bluuebunny/crossref_metadata_2025 huggingface dataset:
Arch Widths in Class II-2 Adults Compared to Adults with Class II-1 and Normal Occlusion
Authors: Huth Joel , Staley Robert Newton , Jacobs Richard , Bigelow Harold , Jakobsen Jane
Published: May 2007

Objective: To compare (1) arch widths in adults with Class II division 2 (II-2), Class II division 1 (II-1), and Class I normal occlusions, (2) genders, (3) gender dimorphism, (4) differences between maxillary and mandibular arch widths, and to (5) develop adult norms for arch widths.

Materials and Methods: Subjects were white Americans with no history of orthodontic treatment. Arch width dimensions measured were: intercanine, intermolar, and molar alveolar in both arches. Analysis of variance (ANOVA) and Duncan's test were used to compare groups.

Results: Comparison of pooled genders showed the II-2 group had maxillary arch widths significantly smaller than the normal occlusions and significantly larger than the II-1 group. All groups had similar mandibular intercanine and alveolar widths. The II-2 and II-1 groups had similar mandibular intermolar widths, both significantly smaller than normal occlusions. The II-2 group had a maxillary/mandibular intermolar difference significantly smaller than the normal occlusions, and significantly less negative than the II-1 group. Gender comparisons in two of six widths showed normal and II-2 male subjects were similar, and in six of six widths normal and II-2 female subjects were similar; in five of six widths II-2 and II-1 male and female subjects were similar. Gender dimorphism occurred in five of six widths in normal occlusions, four of six widths in II-2, and one of six widths in II-1.

Conclusions: Arch width dimensions of II-2 subjects were intermediate between normal and II-1 occlusions. In both Class II malocclusions, the process that narrows arch widths was more pronounced in male than in female subjects.
Apoptosis of Growth Plate Chondrocytes Occurs through a Mitochondrial Pathway
Authors: Teixeira Cristina C. , Costas Aida P. Padron , Nemelivsky Yelena
Published: May 2007

Objective: To determine the role of mitochondria in chondrocyte apoptosis induced by inorganic phosphate (Pi).

Materials and Methods: Chondrocytes isolated from the growth plates of chick embryo tibia were treated with Pi in serum-free media; chondrocyte viability, mitochondrial membrane potential, cytochrome c release from mitochondria, caspase 3 activity, endonuclease activity, and DNA fragmentation were investigated.

Results: Exposure to Pi for 24 hours induced apoptosis in growth plate chondrocytes through a pathway that involved loss of mitochondrial function, release of cytochrome c into the cytoplasm, increases in caspase 3 and endonuclease activities, and fragmentation of DNA.

Conclusions: This study suggests that mitochondria are important players in Pi-induced apoptosis.
Antimicrobial Effectiveness of a Highly Concentrated Chlorhexidine Varnish Treatment in Teenagers with Fixed Orthodontic Appliances
Authors: Attin Rengin , Ilse Anika , Werner Carola , Wiegand Annette , Attin Thomas
Published: May 2007

Objective: To evaluate the recolonization pattern of Mutans streptococci (ms) on densely colonized teeth with fixed orthodontic appliances after treatment with a highly concentrated (36%) chlorhexidine varnish.

Materials and Methods: Healthy subjects (n = 19) with fixed orthodontic appliances and high bacterial ms counts in saliva were recruited. In order to establish a baseline registration, plaque adjacent to brackets was sampled and cultivated on Dentocult® strips. Following professional tooth cleaning, chlorhexidine varnish was applied on all teeth for 8 minutes. The degree of recolonization with ms was assessed 2 weeks after varnish application in plaque around the brackets. For statistical analysis, the data were subjected to a repeated measures design.

Results: After 2 weeks, ms counts were reduced as compared to baseline values. However, the reduction only weakly met statistical significance (P = .049).

Conclusions: The application of a highly concentrated chlorhexidine varnish in patients with fixed orthodontic appliances does not result in a distinct reduction of ms numbers 2 weeks after treatment.
Characteristics of Movement of the Lips, Tongue and Velum during a Bilabial Plosive
Authors: Inoue Maristela Sayuri , Ono Takashi , Honda Ei-ichi , Kurabayashi Tohru
Published: May 2007

Objective: To obtain dynamic images of articulators using a magnetic resonance imaging (MRI) movie and to clarify the relationships among the articulators.

Materials and Methods: The subjects consisted of 10 volunteers. Custom-made circuitry was connected to an MRI apparatus to enable an external trigger pulse to control the timing of the scanning sequence and to provide an auditory cue for synchronization of the subject's utterance. The subject repeated a bilabial plosive, and the run was measured using a gradient echo sequence with a repetition time of 30 ms. Several variables were defined to delineate the individual movements of articulators and to determine the temporal relationships among them.

Results: It was found that (1) the change in these variables showed distinctive waveforms; (2) mean values of the standard deviations for these variables were relatively small; and (3) the movement of the velum was significantly correlated with those of the lips and the anterior part of the tongue, but not with the posterior part of the tongue.

Conclusions: These results suggest that (1) articulatory movements were clearly recorded using an MRI movie, and (2) there seems to be a central mechanism for controlling articulators, and the level of coupling may be associated with the place of articulation.
Spatial Relationships between the Mandibular Central Incisor and Associated Alveolar Bone in Adults with Mandibular Prognathism
Authors: Yamada Chiaki , Kitai Noriyuki , Kakimoto Naoya , Murakami Shumei , Furukawa Souhei , Takada Kenji
Published: May 2007

Objective: To examine if there was any correlation between the labio-lingual inclinations of the mandibular central incisor and the associated alveolar bone, and to investigate the labio-lingual position of the mandibular central incisor root apex in the associated cancellous bone in adults with untreated mandibular prognathism.

Materials and Methods: High-resolution computed tomography images of the mandible were recorded in 20 adult patients with mandibular prognathism. The labio-lingual inclinations of a central incisor and its associated alveolar bone, the thickness of the associated cancellous bone, and the distance from the central incisor root apex to the inner contour of both the labial and lingual cortical plates were measured. Correlations and differences between the measured variables were tested for statistical significance.

Results: The labio-lingual inclination of the central incisor significantly correlated with the labio-lingual inclination of the associated alveolar bone, the thickness of cancellous bone, and the distance from the central incisor root apex to the inner contour of the lingual cortical bone. The distance from the central incisor root apex to the inner contour of the labial cortical plate of bone was significantly smaller than that to the lingual cortical plate.

Conclusions: In adults with untreated mandibular prognathism, when the mandibular central incisor was more lingually inclined, the associated alveolar bone was also more lingually inclined and thinner. The mandibular central incisor root apex was closer to the inner contour of the labial cortical bone than to the lingual cortical bone.
Dentofacial Characteristics of Chinese Obstructive Sleep Apnea Patients in Relation to Obesity and Severity
Authors: Hou Huie Ming , Hägg Urban , Sam Kim , Rabie A. B. M. , Wong Ricky W. K. , Lam B. , Ip Mary S.
Published: May 2007

Objective: To evaluate dentofacial characteristics in relation to obesity and degree of severity of obstructive sleep apnea (OSA) in male Chinese patients and to elucidate the relationship between demographic parameters (age, body weight, height, and body mass index [BMI]) cephalometric parameters and OSA in these subjects.

Materials and Methods: Lateral cephalograms of 121 Chinese male patients in natural head posture were obtained. Based on BMI value, the patients were divided into three groups. Based on apnea-hypopnea index (AHI) value, the patients were divided into a mild-to-moderate and a severe group.

Results: The hyoid position and soft palate length were significantly different among the three obesity groups. Soft palate length was significantly longer (P < .01) in the severe OSA group than in the mild-to-moderate OSA group. Tongue base was significantly more inferiorly placed (P < .05) in the severe OSA group than in the mild-to-moderate OSA group. Craniocervical extension was significantly increased (P < .05) in the severe OSA group. Statistically significant differences were found among the three obesity groups in mandibular length, mandibular body length, maxillary length, anterior cranial base length, and overbite. The multiple stepwise linear regression analysis identified body weight, lower posterior facial height, mandibular body length, craniocervical extension, and sella-hyoid distance as the significant predictive variables for AHI.

Conclusions: This study revealed the existence of craniofacial and upper airway soft tissue differences in relation to obesity and severity of OSA among male Chinese OSA patients. Body weight and certain cephalometric parameters were significant predictors of OSA in Chinese male subjects.
Incisal and Soft Tissue Effects of Maxillary Premolar Extraction in Class II Treatment
Authors: Tadic Nevenka , Woods Michael G.
Published: May 2007

Objective: This retrospective study was designed to show likely upper incisal and soft tissue lip changes accompanying Class II fixed appliance treatment with only two upper premolar extractions and to assess whether the lips, especially, are predictably and directly affected with such treatment.

Materials and Methods: Pretreatment and posttreatment lateral cephalograms and study casts from 61 growing Class II patients (aged 11 to 18 years; 39 division 1 and 22 division 2) were assessed. Upper and lower lip curve depths, nasolabial angle, and upper incisal position and angulation were all assessed and compared with changes in other cephalometric variables.

Results: A wide range of individual response in both lip and upper incisor behavior were noted. The observed soft tissue lip changes were most likely to be related to the preexisting morphology of the lips themselves, while upper incisal changes were mainly related to their own pretreatment positions and changes occurring with treatment in the underlying bony structures.

Conclusion: Orthodontic treatment involving the extractions of only two upper premolars is likely to result in a wide range of variation in lip and upper incisor behavior. The preexisting soft tissue morphology is likely to be the greatest determinant of lip behavior.
Hypodontia Patterns and Variations in Craniofacial Morphology in Japanese Orthodontic Patients
Authors: Endo Toshiya , Ozoe Rieko , Yoshino Sugako , Shimooka Shohachi
Published: May 2007

Objective: The purpose of this study was to explore the association of hypodontia patterns and variations in craniofacial morphology in Japanese orthodontic patients.

Materials and Methods: A total of 50 girls with hypodontia (the total group) were selected and categorized into anterior, posterior, and anterior-posterior groups according to the location of the congenitally missing teeth. By using the lateral cephalograms of each subject, 28 angular and 37 linear measurements were made. The cephalometric data were statistically analyzed and compared among the groups and with the Japanese cephalometric standards from 36 age-matched female subjects without hypodontia or malocclusion (the control group).

Results: Every hypodontia group showed shorter anterior and overall cranial base lengths, shorter maxillary length, greater retroclination and elongation of mandibular incisors, and a larger interincisal angle than the control group. The total and anterior-posterior groups especially exhibited a significantly more prognathic mandible, larger retroclination of maxillary incisors, and a more counterclockwise-rotated occlusal plane. Furthermore, these skeletal and dental deviations were more remarkable in the anterior-posterior group than in either the anterior or the posterior group. Anterior hypodontia exerted as much influence on craniofacial morphology as posterior hypodontia.

Conclusions: When orthodontic treatment is performed on patients with hypodontia, not only the number but also the distribution of missing teeth should be taken into consideration, though there was no significant difference in craniofacial morphology between anterior hypodontia and posterior hypodontia.
Lip-to-incisor Relationship and Postorthodontic Long-term Stability of Cover-bite Treatment
Authors: Lapatki Bernd G. , Baustert Dirk , Schulte-Mönting Jürgen , Frucht Sibylle , Jonas Irmtrud E.
Published: May 2007

Objective: To investigate the impact of a persisting high lip line and other potential relapse-inducing factors on long-term stability of orthodontic correction of retroinclined maxillary central incisors.

Materials and Methods: Thirty-one cover-bite (“Deckbiss”) patients with retroinclined maxillary central incisors and a deep frontal overbite were evaluated. The maxillary central incisor inclination was determined odontometrically with study models made pretreatment, posttreatment, and at a follow-up examination (mean posttherapeutic interval: 9.0 years). The lip-to-incisor relationship, the interincisal angle, and the anteroposterior maxillary central incisor position were measured on lateral cephalograms taken after active treatment.

Results: The relapse tendency of the orthodontic correction of the retroinclined maxillary central incisors displayed great interindividual variability with a range of posttherapeutic inclination change of −6.75° to +8.00°. Multiple regression analysis revealed an increased tendency for relapse in patients with (1) a high posttherapeutic (dorsal) lip line level combined with the maxillary central incisor and lower lip contact only in the incisal crown area (P < .01) and (2) a marked therapeutically induced inclination change of the maxillary central incisors (P < .05). Interrelations between the relapse of the corrected maxillary central incisors and other evaluated parameters were not statistically significant.

Conclusions: For maximum treatment stability, the elimination of an excessive overlap of the upper incisors by the lower lip should be regarded as one of the most important therapeutic objectives when treating this malocclusion.
Analysis of Sutural Strain in Maxillary Protraction Therapy
Authors: Holberg Christof , Mahaini Luai , Rudzki Ingrid
Published: May 2007

Objective: The goal of the study was to examine the strain in the sutures of the midface and the cranial base with maxillary protraction therapy and to clarify whether such stretching suggests a skeletal effect of the apparatus employed for that purpose.

Materials and Methods: Using a finite elements model, a maxillary protraction therapy was simulated with various force levels and vectors, and the strains appearing at the sutures (in μstrain) were measured at the midface and the cranial base. The simulation model we employed consisted of 53,555 individual elements; the simulated forces were 2 × 3 N and 2 × 5 N, while the vectors of the applied forces were in the anterior and anterior caudal direction.

Results: The maximum measured strains were on average below 10 μstrain, while higher values were measured only at the nasal bone and at the cranial base at the oval and spinous foramina with anterior directed force vectors (26.4 μstrain). With an anterior-caudal force vector, the measured values were usually lower.

Discussion: The measured strains were on average about hundredfold lower than the Frost thresholds (2000 μstrain). It does not seem probable that the strains occurring upon maxillary protraction therapy suffice to stimulate any additional bone growth.

Conclusion: The good clinical efficacy of maxillary protraction therapy is apparently based, for the most part, on dental effects, while its skeletal effects still remain doubtful.
Bimaxillary Protrusion in the Palestinian Population
Authors: Hussein Emad , Mois Mahmoud Abu
Published: May 2007

Objective: To study the prevalence of bimaxillary protrusion among Palestinians.

Materials and Methods: Cephalometric radiographs for 79 normal occlusion adult Palestinian university students were traced.

Results: The interincisal angle was decreased in the Palestinian women compared to the Caucasian means, but this had no impact on lip protrusion.

Conclusion: Relative to Caucasian cephalometric norms, Palestinians show no extraoral bimaxillary protrusion features, and therefore, these norms can be applied to Palestinian faces.
Effects of a Mandibular Lateral Shift on the Condyle and Mandibular Bone in Growing Rats
Authors: Liu Chang , Kaneko Sawa , Soma Kunimichi
Published: May 2007

Objective: To examine the effects of mandibular lateral shift on the growth and morphology of the condyle and mandibular bone in growing rats.

Materials and Methods: A maxillary resin plate was designed to displace 4-week-old rat mandibles 2 mm to the left during closure. The plate was cemented, and the rats were killed after 2, 4, 8, or 12 weeks. Gross dimensions of the condylar head were measured. Radiographic films of the mandibles were exposed, and selected measurements were made. The newly formed bone in the condyle was evaluated with periodic acid and Schiff's reagent (PAS) staining.

Results: The length of the condylar head was greater on the ipsilateral side compared with the contralateral side. The experimental rats developed an asymmetric mandible, shorter in horizontal dimension but longer in the vertical dimension on the ipsilateral side. The mandibular growth direction was also affected, with the mandible on the ipsilateral side growing in a more anterior and superior direction. The amount of newly formed bone was greater in the superior subchondral region but lower in the posterior subchondral region on the ipsilateral side compared with the contralateral side.

Conclusions: Mechanical stimuli delivered by a functional shift produce a series of morphological and histological responses in the condyle and lead to condylar and mandibular asymmetry in rats.
Herbst Treatment of Class II division 1 Malocclusions in Retrognathic and Prognathic Facial Types
Authors: Bock Niko , Pancherz Hans
Published: May 2007

Objective: The aim of this retrospective pilot study was to analyze and compare the short-term and long-term changes of Herbst treatment in Class II division 1 subjects of the retrognathic and prognathic facial type.

Materials and Methods: The subject material comprised 10 retrognathic (mean SNA = 74.5°, SNB = 70.4°, ML/NSL = 41.1°) and 16 prognathic (mean SNA = 86.7°, SNB = 81.5°, ML/NSL = 25.1°) Class II division 1 subjects treated with the Herbst appliance for an average period of 7 months. Lateral head films from before (T1), immediately after (T2), 12 months after (T3), and 39 months after (T4) Herbst treatment were analyzed with the SO-analysis (analysis of changes in sagittal occlusion) and standard cephalometrics.

Results: During the treatment period (T2–T1) the two facial type groups showed similar favorable changes for all variables. During the posttreatment periods of 12 months (T3–T2) and 39 months (T4–T2) recovering changes occurred. In the long-term, a tendency of more unfavorable growth changes was stronger (not significant) for retrognathic subjects than for prognathic subjects.

Conclusion: On a long-term basis, retrognathic subjects are prone to exhibit more unfavorable mandibular growth changes than prognathic subjects and, thus, might exhibit a greater risk for an occlusal relapse when a stable Class I occlusion is not attained after treatment.
Ultrasonographic Thickness of the Masseter Muscle in Growing Individuals with Unilateral Crossbite
Authors: Kiliaridis Stavros , Mahboubi Payam H. , Raadsheer Maarten C. , Katsaros Christos
Published: May 2007

Objective: To study the bilateral differences in the thickness of the masseter muscles in untreated individuals with lateral crossbite, as well as in subjects with successfully treated functional lateral crossbite, at least three years after the end of treatment.

Materials and Methods: Three groups of growing individuals were studied: (1) untreated group: 38 individuals with unilateral crossbite, (2) control group: 224 subjects without transversal malocclusions, and (3) treated group: 18 individuals with functional lateral crossbite, treated with a quad helix, and at least three years out of retention with all permanent teeth erupted. The thickness of the masseter muscle was measured bilaterally with ultrasonography, using a real time scanner with a 7.5 MHz linear array transducer.

Results: In the untreated group, the thickness of the masseter muscle on the crossbite side was statistically significantly thinner than the one on the normal side (P = .025). No statistically significant differences were found in the thickness of the masseter muscle between the left and the right side in the control group. In the treated group, no statistically significant differences were found in the thickness of the masseter muscle between the former crossbite side and the normal one.

Conclusion: The masseter muscle in untreated individuals with unilateral crossbite is thinner in the crossbite side when compared to the non-crossbite side possibly due to asymmetric activity of the masticatory muscles. Such an asymmetry in thickness of the masseter muscle could not be detected some years after the successful correction of the crossbite.
Microleakage beneath Ceramic and Metal Brackets Bonded with a Conventional and an Antibacterial Adhesive System
Authors: Arhun Neslihan , Arman Ayca , Çehreli Sevi Burçak , Arıkan Serdar , Karabulut Erdem , Gülşahı Kamran
Published: May 2007

Objective: To assess microleakage of a tooth-adhesive-bracket complex when metal or ceramic brackets were bonded with a conventional and an antibacterial self-etching adhesive.

Materials and Methods: Forty freshly extracted human premolars were randomly assigned to four equal groups and received the following treatments: group 1 = Transbond XT + metal bracket, group 2 = Transbond XT + ceramic bracket, group 3 = Clearfil Protect Bond + ceramic bracket, and group 4 = Clearfil Protect Bond + metal bracket. After photopolymerization, the teeth were kept in distilled water for 1 month and thereafter subjected to thermal cycling (500 cycles). Specimens were further sealed with nail varnish, stained with 0.5% basic fuchsin for 24 hours, sectioned and examined under a stereomicroscope, and scored for marginal microleakage for the adhesive-tooth and bracket-adhesive interfaces from incisal and gingival margins. Statistical analysis was accomplished by Kruskal-Wallis test and Mann-Whitney U-test with Bonferroni correction.

Results: All groups demonstrated microleakage between the adhesive-enamel and bracket-adhesive interfaces. A significant difference was observed among all groups (P < .05) for the microleakage between the bracket-adhesive interface. Metal brackets exhibited significantly more microleakage than did ceramic brackets between the bracket-adhesive interface with either of the adhesives. Clearfil Protect Bond exhibited results similar to Transbond XT. Clearfil Protect Bond may be a choice of adhesive in bracket bonding because of its antibacterial activity and similar microleakage results with the orthodontic adhesive.

Conclusions: Metal brackets cause more leakage between an adhesive-bracket interface, which may lead to lower clinical shear bond strength and white-spot lesions.
Longitudinal Evaluation of the Intermaxillary Relationship in Class III Malocclusions
Authors: Chen Fengshan , Terada Kazuto , Wu Liping , Saito Isao
Published: May 2007

Objective: To analyze the sagittal, vertical, and transverse relationship of the maxilla and mandible in Japanese girls with Class III malocclusions.

Materials and Methods: This longitudinal study utilized biannual posteroanterior and lateral cephalograms of 44 untreated subjects from age 8 to 14 years (Class I, 23 girls; Class III, 21 girls). Sagittal and vertical growths were analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms.

Results: There was no significant difference in sagittal intermaxillary relationships in Class III malocclusion from age 8 to 14 years, whereas significant difference in vertical and transverse intermaxillary relationships appeared with ages during this period. When comparing Class III to Class I malocclusions at the same age point, there were significant differences in sagittal and transverse intermaxillary relationships, whereas significant difference in vertical intermaxillary relationship appeared after 12 years of age.

Conclusion: The results suggest that the sagittal intermaxillary relationships in Class III malocclusions were established before 8 years of age and remained through puberty and that the vertical and transverse intermaxillary relationships in Class III malocclusions changed with ages from 8 to 14 years.
An Adult Bimaxillary Protrusion Treated with Corticotomy-Facilitated Orthodontics and Titanium Miniplates
Authors: Iino Shoichiro , Sakoda Sumio , Miyawaki Shouichi
Published: May 2007

We performed an orthodontic treatment combined with corticotomy and the placement of titanium miniplates in an adult patient who desired a shortened treatment period. The patient had an Angle Class I malocclusion with flaring of the maxillary and mandibular incisors. First, titanium miniplates were placed into the buccal alveolar bone of the maxilla for absolute orthodontic anchorage. Second, an edgewise appliance was applied to the maxillary and mandibular teeth. Then, the maxillary first premolars and mandibular second premolars were extracted. At the same time, a corticotomy was performed on the cortical bone of the lingual and buccal sides in the maxillary anterior as well as the mandibular anterior and posterior regions. Leveling was initiated immediately after the corticotomy. The extraction spaces were closed with conventional orthodontic force (approximately 1 N per side). The edgewise appliance was adjusted once every 2 weeks. The total treatment time was 1 year. Cephalometric superimpositions showed no anchorage loss, and panoramic radiographs showed neither significant reduction in the crest bone height nor marked apical root resorption. A corticotomy-facilitated orthodontic treatment with titanium miniplates might shorten an orthodontic treatment period without any anchorage loss or adverse effects.
Intraoral Maxillary Molar Distalization
Authors: Karlsson Ingela , Bondemark Lars
Published: May 2007

Objective: To evaluate the maxillary molar distalization and anchorage loss in two groups, one before (MD 1 group) and one after (MD 2 group) eruption of second maxillary molars.

Materials and Methods: After a sample size calculation, 20 patients were recruited for each group from patients who fulfilled the following criteria: no orthodontic treatment before distal molar movement, Class II molar relationship defined by at least end-to-end molar relationship, space deficiency in the maxilla, and use of an intra-arch NiTi coil appliance with a Nance appliance to provide anchorage. Patients in the MD 1 group were without any erupted second molars during the distalization period, whereas in the MD 2 group both the first and second molars were in occlusion at start of treatment. The main outcome measures to be assessed were: treatment time, ie, time in months to achieve a normal molar relation, distal movement of maxillary first molars, and anterior movement of maxillary incisors (anchorage loss). The mean age in the MD 1 group was 11.4 years; in the MD 2 group, 14.6 years.

Results: The amount of distal movement of the first molars was significantly greater (P < .01) and the anchorage loss was significantly lower (P < .01) in the group with no second molars erupted. The molar distalization time was also significantly shorter (P < .001) in this group, and thus the movement rate was two times higher.

Conclusions: It is more effective to distalize the first maxillary molars before the second molars have erupted.
Microleakage beneath Ceramic and Metal Brackets Photopolymerized with LED or Conventional Light Curing Units
Authors: Arıkan Serdar , Arhun Neslihan , Arman Ayça , Cehreli Sevi Burcak
Published: May 2007

Objective: To test the null hypotheses that (1) the type of light curing unit used (quartz-tungsten-halogen [QTH] or light-emitting diode [LED]) would not affect the amount of microleakage observed beneath brackets, and (2) the bracket type used (ceramic or metal) would not influence the amount of microleakage observed beneath brackets.

Materials and Methods: 40 freshly-extracted human premolars were randomly assigned into 4 bonding groups (n = 10/group): group 1, metal bracket + LED-cured Transbond XT; group 2, ceramic bracket + LED-cured Transbond XT; group 3, metal bracket + QTH-cured Transbond XT; and group 4, ceramic bracket + QTH-cured Transbond XT. The teeth were kept in distilled water for 1 month, and thereafter subjected to 500 thermal cycles. Then, specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 hours, sectioned, and photographed under a stereomicroscope. Microleakage was scored with regard to the adhesive-tooth interface and the bracket-adhesive interface at both incisal and gingival margins. Statistical analysis was accomplished by Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction.

Results: Microleakage was observed in all groups. When an LED curing unit was used for adhesive polymerization, ceramic brackets displayed significantly less microleakage than metal brackets in both tooth-adhesive and bracket-adhesive interfaces. When a QTH curing unit was used, ceramic brackets displayed significantly less microleakage than metal brackets in the bracket-adhesive interface in both gingival and incisal margins.

Conclusions: Ceramic brackets cured with LED units were the best combination, demonstrating the lowest microleakage scores.
Three Palatal Arches Used to Correct Posterior Dental Crossbites
Authors: Martinelli Fernando Lima , Couto Priscilla Sobral , Ruellas Antonio Carlos Oliveira
Published: May 2007

Objective: To assess the force, resilience, and elasticity modulus produced by the Coffin appliance, “W” arch, and quad-helix made with 0.032-inch and 0.036-inch stainless steel wire.

Materials and Methods: Two groups of 15 arches were made as Coffin appliances, two groups of 15 arches were made as “W” arches, and two groups of 15 arches were made as quad-helices. One group of each appliance was formed in 0.032-inch and one group in 0.036-inch stainless steel wire. All arches (6 groups of 15 each) were submitted to compression trials in the mechanical testing machine EMIC DL-10000, simulating 5-, 8-, 10-, and 12-mm activation. The force and resilience means received a one-way ANOVA statistical analysis.

Results: The results showed that the mechanical properties depended on the shape of the appliance, the diameter of the wire used, and the amount of activation.

Conclusions: The three appliances assessed produce appropriate forces for orthodontic treatment as long as they are correctly planned during clinical application.
Effect of Enamel Etching on Tensile Bond Strength of Brackets Bonded In Vivo with a Resin-reinforced Glass Ionomer Cement
Authors: Rosenbach Gabriella , Cal-Neto Julio Pedrae , Oliveira Silvio Rosan , Chevitarese Orlando , Almeida Marco Antonio
Published: May 2007

Objective: To evaluate the influence of enamel etching on tensile bond strength of orthodontic brackets bonded with resin-reinforced glass ionomer cement.

Materials and Methods: The sample group consisted of 15 patients who had indications for extraction of four premolars for orthodontic reasons, equally divided into two different groups according to bracket and enamel preparation. Brackets were bonded in vivo, by the same operator, using a split mouth random technique: Group 1 (control), phosphoric acid + Fuji Ortho LC; Group 2, Fuji Ortho LC without acid conditioning. The teeth were extracted after 4 weeks using elevators. An Instron Universal Testing Machine was used to apply a tensile force directly to the enamel-bracket interface at a speed of 0.5 mm/min. The groups were compared using a Mann-Whitney U-test and Weibull analysis.

Results: Mean results and standard deviations (in MPa) for the groups were: Group 1, 6.26 (3.21), Group 2, 6.52 (2.73). No significant difference was observed in the bond strengths of the two groups evaluated (P = .599).

Conclusions: Fuji Ortho LC showed adequate shear bond strength and may be suitable for clinical use.
Dentoskeletal Effects and “Effective” Temporomandibular Joint, Maxilla and Chin Changes in Good and Bad Responders to van Beek Activator Treatment
Authors: Ruf Sabine , Bendeus Margareta , Pancherz Hans , Hägg Urban
Published: May 2007

Objective: To assess possible differences in dentoskeletal effects and “effective” temporomandibular joint, maxilla, and chin changes between good and bad responders to van Beek activator treatment.

Materials and Methods: The subject material consisted of 20 consecutive normodivergent male Class II division 1 patients treated with a van Beek activator. Because of insufficient cooperation, four patients were excluded. Lateral head films were taken 6 months before treatment, at start of treatment, and after 12 months of treatment. The patients were placed into a good responder group (successful, n = 8) and a bad responder group (unsuccessful, n = 8). An overjet reduction ≥4 mm was considered successful.

Results: During the van Beek treatment period, the good responders showed a significantly larger improvement in overjet and molar relationship than did the bad responders. The good responders exhibited a significant posterior development of condylion, less anterior mandibular autorotation, retrusion of upper incisors, protrusion of lower incisors, distalization of maxillary molars, and a mesial movement of mandibular molars. No significant dental movements were seen in the bad responders.

Conclusions: Although van Beek activator treatment affected the direction of condylar growth, as well as the direction of maxilla and chin changes, it can be concluded that skeletal changes did not contribute to the Class II correction. Instead, overjet reduction during van Beek activator treatment was found to be due to a favorable dental reaction.
Tumor Necrosis Factor–α Levels during Two Different Canine Distalization Techniques
Authors: Karacay Seniz , Saygun Işıl , Bengi Ali Osman , Serdar Muhittin
Published: May 2007

Objectives: To compare levels of tumor necrosis factor (TNF)-α while applying continuous and heavy interrupted forces.

Materials and Methods: A hybrid retractor was used in the first group. In the second group, rapid canine distalization through periodontal distraction was performed. Gingival crevicular fluid samples were collected from the distal sides of the canine teeth before attaching the appliances and at 1 hour, 24 hours, and 1 week after the force was applied.

Results: In the hybrid reactor group, concentration of TNF-α decreased at 1 week according to 24-hour measurements. In the rapid canine distalization group, it severely increased at 1 hour. In the evaluation of between-group differences, significantly higher values were determined in the rapid canine distalization group at 1 hour and 1 week.

Conclusions: Heavy interrupted force induces a rapid release of TNF-α, and the tissue response continues for a longer time period. To avoid the harmful effects of heavy interrupted force, there might be feedback mechanisms that prevent the mediators from increasing excessively.
Niche expansion of a cryptic primate,Callimico goeldii, while in mixed species troops
Authors: Porter Leila M. , Garber Paul A.
Published: May 2007

We examined the effects of polyspecific associations on the behavior of one group ofCallimico goeldiiin northwestern Bolivia. Data were collected for 1 year using focal animal sampling at 5‐min intervals, for a total of 1,375 observation hours. In total,C. goeldiiformed mixed species troops with five groups ofSaguinus fuscicollisand six groups ofS. labiatus, and these were maintained during 81% of observations.C. goeldiirested more and traveled less while alone than while associated, but neither vigilance behavior in the understory nor habitat use were affected by association status. The composition of the group's diet was different while alone (higher in structural carbohydrates [fungi] and lower in simple sugars [ripe fruits] and protein [insects]) than while associated (fungi 65 vs. 37%; fruits 13 vs. 32%; insects 5 vs. 15%). We propose therefore, thatC. goeldiihas a lower quality and more narrowly based diet while alone as compared to while associated. The factors that allow for this dietary expansion while in mixed species troops require further investigation. Am. J. Primatol. 69:1340–1353, 2007. © 2007 Wiley‐Liss, Inc.
Habituation of western gorillas: the process and factors that influence it
Authors: Doran‐Sheehy Diane M. , Derby Abigail M. , Greer David , Mongo Patrice
Published: May 2007

Habituation of western gorillas to human presence is generally an expensive, lengthy and difficult process. Here we describe the habituation process for two groups of western gorillas at the Mondika Research Center, with the hope that the lessons we learned will facilitate future gorilla studies. We expand upon earlier studies by describing the process through complete habituation for both males and females, and for more than one group. The major obstacle to habituation was developing sufficient tracking skills to follow gorilla trail on a daily basis. Once this was achieved, the silverback became semi‐habituated (i.e. ignoring human presence during half of contacts) within a year, although the majority of group females continued to avoid humans. As female presence at contacts increased, a period of male recidivism followed, requiring an additional year before his complete habituation was reached. Habituating the females took longer than the male, but we found, contrary to earlier studies, that it consisted of the same stages, including avoidance, aggression, and curiosity before habituation. We compare results between groups and across sites and discuss how factors such as tracking abilities, group size and cohesion, population density and home range overlap, and the manner of approaching gorillas during contacts influence the habituation process. Am. J. Primatol. 69:1354–1369, 2007. © 2007 Wiley‐Liss, Inc.
The effect of pulsed electromagnetic fields on secondary skin wound healing: An experimental study
Authors: Athanasiou Athanasios , Karkambounas Spiridon , Batistatou Anna , Lykoudis Efstathios , Katsaraki Afroditi , Kartsiouni Theodora , Papalois Apostolos , Evangelou Angelos
Published: May 2007

A variety of pulsed electromagnetic fields (PEMFs) have already been experimentally used, in an effort to promote wound healing. The aim of the present study was to investigate the effects of short duration PEMF on secondary healing of full thickness skin wounds in a rat model. Full thickness skin wounds, 2 by 2 cm, were surgically inflicted in two groups of male Wistar rats, 24 animals each. In the first group (experimental group ‐ EG), the animals were placed and immobilized in a special constructed cage. Then the animals were exposed to a short duration PEMF for 20 min daily. In the second group (control group ‐ CG), the animals were also placed and immobilized in the same cage for the same time, but not exposed to PEMF. On days 3, 6, 9, 12, 18, and 22, following the infliction of skin wounds, the size and healing progress of each wound were recorded and evaluated by means of planimetry and histological examination. According to our findings with the planimetry, there was a statistically significant acceleration of the healing rate for the first 9 days in EG, whereas a qualitative improvement of healing progress was identified by histological examination at all time points, compared to the control group. Bioelectromagnetics 28:362–368, 2007. © 2007 Wiley‐Liss, Inc.
Lack of promotion of mammary, lung and skin tumorigenesis by 20 kHz triangular magnetic fields
Authors: Lee Hae‐June , Choi Soo‐Yong , Jang Ja‐June , Gimm Youn‐Myoung , Pack Jeong‐Ki , Choi Hyung‐Do , Kim Nam , Lee Yun‐Sil
Published: May 2007

In order to evaluate possible tumorigenic effects of a 20 kHz intermediate frequency triangular magnetic field (IF), a frequency emitted from TV and PC monitors at 6.25 µT rms, which is the regulated exposure limit of magnetic field for the public in Korea, mammary tumors were produced in female Sprague–Dawley rats by oral intubation of dimethylbenz(a)anthracene (DMBA), lung tumors in ICR mice by scapular region injection of benzo(a)pyrene (BP), and skin tumors in female ICR mice by topical application of DMBA and tetradecanoylphorbolester (TPA). IF was applied 8 h/day for 14 weeks beginning the day after DMBA treatment for mammary tumor experiment, for 6 weeks after weaning for lung tumor, and for 20 weeks beginning 1 week after DMBA application for skin tumor experiment. For skin tumors, TPA was applied once a week for 19 weeks. Results showed no significant differences in tumor incidence, mean tumor number and volume, and histological patterns between IF magnetic‐field exposed and sham control rats in the above three tumor models. Therefore, we conclude that within the limitation or number of animals and the experimental conditions, 20 kHz IF triangular magnetic field exposure of 6.25 µT does not appear to be a strong co‐tumorigenic agent in the chosen murine mammary, lung and skin models. Bioelectromagnetics 28:446–453, 2007. © 2007 Wiley‐Liss, Inc.
The effect of GSM and TETRA mobile handset signals on blood pressure, catechol levels and heart rate variability
Authors: Barker Anthony T. , Jackson Peter R. , Parry Helen , Coulton Leslie A. , Cook Greg G. , Wood Steven M.
Published: May 2007

An acute rise in blood pressure has been reported in normal volunteers during exposure to signals from a mobile phone handset. To investigate this finding further we carried out a double blind study in 120 healthy volunteers (43 men, 77 women) in whom we measured mean arterial pressure (MAP) during each of six exposure sessions. At each session subjects were exposed to one of six different radio frequency signals simulating both GSM and TETRA handsets in different transmission modes. Blood catechols before and after exposure, heart rate variability during exposure, and post exposure 24 h ambulatory blood pressure were also studied. Despite having the power to detect changes in MAP of less than 1 mmHg none of our measurements showed any effect which we could attribute to radio frequency exposure. We found a single statistically significant decrease of 0.7 mmHg (95% CI 0.3–1.2 mmHg, P = .04) with exposure to GSM handsets in sham mode. This may be due to a slight increase in operating temperature of the handsets when in this mode. Hence our results have not confirmed the original findings of an acute rise in blood pressure due to exposure to mobile phone handset signals. In light of this negative finding from a large study, coupled with two smaller GSM studies which have also proved negative, we are of the view that further studies of acute changes in blood pressure due to GSM and TETRA handsets are not required. Bioelectromagnetics 28:433–438, 2007. © 2007 Wiley‐Liss, Inc.
One Parameter Model for Three‐Factor Interactions in Contingency Tables
Authors: Ama Njoku O.
Published: May 2007

This paper shows that the sum of products models for three and higher order interactions in contingency tables can be reparameterized in the spirit of TUKEY (1949) to yield chi‐square tests with one degree of freedom. The merits of this new test over the other known tests for the same hypotheses are discussed.
On the Estimation of Relative Risks and Longevities of a Class of Cancer Patients Based on Randomly Censored Data
Authors: Biswas Suddhendu , Jha Shishir Kumar
Published: May 2007

An attempt has been made to measure the relative risks and longevities of a group of cancer patients using a Weibull model whose parameters are function of covariatcs (viz treatment and condition of the patient). The methodology is Cox's Partial Likelihood and the Maximum Likelihood techniques for randomly censored data. The data consists of the records of 134 patients under a clinical trial in the treatment of Carcinoma of the Oro Pharynx as quoted by Kalbfleisch and Prentice (1980).
The Probability of a Negative Linear Combination of Independent Mean Squares
Authors: Khuri Andrea I.
Published: May 2007

SATTERTHWAITE'S (1941) approximation of the distribution of a linear combination, of independent mean squares is a commonly used technique in the analysis of variance. Confidence intervals and test statistics based on this approximation require that be positive. In this article, the probability that will be negative is considered in situations in which the mean squares are associated with a general balanced mixed model. Expressions are given for exact and approximate values of this probability in terms of the expected values and degrees of freedom of the mean squares. An example is presented to illustrate the implementation of the proposed methodology.
Test of Independence Against a Class of Ordered Alternatives in an R × C Contingency Table
Authors: Oluyede Broderick O.
Published: May 2007

Test procedures are developed for testing the hypotheses of independence in a two‐way contingency table against a class of ordered alternatives defined in terms of pooled crossproduct ratios. The alternatives hypotheses of “positive dependence” defines new notions of dependence. The distribution of the test statistics is obtained. Admissibility of the test is deduced and power comparison with some known test procedures are given. A numerical example is presented to illustrate the techniques developed.
Weighted Diallel Analysis Across Environments: Combining Ability and Heterotic Pattern Models
Authors: Hohls T. , Clarke G. P. Y. , Gevers H. O.
Published: May 2007

The matrix algebra needed for analysing data from diallel experiments across several environments is provided. Practical considerations for subdividing large incidence matrices and appending constraint matrices are discussed to allow large experiments to be analysed on desk top computers. In particular, a combining ability model and heterotic pattern model have been used to show how heterogeneous variances can be accommodated by weighting. The models provide valuable information on the performance of lines in crosses, the heterotic patterns of the lines, and the heterotic groups to which they belong. The methodology is illustrated by application to a diallel cross conducted among 12 elite white modified opaque‐2 maize inbred lines.