interdental space is reversed.

Intermittent parathyroid hormone improve bone microarchitecture of the mandible and femoral head in ovariectomized rats.

BACKGROUND: Intermittent parathyroid hormone (PTH) can be used to treat osteoporosis of the spine and hip. However, whether it can be used to treat osteoporosis of the mandible is unclear. The purpose of this study was to explore the influence of applying intermittent PTH to ovariectomized rats on the trabecular bone microarchitecture of the mandible and femoral head. METHODS: Eighteen female rats were divided into three groups: the healthy group, ovariectomized (OVX) group, and OVX + PTH group. The OVX group and OVX + PTH group had an OVX at 8 weeks of age. The OVX + PTH group received intermittent PTH therapy for 12 weeks. The mandibles and femurs of all rats were removed at 20 weeks and were then scanned using microcomputed tomography (micro-CT). RESULTS: From the micro-CT analysis, the trabecular bone microarchitecture of the mandible and femoral head are offered as follows: (1) The bone volume fraction and trabecular thickness in the OVX group were lower than those in the healthy group. (2) The bone volume fraction and trabecular thickness in the OVX + PTH group approximated those in the healthy group. CONCLUSION: The conclusions of this study regarding the trabecular bone microarchitecture of the mandible and femoral head are offered as follows: (1) The BV/TV and TbTh in the OVX group were lower than those in the healthy group. (2) The BV/TV and TbTh in the OVX + PTH group approximated those in the healthy group, therefore, intermittent PTH displayed high efficacy for treating femoral or mandibular deterioration of bone microstructure resulting from loss of ovarian function. Osteoporosis of the femur or mandible in the rats was ameliorated by intermittent PTH therapy.

Bite-force difference among obese adolescents in central Taiwan.

BACKGROUND/PURPOSE: Maximal bite force of the jaw can cause thorough food chewing and result in good digestion. Bite force is related to the health of the masticatory muscles. Muscle force is frequently affected by obesity in adolescence, however, little is known about how obesity influences the maximum bite force and the difference between genders. METHODS: Five hundred and seventy-seven adolescent students (292 girls and 285 boys), aged 13-16 years, from central Taiwan were recruited for a cross-sectional study in 2009. The maximum bite force, hand strength, triceps skin-fold fat thickness, serum level of testosterone, and body mass index (BMI) were measured. Dental health was evaluated based on malocclusion and dental caries. RESULTS: Bite force in girls was highest in the obese group (32.49 ± 19.13 kg, mean ± standard deviation), whereas in boys it was higher in the overweight group (41.89 ± 19.3 kg) than in the obese group (33.21 ± 17.12 kg). The prevalence of obesity was twofold higher in boys (14.39%) than in girls (7.88%). The mean serum level of testosterone increased with BMI in girls (p = 0.0172), whereas it decreased with BMI in boys (p = 0.0014). The relationships of serum testosterone level and bite force with BMI were similar in the two gender groups. CONCLUSION: The maximum bite force decreased in obese boys but increased in obese girls, which may be due to the sensitivity to testosterone being modulated by the fat level.

Microcomputed tomography analysis of particular autogenous bone graft in sinus augmentation at 5 months: differences on bone mineral density and 3D trabecular structure.

OBJECTIVES: This study investigated the effects of gender on the three-dimensional (3D) bone mineral density (BMD) and micromorphology of the trabeculae of matured autogenous bone grafts after sinus floor augmentation, and compared them to those of adjacent native bone. MATERIALS AND METHODS: Ten bone biopsy samples were removed from the implant placement areas of patients who had received second-stage sinus floor augmentation, and analyzed by microcomputed tomography. BMD phantoms with two calcium hydroxyapatite densities (0.25 and 0.75 g/cm(3)) were used to determine the BMD of the grafted and native bone samples. The 3D structural parameters of the trabeculae, including percentage of bone volume (bone volume/tissue volume, BV/TV), trabecular thickness (Tb.Th), trabecular number, trabecular separation, trabecular pattern factor (Tb.Pf), and structure model index, were analyzed between males and females and between grafted bone and native bone. RESULTS: No significant gender-specific differences in BMD and 3D trabecular structure of either native or grafted bone were found (P > 0.05). Compared to the adjacent native bone, the autogenous grafted bone exhibited lower BV/TV and Tb.Th as well as a higher Tb.Pf (P < 0.05). Additionally, there was a weak positive correlation between the Tb.Th values of grafted and native bone (R (2) = 0.58). CONCLUSIONS: In the maxillary sinus, autogenous grafted bone exhibited lower BV/TV, Tb.Th, and trabecular connectivity than the adjacent native bone. No significant gender-specific differences were found for either the BMD or 3D trabecular structure of grafted bone. CLINICAL RELEVANCE: After bone remodeling, autogenous grafted bone revealed different 3D trabecular structure as compared to native bone.

Three-dimensional bone structure and bone mineral density evaluations of autogenous bone graft after sinus augmentation: a microcomputed tomography analysis.

OBJECTIVE: The purpose of this study was to determine the relationships and differences in three-dimensional (3D) bone mineral density (BMD) and microtrabecular structures between autogenous bone grafts and their adjacent native bone after a healing period following maxillary sinus augmentation. MATERIALS AND METHODS: Nine rod-shaped human bone biopsy samples were taken from patients receiving two-stage sinus augmentation therapy in implantation areas and analyzed using microcomputed tomography (micro-CT). Before micro-CT scanning, two BMD phantoms were placed near to the bone biopsy samples for executing BMD calculations of the grafted and native bone samples. In addition, 3D structural parameters of the trabeculae were analyzed for both the grafted and native bone, including percentage of bone volume [bone volume (BV)/tissue volume (TV)], bone-specific surface [bone surface (BS)/BV], trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), trabecular pattern factor (Tb.Pf), and structure model index (SMI). RESULTS: No significant correlations with regard to BMD and trabecular-structure parameters were found between native bone and grafted bone; however, BS/BV and Tb.Pf were higher and Tb.Th and Tb.Sp were 37.35% and 12.74% lower in grafted bone than in native bone. For grafted bone, there were significant correlations (P < 0.05) between BMD and BV/TV, and Tb.N. CONCLUSIONS: When using autogenous bone as a graft material, BMD and micromorphological conditions of grafted bone were not influenced by the condition of the native bone in the maxilla. Differences were found in surface complexity, trabecular thickness, trabecular separation, and the connectivity of trabeculae between grafted and native bone. The BMD in grafted bone was affected by the quantity of the trabeculae.

Effects of orthodontic tooth movement on alveolar bone density.

The object of this study was to evaluate the relationship between changes in the alveolar bone density around the teeth and the direction of tooth movement by using cone-beam computed tomography (CBCT). CBCT was used to measure the bone densities around six maxilla anterior teeth before and after 7 months of orthodontic treatment in eight patients. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Three-dimensional computer models of the maxilla before and after orthodontic treatment were created to detect the direction of tooth movement. The percentage for all 144 samples [8 (patients) × 6 (teeth) × 3 (levels)] in which the side (palatal, distal, mesial, or buccal sides) of maximum bone density reduction (before and after orthodontic treatment) coincided with the direction of tooth movement was calculated; this was referred to as the "coincidence percentage". The bone density around the teeth reduced by 24.3 ± 9.5%. The average coincidence percentage for the eight patients was 59.0%. The coincidence percentages for the eight patients were 62.5%, 62.5%, and 52.1% at the cervical, intermediate, and apical levels, respectively. The obtained results demonstrate that the direction of tooth movement is associated with the side of maximum bone density reduction, and that CBCT is a useful approach for evaluating bone density changes around teeth induced by orthodontic treatment.

Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study.

OBJECTIVES: The aim of this study was to evaluate the effects of cortical bone thickness and trabecular bone elastic modulus on the strain in the bone surrounding an immediately loaded implant. We also examined the correlations between bone structure and the following indices of primary implant stability: insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ). MATERIAL AND METHODS: The ITV, PTV, and ISQ were measured in 24 artificial jaw bone models representing cortical bone with four thicknesses (0, 1, 2, and 3 mm) and trabecular bone with four elastic moduli (137, 47.5, 23, and 12.4 MPa). Two loading conditions were applied (force of 130 N applied vertically and at 45° laterally), and the strains in the crestal region were measured by rosette strain gauges with a data acquisition system. RESULTS: When the cortical bone thickness and the elastic modulus of trabecular bone decreased, the bone strains increased by 10.3-52.1% and 39-73.1%, respectively, for vertical loading and by 35-62% and 42.4-56.2% for lateral loading. The cortical bone thickness has a stronger correlation (R(2) =0.95-0.71) with ITV, PTV, and ISQ than the elastic modulus of trabecular bone (R(2) =0.89-0.59). CONCLUSIONS: The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the elastic modulus of trabecular bone; however, these parameters are not totally linearly correlated with ITV, PTV, and ISQ. The placement of an immediately loaded implant in cases with thin cortical bone and/or weak trabecular bone can induce extreme bone strains and may increase the risk of implant failure.

Bone density changes around teeth during orthodontic treatment.

The objective of this study was to evaluate bone density changes around the teeth during orthodontic treatment by using cone beam computed tomography (CBCT). CBCT was used to measure the bone densities around six teeth (both maxilla central incisors, lateral incisors, and canines) before and after 7 months of orthodontic treatment in eight patients. In addition, each root was divided into three portions (cervical, intermediate, and apical) to determine whether the bone density change varied with tooth level. The mean reduction in bone density around the measured teeth was 24% after orthodontic treatment. The bone density reduction around teeth was largest for the upper-right and upper-left central incisor (29% and 26%, respectively) and ranged from 20% to 23% for the other four teeth. The mean bone density reduction did not differ significantly between the cervical, portion, and apical portions of the teeth (26%, 22%, and 24%, respectively). CBCT is useful for evaluating bone density changes around teeth during orthodontic treatment. The bone density around the teeth reduced significantly after the application of orthodontic forces for 7 months.

Treatment success with titratable thermoplastic mandibular advancement devices for obstructive sleep apnea: A comparison of patient characteristics.

A titratable thermoplastic mandibular advancement device (MAD) is clearly an effective treatment option in some patients with obstructive sleep apnea (OSA). Determining which patients may be more likely to respond to treatment with thermoplastic MADs and to adhere to treatment would be of obvious clinical relevance. This was an experimental descriptive study (N = 60). Patients with OSA were instructed to wear a titratable thermoplastic MAD for 3 months. Treatment success was defined as a ≥50% reduction from baseline in the apnea-hypopnea index (AHI) or AHI <10 when wearing MAD. Adherence was defined as MAD use ≥5 nights/week. Treatment was successful in 66.7% of patients and 60.0% were adherent. All polysomnographic parameters and visual analogue scale scores (sleep quality, snoring, waking refreshed) were significantly improved after treatment. The patients in whom treatment failed had significantly higher neck circumferences (39.3 cm vs. 37.5 cm, p = 0.014), higher baseline AHI values (26.6 vs. 18.0, p = 0.016), and smaller AHI reduction (-31.8 vs -53.1, p < 0.001) than those in the group in whom treatment succeeded. There were no significant differences in polysomnographic, cephalometric, or visual analogue scale measures between patients for whom treatment was and was not successful, regardless of baseline values or the change rates after the MAD was placed. Titratable thermoplastic MADs can improve indicators of sleep quality, even in patients in whom treatment is considered to have failed.

Does Orthodontic Treatment Affect the Alveolar Bone Density?

Few studies involving human participants have been conducted to investigate the effect of orthodontic treatment on alveolar bone density around the teeth. Our previous study revealed that patients who received 6 months of active orthodontic treatment exhibited an ∼24% decrease in alveolar bone density around the teeth. However, after an extensive retention period following orthodontic treatment, whether the bone density around the teeth can recover to its original state from before the treatment remains unclear, thus warranting further investigation.The purpose of this study was to assess the bone density changes around the teeth before, during, and after orthodontic treatment.Dental cone-beam computed tomography (CBCT) was used to measure the changes in bone density around 6 teeth in the anterior maxilla (maxilla central incisors, lateral incisors, and canines) of 8 patients before and after orthodontic treatment. Each patient underwent 3 dental CBCT scans: before treatment (T0); at the end of 7 months of active orthodontic treatment (T1); after several months (20-22 months) of retention (T2). The Friedman test was applied to evaluate the changes in the alveolar bone density around the teeth according to the 3 dental CBCT scans.From T0 to T1, a significant reduction in bone density was observed around the teeth (23.36 ±â€Š10.33%); by contrast, a significant increase was observed from T1 to T2 (31.81 ±â€Š23.80%). From the perspective of the overall orthodontic treatment, comparing the T0 and T2 scans revealed that the bone density around the teeth was relatively constant (a reduction of only 0.75 ±â€Š19.85%). The results of the statistical test also confirmed that the difference in bone density between T0 and T2 was nonsignificant.During orthodontic tooth movement, the alveolar bone density around the teeth was reduced. However, after a period of bone recovery, the reduced bone density recovered to its previous state from before the orthodontic treatment. However, the bone density around ∼10% of the teeth in this region could not recover to 80% of its state from before the orthodontic treatment.

The effects of cortical bone thickness and trabecular bone strength on noninvasive measures of the implant primary stability using synthetic bone models.

PURPOSE: This study investigated how the primary stability of a dental implant as measured by the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) is affected by varying thicknesses of cortical bone and strengths of trabecular bone using synthetic bone models. MATERIALS AND METHODS: Four synthetic cortical shells (with thicknesses of 0, 1, 2, and 3 mm) were attached to four cellular rigid polyurethane foams (with elastic moduli of 137, 47.5, 23, and 12.4 MPa) and one open-cell rigid polyurethane foam which mimic the osteoporotic bone (with an elastic modulus 6.5 MPa), to represent the jawbones with various cortical bone thicknesses and strengths of trabecular bone. A total of 60 bone specimens accompanied with implants was examined by a torque meter, Osstell resonance frequency analyzer, and Periotest electronic device. All data were statistically analyzed by two-way analysis of variance. In addition, second-order nonlinear regression was utilized to assess the correlations of the primary implant stability with the four cortex thicknesses and five strengths of trabecular bone. RESULTS: ITV, ISQ, and PTV differed significantly (p < .05) and were strongly correlated with the thickness of cortical bone (R(2) > 0.9) and the elastic modulus of trabecular bone (R(2) = 0.74-0.99). CONCLUSIONS: The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the strength of trabecular bone; however, these factors are mostly nonlinearly correlated with ITV, PTV, and ISQ. Using ITV and PTV seems more suitable for identifying the primary implant stability in osteoporotic bone with a thin cortex.

Relation between initial implant stability quotient and bone-implant contact percentage: an in vitro model study.

OBJECTIVE: This study evaluated the correlation between the initial stability of a dental implant, quantified as the implant stability quotient (ISQ), and the bone-implant contact percentage ( BIC%). STUDY DESIGN: Dental implants were inserted into specimens comprising an artificial cortical shell representing cortical bone and foam bone representing cancellous bone with 4 elastic moduli. Each specimen with an implant was subjected to microcomputed tomography (micro-CT) scanning, from which the 2D and 3D BIC% values were calculated. The values of the Spearman correlation coefficient (r) were calculated between the ISQ and the 2D and 3D BIC% values. RESULTS: Increasing the elasticity of the specimen enhanced the ISQ. There was statistically significant correlation between the ISQ and 3D BIC% values (r = 0.85, P < .0001). However, the correlation between ISQ and 2D BIC% values was not statistically significance (r = 0.42, P = .062). CONCLUSIONS: The initial implant stability was strongly positively correlated with the 3D BIC%.

[Evaluation of adrenocortical function in children with severe and critical enterovirus 71 infection].

OBJECTIVE: To evaluate the adrenocortical function in children with severe and critical enterovirus 71 infection by using a high-dose (250 µg) adrenocorticotropic hormone (ACTH) stimulation test. And to at provide experimental basis for glucocorticoid in the treatment of hand-foot-and-mouth disease (HFMD). METHOD: This was a prospective multi-center study which was carried out in PICUs of Beijing Children's Hospital, Zhengzhou Children's Hospital, Kaifeng Children's Hospital and Linyi People's Hospital in Shandong province. Children with severe and critical hand-foot-mouth disease admitted to PICUs of the four hospitals from June 2009 to April 2010 were enrolled in this study, and EV71 virus nucleic acid test and high-dose (250 µg) ACTH stimulation started at the same time. EV71 virus nucleic acid positive 51 cases were eventually enrolled in the study. Cortisol test was performed at baseline (T0) and after high-dose (250 µg) ACTH stimulation at 30 minutes (T30), 60 minutes (T60) in the first 6 hours after admission, but before glucocorticoid was given. The adrenocortical function was evaluated according to ΔTmax [ΔTmax=(T30, T60 maximum)-T0]. Diagnostic criteria of adrenal insufficiency (AI) is increment (ΔTmax)≤9 µg/dl. RESULT: The incidence of AI in 51 cases was 52.94% (27/51). The incidence of AI in severe group was 44.74% (17/38), which was significantly higher in critical group 76.92% (10/13), P<0.05. Of the cases with a pediatric critical illness score (PCIS)≤70, 81.82% (9/11) had adrenal insufficiency, and it was 28.57% (4/14) when PCIS≥90. The incidence of AI was 75% (6/8) and 48.84% (21/43) in death and survivor group respectively, but there were no significant difference between the two groups (P>0.05). Baseline (T0) cortisol in death group was higher than survivor group (P<0.05). CONCLUSION: AI may occur in children with enterovirus 71 infection. The critical enterovirus 71 infection had a high incidence of AI. AI may affect the prognosis of patients with severe and critical enterovirus 71 infection. Exogenous glucocorticoids administration may be considered when AI is identified or highly suspected. The timing, dosage and regimen of glucocorticoid are still unclear. Further animal experiments and clinical trials are needed.