Short-term oral bisphosphonates do not affect implant survival. In recent years, oral and maxillofacial surgeons have recognized that patients who take intravenous bisphosphonates to reduce the bone pain and hypercalcemia of malignancy occasionally will develop necrotic bone lesions after undergoing oral surgical procedures. Today, millions of adults take oral bisphosphonates on a regular basis to limit the negative effects of osteopenia and osteoporosis. Many of these individuals require the placement of dental implants to restore edentulous areas of the mouth. However, surgeons are concerned that osteonecrosis could be a negative surgical side effect in these oral bisphosphonate users. A
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DOI: 10.2319/122106-52.1
Objective: To compare accuracy of linear measurements made on cone beam computed tomographic (CBCT) derived 3-dimensional (3D) surface rendered volumetric images to direct measurements made on human skulls.
Materials and Methods: Twenty orthodontic linear measurements between anatomical landmarks on 23 human skulls were measured by observers using a digital caliper. The skulls were imaged with CBCT and Dolphin 3D (version 2.3) software used to generate 3D volumetric reconstructions (3DCBCT). The linear measurements between landmarks were computed by a single observer three times and compared to anatomic dimensions using Student's t-test (P ≤ .05). The intraclass correlation coefficient (ICC) and absolute linear and percentage error were calculated.
Results: The ICC for 3DCBCT (0.975 ± 0.016) was significantly less than for skull (0.996 ± 0.007) measurements. Mean percentage measurement error for 3DCBCT (2.31% ± 2.11%) was significantly higher than replicate skull measurements (0.63% ± 0.51%). Statistical differences between 3DCBCT means and true dimensions were found for all of the midsagittal measurements except Na-A and six of the 12 bilateral measurements. The mean percentage difference between the mean skull and 3D-based linear measurements was −1.13% (SD ± 1.47%). Ninety percent of mean differences were less than 2 mm, and 95% confidence intervals were all less than 2 mm except for Ba-ANS (3.32 mm) and Pog-Goleft (2.42 mm).
Conclusions: While many linear measurements between cephalometric landmarks on 3D volumetric surface renderings obtained using Dolphin 3D software generated from CBCT datasets may be statistically significantly different from anatomic dimensions, most can be considered to be sufficiently clinically accurate for craniofacial analyses.Abstract
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DOI: 10.2319/040207-166.1
Objective: To assess the plotting reproducibility of landmarks on 3-dimensional computed tomography (3D-CT) images through use of the 95% confidence ellipse in order to propose sufficiently stable coordinate systems for 3D-CT measurements.
Materials and Methods: Six dentists plotted 19 landmarks twice on 3D-CT images. Scatterplots and the 95% ellipses were produced 3-dimensionally, and the areas of the ellipses were calculated for evaluating the reproducibility of landmarks.
Results: The plotting reproducibility of each landmark showed characteristic features. Among five landmarks (the sella [S], nasion [N], basion [Ba], orbitale [Or], and true porion [Po]) that are frequently used as reference points on cephalograms, Ba showed the smallest areas for all three coordinate axes, indicating high reproducibility. The coronoid process (CP) and the tooth-related landmarks showed relatively high reproducibility.
Conclusion: Sufficiently stable coordinate axes could be proposed for different treatments and studies.Abstract
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DOI: 10.2319/051607-237.1
Objectives: To evaluate area- and gender-related differences in the soft tissue thickness of potential areas for installing miniscrews in the buccal-attached gingiva and the palatal masticatory mucosa.
Materials and Methods: The sample consisted of 61 Korean young adults. An ultrasonic gingival-thickness meter was used to measure the soft-tissue thickness in the buccal-attached gingiva just adjacent to the mucogingival junction of the upper and lower arches and 4 mm and 8 mm below the gingival crest in the palatal masticatory mucosa. Independent t-test, paired t-test, and one-way analysis of variance were used for statistical analysis.
Results: Buccal-attached gingiva thickness in the upper arch was significantly greater in men than in women, but buccal-attached gingiva thickness in the lower arch and palatal masticatory mucosa thickness 4 and 8 mm below the gingival crest did not show gender differences. Significantly thicker soft tissue occurred in the anterior areas in the upper arch and in the posterior areas in the lower arch. In the palatal masticatory mucosa, significantly thicker soft tissue was found 4 mm below the gingival crest in the anterior areas and 8 mm below the gingival crest in the posterior areas. The areas between the canines and the premolars showed higher values than other areas 4 mm below the gingival crest. However, the soft-tissue thickness 8 mm below the gingival crest showed a progressive increase from the anterior to the posterior areas.
Conclusion: Measurements of the soft-tissue thickness using an ultrasonic device could help practitioners select the proper orthodontic miniscrew in daily clinical practice.Abstract
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DOI: 10.2319/050407-217.1
Objective: To test the null hypothesis that rapid maxillary expansion (RME) with a rigid bonded appliance has no effect on conductive hearing loss (CHL) in growing children.
Materials and Methods: Fifteen growing subjects (mean age 13.43 ± 0.86 years) who had narrow maxillary arches and CHL participated in this study. Three pure-tone audiometric and tympanometric records were taken from each subject. The first records were taken before RME (T1), the second after maxillary expansion (T2) (mean = 0.83 months), and the third after retention (mean = 6 months) and fixed appliance treatment (approximately 2 years) periods (T3). The data were analyzed by means of analysis of variance (ANOVA) and least significant difference (LSD) tests.
Results: Hearing levels of the patients were improved and air-bone gaps decreased at a statistically significant level (P < .001) during active expansion (T2–T1) and the retention and fixed appliance treatment (T2–T3) periods. Middle ear volume increased in all observation periods. However, a statistically significant increase was observed only in the T2–T3 period. No significant change was observed in the static compliance value.
Conclusions: The hypothesis is rejected. RME treatment has a positive and statistically significant effect on both improvements in hearing and normal function of the eustachian tube in patients having transverse maxillary deficiency and CHL.Abstract
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DOI: 10.2319/021907-80.1
Objective: To examine inconsistencies in the differential diagnosis of open bite.
Materials and Methods: Using visual judgments, a total of 77 anterior open-bite cases in the postpubertal growth period were grouped as either morphogenetic, functional, or combination. The same sample was also grouped as either hyperdivergent, normodivergent, or hypodivergent using mandibular-plane angle and conventional cephalometry. Kappa analysis was used to test the agreement between the 2 methods of evaluation, and χ2 tests were used to analyze the distribution of cephalometrically grouped hyperdivergent, normodivergent, and hypodivergent cases among the visually assessed morphogenetic, functional and combination groups and vice versa. A κ score of 0.343 indicated a weak agreement between visual judgment and cephalometric methods of evaluation (P < .001).
Results: Despite the expectation that cases evaluated as hyperdivergent using cephalometry would be visually evaluated as morphogenetic, more than half of the cases assessed as hyperdivergent were in fact classified as functional.
Conclusions: These findings highlight the inadequacy of relying solely on cephalometric evaluation to classify open bite.Abstract
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DOI: 10.2319/022107-85.1
Objective: To investigate the laterality of the normal asymmetry of the human face, examining differences in laterality in relation to sex, growth stage, and skeletal classification.
Materials and Methods: A total of 1800 Japanese subjects (651 males and 1149 females; mean age, 15 years 3 months; range, 4 years 2 months to 59 years 11 months) were selected. Individuals in the sample were categorized according to sex, one of three growth stages, and one of three skeletal patterns. Differences in length between distances from the points at which ear rods were inserted to the facial midline and the perpendicular distance from the soft-tissue menton to the facial midline were measured on a frontal facial photograph. Subjects with a discrepancy of more than 3 standard deviations of the measurement error were categorized as having left- or right-sided laterality.
Results: Of subjects with facial asymmetry, 79.7% had a wider right hemiface, and 79.3% of those with chin deviation had left-sided laterality. These tendencies were independent of sex, age, or skeletal jaw relationships. In this regard, during pubertal growth, the proportion of subjects with wider right hemiface decreased (P < .0001), whereas the proportion of those with a wider left hemiface increased (P < .01), despite a consistent tendency for right-sided dominance.
Conclusion: These results suggest that laterality in the normal asymmetry of the face, which is consistently found in humans, is likely to be a hereditary rather than an acquired trait.Abstract
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DOI: 10.2319/041207-186.1
Objective: To quantify the changes in the nose after bimaxillary surgery to correct skeletal Class III malocclusion and to test the hypothesis that there is no change in the nasal width following bimaxillary surgical correction of skeletal Class III when a nasal cinch is properly used.
Materials and Methods: Sixty-five adult Korean skeletal Class III patients who had received maxillary advancement/impaction and mandibular set-back surgery in conjunction with an alar base cinch suture were evaluated. The anthropometric variables of the nasal region were measured directly on the soft-tissue surface before and 6 months after surgery.
Results: After surgery, the alar width and alar base width had increased significantly (P < .001), while the nasal tip projection decreased (P < .001). The nostril morphology also showed widening (P < .001). There was a trend for females with a narrow alar width presurgically to have a larger amount of nasal widening compared with those with a broader alar width (P < .05).
Conclusion: There is a high probability of nasal and nostril widening after bimaxillary surgery for skeletal Class III malocclusion in Koreans despite the careful performance of alar cinch suture. Nevertheless, the authors believe that alar cinch suture was positive in limiting the nasal widening to the minimum and would consider routine application during bimaxillary surgery for skeletal Class III especially for female patients with a narrow nose who are susceptible to these changes.Abstract
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DOI: 10.2319/013007-48.1
Objective: To investigate the cranial base configuration in skeletal Class III patients to clarify the conflicting findings from literature.
Materials and Methods: Initial lateral radiographs of 54 skeletal Class III patients and 54 matched controls (Class I, II/1, II/2) aged 14 to 24 years were analyzed retrospectively for 21 cephalometric basicranial variables and jaw lengths relative to anterior cranial base length.
Results: In contrast to overall cranial base length, the anterior (N-S) and posterior (S-Ba, S-Ar) sections failed to show a significant reduction in Class III patients. The significantly more acute angles Ca-S-Ba and Se-S-Ba reflected increased cranial base flexure. Resulting anterior condylar displacement was shown by significant reduction of Se-S-Cd and Ar-Ca. Relative mandibular length was significantly increased.
Conclusions: Decreased basicranial angulation associated with Class III mandibular protrusion was clearly confirmed for skeletal Class III patients. Overall shortening of the cranial base apparently resulted from various minor alterations. The results are compatible with the deficient orthocephalization hypothesis of Class III morphogenesis. The basicranial-maxillary relationship in skeletal Class III remains unclear.Abstract
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DOI: 10.2319/031607-136.1
Objective: To describe the dental arch changes occurring after adolescence through the sixth decade of life.
Materials and Methods: Longitudinal dental casts from 40 patients (20 male and 20 female) were digitized and analyzed. Measurements were recorded after the presumed cessation of circumpubertal growth (T1), at approximately 47 years of age (T2), and at least one decade later (T3) were compared.
Results: The majority of the measurements were found to have a significant time effect, demonstrating at least some level of change throughout the aging process (T1–T3). Exceptions to this observation were the posterior maxillary arch width measurements, mandibular intermolar and interpremolar (as measured at the second premolars) widths, the maxillary incisor irregularity index, overjet, overbite, and curve of Spee. The T1–T3 changes reflected for the most part the T1– T2 changes, while the T2–T3 changes affected overall modifications only for the mandibular intercanine width and maxillary depth, as measured at the second premolars. All changes reflected a decrease in arch width, depth, and perimeter, with a significant increase in the mandibular incisor irregularity index.
Conclusions: The dental arches continue to change and adapt throughout life and into the sixth decade, though the degree of change decreases with time.Abstract
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DOI: 10.2319/101106-417.1
Objective: To investigate the effects of a low calcium diet on maxillofacial development by evaluating Bone Mineral Content (BMC) in the lower alveolar bones, femurs, and tibias and by performing cephalometry on growing rats.
Materials and Methods: Thirty 5-week-old male Wistar rats were randomly divided into 3 groups; the control group (n = 10) was given standard diet for 6 weeks, the low calcium/standard diet group (n = 10) was given a calcium-restricted diet for the first 4 weeks, and then a standard diet for the following 2 weeks, and the low calcium diet group (n = 10) was given the calcium-restricted diet for 6 weeks. After the rats were euthanized, heads and legs were fixed and cephalometry was performed. Next, mandibles, femurs and tibias were digitally photographed and the BMC was evaluated using our newly developed software.
Results: The BMC was decreased in all of the bone samples from the two groups that received restricted calcium. In the low calcium/standard diet group, the BMC recovered the most in the tibias and least in the lower alveolar bones. Development of the mandibles in the anterior-posterior direction was accelerated, while that in the superior-inferior direction was inhibited in those rats.
Conclusion: The BMC reduction following calcium deficiency in the lower alveolar bone hardly recovers, so prevention is important. Development of the mandible in a superior-inferior direction is inhibited while that in an anterior-posterior direction is accelerated due to a calcium-restricted diet.Abstract
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DOI: 10.2319/012007-29.1
Objective: To clarify the expression of Bcl-2 and Bax following forward mandibular positioning (FMP) in the condylar chondrocytes of rabbits.
Materials and Methods: Sixty rabbits at 8 weeks of age were randomly allocated to the experimental group (n = 36) and control group (n = 24). Rabbits in the experimental group were induced to FMP by a functional appliance. Six rabbits from the experimental group and four from the control group were sacrificed after 3 days and 1, 2, 4, 8, and 12 weeks, respectively. All the right temporomandibular joints (TMJs) were collected and the expression of Bcl-2 and Bax was evaluated by immunohistochemical staining.
Results: The results showed the expression pattern of Bcl-2 and Bax during 12 weeks after FMP. The expression of Bcl-2 reached the highest level at 1 week, whereas Bax reached its maximal expression after 4 weeks. Subsequently, the expression of Bcl-2 and Bax gradually decreased. The ratio of Bcl-2/Bax began to decrease 3 days after FMP and continued to decline until 12 weeks.
Conclusions: FMP with functional appliances could change the expression of Bcl-2 and Bax, which is related to apoptosis in condylar chondrocytes.Abstract
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DOI: 10.2319/022807-104.1
Objective: To test the null hypothesis that American blacks do not have a higher frequency of extra permanent teeth than whites.
Materials and Methods: Panoramic radiographs of adolescent orthodontic patients, either American whites (n = 1100) or American blacks (n = 600), were reviewed systematically.
Results: The frequencies of supernumerary incisors, premolars, and molars were each significantly more common in blacks. While incisors are the most common extra teeth in whites (and extra molars are least common), just the opposite ranking occurs in blacks. Overall, the odds ratio was 8.8 (95% confidence limits = 3.9, 20.0), confirming that American blacks are significantly more likely (almost 9 times more likely) to possess extra permanent teeth than American whites.
Conclusions: The hypothesis is rejected. Both the frequencies and the patterns of extra permanent teeth are significantly different in blacks and whites, suggesting different frequencies of the relevant (but unidentified) factors governing the developmental mechanisms that result in hyperdontia.Abstract
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DOI: 10.2319/022307-89.1
Objective: To test the hypothesis that there is no difference in the dimensions of the upper and lower dental arches in Class II division 1 malocclusion with a mandibular deficiency compared to normal Class I occlusion dental arches.
Materials and Methods: Photocopies of the dental arches of 48 patients exhibiting Class II division 1 malocclusion with mandibular deficiency and of 51 individuals with normal occlusion were compared. Mandibular deficiency was diagnosed clinically. All 99 individuals were in the permanent dentition. The ages of the subjects ranged from 11 years 4 months to 20 years (mean age = 12 years 5 months).
Results: When compared to subjects with normal occlusion, the upper dental arches of the Class II division 1 patients presented reduced transverse dimensions and longer sagittal dimensions while the lower arches were less influenced.
Conclusion: The hypothesis is rejected. Significant differences are present between the dimensions of the upper and lower dental arches in Class II division 1 malocclusion (with a mandibular deficiency and in the permanent dentition) compared to normal Class I occlusion dental arches.Abstract
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DOI: 10.2319/040107-161.1
Objectives: To test the hypothesis that there is no difference between the actual mesiodistal root angulation and the mesiodistal root angulation as measured on the panoramic radiograph.
Materials and Methods: A typodont dentition was set up into a Class I occlusion. Wire struts were placed on the buccal surface of each tooth to represent their long axes. The dentition was fixed into a natural skull for imaging. The radiographic and true mesiodistal angulation of each tooth to a horizontal reference plane (the arch wire) was measured using a coordinate measuring machine (CMM). The mesiodistal root positions were then altered to a more mesial and then more distal position and the measurements were repeated.
Results: Only 26.7% of the radiographic root angulations were within the clinically acceptable angular variation range of ±2.5°. The greatest variation in the upper arch occurred in the canine-premolar area where the roots were projected as being more divergent. The greatest variation in the lower arch occurred in the lateral incisor-canine region where these roots were projected as being more convergent. The extent of radiographic distortion is statistically greater in the lower arch than in the upper arch in the ideal (P ≤ .05) and distal (P ≤ .01) root positions.
Conclusions: The hypothesis is rejected. There is a clinically significant variation between the radiographic and the true root angulations recorded. Caution is advised when interpreting mesiodistal root angulation using this radiograph.Abstract
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DOI: 10.2319/050207-212.1
Objective: To assess the prevalence, intensity, and extent of the impacts on daily performances related to wearing different types of orthodontic appliances.
Materials and Methods: A total of 1657 students, 15 to 16 years old, were randomly selected from those attending all secondary schools in Bauru, São Paulo, Brazil. Only those wearing orthodontic appliances at the time of the survey were included. Face-to-face structured interviews were done to collect information about impacts on quality of life related to wearing orthodontic appliances, using the Oral Impact on Daily Performances (OIDP). Adolescents were also clinically examined to assess the type of orthodontic appliance they were wearing. Comparisons, by type of orthodontic appliance and covariables, were performed using nonparametric statistical tests.
Results: Three hundred fifty-seven adolescents (36.1% boys and 63.9% girls) undergoing orthodontic treatment participated in the study. The prevalence of condition-specific impacts related to wearing orthodontic appliances was 22.7%. Among adolescents with impacts related to wearing orthodontic appliances, 35.8% reported impacts of severe or very severe intensity and 90.1% reported impacts on only one daily performance, commonly eating or speaking. The prevalence, but not the intensity or the extent, of condition-specific impacts differed by type of orthodontic appliance (P = .001).
Conclusions: One in four Brazilian adolescents undergoing orthodontic treatment reported side effects, specific impacts on daily living, related to wearing orthodontic appliances. Such impacts were higher among adolescents wearing fixed rather than removable or a combination of fixed and removable orthodontic appliances. This information could help to inform patients about the frequency and intensity of sociodental impacts during the course of their treatment.Abstract
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DOI: 10.2319/040207-165.1
Objective: To investigate by behavioral methods the relationship between emotional stress and pain during experimental tooth movement in rats.
Materials and Methods: Sixteen male Sprague-Dawley rats (210 to 250 g) were divided into two groups. The experimental group was treated with an active Ti-Ni appliance, and the control group received a passive appliance. A force of 20 gf was delivered by the active appliance between the maxillary first and second molars for 3 days. During this period the rat's behavior was evaluated eight times by means of open-field test and resistance-to-capture test. The specific parameters of animal activity were facial grooming, rearing, and locomotor activity, movement into the center of the open field, and response to capture.
Results: Parameters related to stress and pain were higher in the group carrying active appliance, compared to the group with a passive appliance. Statistically significant differences in stress-related behavior between control and experimental groups were found 8 hours after placing the appliance and were most evident on the second day. Pain-related behavior was significantly greater in the experimental group than in the control group at 24 hours.
Conclusions: The increase in emotional stress evoked by orthodontic tooth movement may precede the appearance of periodontal pain.Abstract
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DOI: 10.2319/020207-51.1
Objective: To investigate how the preapplication of orthodontic forces to the donor teeth affects the periodontal healing after transplantation.
Materials and Methods: The orthodontic force (1.5 cN) was applied to the maxillary right molars of 6-week-old male Spraque-Dawley rats (n = 21) in the experimental side, and the left side of the same animals was used as the control. After 7 days, both right and left maxillary second molars were extracted or replanted. Periodontal conditions were evaluated in the histological specimens 7 days after applying orthodontic force (before and after extraction) and 14 days after replantation.
Results: The application of orthodontic force for 7 days significantly increased the periodontal ligament (PDL) space and also the width of the alveolar socket, which resulted in a rich attached PDL to the root surface of the extracted teeth. Significantly more root resorption was also detected in the control side without preapplication of orthodontic force 14 days after replantation. This root resorption might involve in the disruption of the PDL.
Conclusion: These results suggested that the preapplication of orthodontic force to the donor teeth increased the PDL width and eased the extraction, which might decrease root resorption after replantation.Abstract
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DOI: 10.2319/052007-240.1
Objective: To test the hypothesis that there is no difference in the effect of different continuous moderate to very heavy forces on root resorption or amount of tooth movement.
Materials and Methods: In the study, 10, 25, 50 and 100 g mesial force were applied to the maxillary first molars of rat using nickel titanium closed-coil springs for 3 days, 14 days, and 28 days. The molars were extracted and the surface areas of the root resorption craters were measured using scanning electron microscope. The depths of the root resorption craters were measured using a three-dimensional laser scanning microscope. Tooth movement of the maxillary first molar was measured in relation to the maxillary second molar on digitized lateral cephalometric radiographs.
Results: Three days after force application, the tooth movement was not proportionally related to force magnitude. However, 14 days of force application resulted in significantly more tooth movement in the 10, 25, and 50 g force groups than in the 100 g force group. A force application of 10 g produced significantly more tooth movement at 28 days than all the other three force applications. The largest and deepest resorption craters were observed in the disto-buccal root followed by disto-palatal, middle-buccal, middle-palatal, and mesial root. Root resorption and tooth movement increased over time from 3 to 28 days. As heavier forces were applied, greater root resorption occurred.
Conclusion: The hypothesis is rejected. The light mesially oriented forces, as applied in this study, produced more tooth movement and less root resorption compared with heavier forces.Abstract
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DOI: 10.2319/053007-259.1
Objective: To test the null hypothesis that the resin base and the resin hybrid glass ionomer base adhesives do not cause inflammation after contacting primary human gingival fibroblasts in vitro.
Materials and Methods: The resin base and resin hybrid glass ionomer base adhesives were used to treat human gingival fibroblasts to evaluate the survival rate using MTT colorimetric assay to detect the level of cyclooxygenase-2 (COX-2) mRNA by reverse transcription polymerase chain reaction (RT-PCR) technique and COX-2 protein expression using Western blot analysis. The results were analyzed using one-way analysis of variance (ANOVA). Tests of differences of the treatments were analyzed using the Tukey test and a value of P < .05 was considered statistically significant.
Results: The paste and primer of the resin base adhesive and the liquid of glass ionomer adhesive showed decreasing survival rates after 24 hours of treatment (P < .05). All orthodontic adhesives induced COX-2 protein expression in human gingival fibroblasts. The exposure of quiescent human gingival fibroblasts to adhesives resulted in the induction of COX-2 mRNA expression. The investigations of the time-dependent COX-2 mRNA expression in adhesive-treated human gingival fibroblasts revealed different patterns.
Conclusions: The hypothesis is rejected. For orthodontic patients with gingival inflammation, except for those with oral hygiene problems, the activation of COX-2 expression by orthodontic adhesive may be one of the potential mechanisms.Abstract
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DOI: 10.2319/030207-109.1
Objective: To compare the system of forces acting on curvature and preactivated V-bends in titanium T-loop springs (TTLSs) made of 0.017- × 0.025-inch TMA (titanium molibdenium alloy) wire.
Materials and Methods: Pictures of TTLSs preactivated by curvature and V-bends were inserted in the LOOP software program to design both TTLSs. Symmetry was assured using the program. Both TTLSs used the same amount (length) of wire and had the same angulation between their anterior and posterior extremities when passive. The loops were activated 7 mm, and forces and moments were registered after each 0.5 mm of deactivation. The brackets were at the same height, separated by 23 mm and angulated 0°.
Results: The preactivated curvature TTLS delivered horizontal forces ranging from 34 gF to 456 gF, while the TTLS preactivated by V-bends delivered forces ranging from 54 gF to 517 gF. The forces decreased more (30 gF vs 33 gF) with every 0.5 mm of activation on the preactivated V-bend TTLS than on the preactivated curvature TTLS. Vertical forces were low and clinically insignificant for both TTLSs. The moment to force (MF) ratios were systematically higher on the preactivated curvature than on the preactivated V-bend TTLS (from 5.8 mm to 38.8 mm vs 4.7 mm to 28.3 mm).
Conclusions: Although both loops show symmetrical moments in their anterior and posterior extremities and can be used for group B anchorage, the curvature preactivated TTLS delivers lower horizontal forces and higher MF ratios than the acute preactivated V-bend TTLS.Abstract
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DOI: 10.2319/052707-250.1
Objective: To test the hypothesis that fluoride prophylactic agents do not affect the fracture strength and fracture morphology of the tie-wing complex of ceramic brackets.
Materials and Methods: The fracture strength of the distal incisal tie-wing of two polycrystalline brackets, Clarity and Mystique, and a monocrystalline bracket, Inspire, was measured after the brackets were exposed to either Prevident, Phos-flur gel, or distilled water (control). Scanning electron microscopy was used to qualitatively evaluate the tie-wing intact and fractured surfaces.
Results: A two-way analysis of variance and Fisher-Hayter post hoc test, α = .05, indicated a significant decrease in tie-wing fracture strength following both fluoride treatments when compared with the distilled water control only with the monocrystalline bracket. None of the bracket brands exhibited any qualitative differences in the tie-wing intact or fracture surfaces as a function of fluoride treatment.
Conclusions: The hypothesis is rejected. Based on the results, using topical fluoride agents with monocrystalline brackets might be contraindicated because of increased tie-wing fracture susceptibility.Abstract
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DOI: 10.2319/022307-90.1
Objective: To compare rebonding of orthodontic brackets based on the hypothesis that no difference would be found between the adhesive systems with respect to shear bond strength, mode of failure, and clinical failure rates.
Materials and Methods: The three adhesive systems included two self-etch primers (Transbond and M-Bond) and a conventional phosphoric acid etch (Rely-a-Bond). The sample size was 20 premolars for each adhesive system. The shear bond strength was tested 24 hours after bracket bonding with the bonding/debonding procedures repeated two times after the first debonding. Bond strength, adhesive remnant index (ARI), and failure sites were evaluated for each debonding. Statistical analysis consisted of a two-way analysis of variance (ANOVA) followed by Scheffè analysis. The clinical portion evaluated 15 patients over a 12-month period.
Results: The mean shear bond strengths after the first, second, and third debondings for Rely-a-Bond were 8.4 ± 1.8, 10.3 ± 2.4, and 14.1 ± 3.3 MPa, respectively; for Transbond 11.1 ± 4.6, 13.6 ± 4.5, and 12.9 ± 4.4 MPa, respectively; and for M-Bond 8.7 ± 2.7, 10.4 ± 2.4, and 12.4 ± 3.4 MPa, respectively. After the three debondings the mean shear bond strength increased significantly from the first to the third debonding for Rely-a-Bond and M-bond (P ≤ .001), but did not change for Transbond (P = .199).
Conclusions: The original hypothesis is not rejected. The two self-etching primers showing higher or comparable bond strength to the conventional phosphoric etch with less adhesive remnant on the enamel surface after the first debonding. With repeated bonding/debonding, the differences in the bond strength, ARI, and failure site were not significantly different. There was no difference in the clinical performance of the three adhesive systems (P = .667).Abstract
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DOI: 10.2319/022707-102.1
Objective: The hypothesis of this two-part study is that adhesive systems for bonding orthodontic brackets (ie, two self-etch primers [Transbond and M-Bond] and a conventional phosphoric acid etch [Rely-a-Bond]) would show a difference with respect to rebonded enamel surface morphology and chemical composition.
Materials and Methods: This study examined the enamel surface before and after debonding with scanning electron microscopy and the enamel surface chemical composition for the elements Ca, P, O, F, Si, and C using x-ray photoelectron spectroscopy.
Results: The etching of the two self-etch groups is less aggressive and less uniform than that of phosphoric acid. The change in the concentration of C indicated that the separation of the bracket from the enamel surface is at the resin-enamel interface for the phosphoric acid–etched adhesive and a mixed mode involving the enamel-resin-bracket interfaces for the self-etching systems. F release appears to occur for Transbond but not for M-Bond.
Conclusions: The results confirm the original hypothesis that differences in adhesive systems are manifested in less aggressive etches and less adhesive left on the enamel surface for the self-etching adhesive systems.Abstract
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DOI: 10.2319/010707-6.1
Objective: To determine the bond failure pattern and time to first bond failure at an orthodontic clinic.
Materials and Methods: The study included 63 subjects meeting the study criteria. A total of 1074 brackets (Roth prescription 0.022 slot) were bonded to incisors, canines, and premolars using a no-mix adhesive (Unite, 3M Unitek). The survival and failure rates of the brackets were evaluated by tooth position in the dental arch, sagittal occlusal relationship, and gender of the patients. Overall bracket survival rates were estimated using the Kaplan-Meier test.
Results: The total percentage of bond failure was 17.87%. The mean survival time for the sample was 235 days (SE = 32.27 days). Significantly higher failure rates were observed for posterior than anterior teeth (P < .05) and in the Class II division 2 malocclusion group than other malocclusion groups (P < .05). No difference was observed between dental arches or genders. However, in terms of survival time, the difference was marginally significant for gender (P = .051)
Conclusion: For 1074 brackets bonded with a no-mix adhesive system in 63 patients, the mean time until first bracket failure was 235 days. The overall failure rate of brackets was 17.87%.Abstract
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DOI: 10.2319/022207-88.1
Objective: To determine the degree of cure of a light-cured resin-modified glass ionomer (RMGI) under molar bands compared with a light-cured resin and a dual-cured resin.
Materials and Methods: The 3 cements used were Fuji Ortho LC, Eagle Spectrum resin, and Variolink II dual-cure. Each sample was indirectly light cured for 20 seconds (10 seconds occlusally, 10 seconds cervically) under sections of molar bands, and the degree of cure was evaluated with micro-MIR FTIR spectroscopy.
Results: The RMGI exhibited a significantly higher mean degree of cure (55.31%) than both of the resins (Eagle 19.23%; Variolink II, 25.42%), which did not differ significantly at α = .05 level of significance.
Conclusion: Higher degree of conversion can be obtained from RMGIs under molar bands compared with composite resin adhesives provided the proper curing technique is used.Abstract
Case Report
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DOI: 10.2319/052307-248.1
Malocclusions with a hyperdivergent vertical facial pattern are often difficult to treat without a combined surgical/orthodontic approach. The aim of this article is to describe a nonsurgical approach to the treatment of a high-angle Class II malocclusion in a growing patient. Some fundamental aspects, such as correct diagnosis, treatment timing, favorable mandibular growth pattern, and patient compliance, proved to be critical to correct the severe dentoskeletal disharmony.Abstract
Review
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DOI: 10.2319/030207-108.1
Objective: To assess the scientific evidence on the effectiveness of early orthopedic treatment in Class III subjects.
Materials and Methods: A literature survey was performed by applying the Medline database (Entrez PubMed). The survey covered the period from January 1966 to December 2005 and used the Medical Subject Headings (MeSH). The following study types that reported data on the effects of Class III treatment with orthopedic appliances (facial mask, chincup, FR-3) on intermaxillary sagittal and vertical relationships were included: randomized clinical trials (RCTs), and prospective and retrospective longitudinal controlled clinical trials (CCTs) with untreated Class III controls.
Results: The search strategy resulted in 536 articles. After selection according to criteria for inclusion and exclusion, 19 articles qualified for the final review analysis. One RCT and 18 CCTs were retrieved.
Conclusion: The quality standard of the retrieved investigations ranged from low (four studies) to medium/high (five studies). Data derived from medium/high quality research described over 75% of success of orthopedic treatment of Class III malocclusion (RME and facial mask therapy) at a follow-up observation 5 years after the end of orthopedic treatment.Abstract
Guest Editorial
In Phoenix, Arizona, during three comfortable days in January 2008, Ormco Corporation hosted the 8th annual Damon Forum to celebrate its flagship orthodontic product line, the Damon System. At the heart of the system is an interesting self-ligating bracket with an assortment of prescribed wires and auxiliaries. The progenitor of these products is Dwight Damon, an affable orthodontist from the state of Washington. Many of the features of his appliances were envisioned and developed by Dr Damon some 18 years ago as the result of his experiences and frustrations in clinical practice. Over the past 8 years, he has parlayed
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