Showing papers in "Angle Orthodontist in 2005"
TL;DR: The results showed that RME produced a significant increase in all measured transverse linear dimensions, decreasing in magnitude from dental arch to basal bone, and the tooth tissue-borne expander produced a greater change in the axial inclination of appliance-supporting teeth, especially first premolars, compared with the tooth-borneexpander.
Abstract: This study evaluated rapid maxillary expansion (RME) dentoskeletal effects by means of computed tomography (CT), comparing tooth tissue-borne and tooth-borne expanders. The sample comprised eight girls aged 11 to 14 years presenting Class I or II malocclusions with posterior unilateral or bilateral crossbite that were randomly divided into two treatment groups, palatal acrylic (Haas-type) and hygienic (Hyrax) expanders. All appliances were activated up to the full seven mm capacity of the expansion screw. The patients were subjected to a spiral CT scan before expansion and after a three-month retention period when the expander was removed. One-millimeter-thick axial sections were scanned parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure maxillary transverse dimensions and posterior teeth inclination by means of a computerized method. The results showed that RME produced a significant increase in all measured transverse linear dimensions, decreasing in magnitude from dental arch to basal bone. The transverse increase at the level of the nasal floor corresponded to one-third of the amount of screw activation. Tooth-borne (Hyrax) and tooth tissue-borne (Haas-type) expanders tended to produce similar orthopedic effects. In both methods, RME led to buccal movement of the maxillary posterior teeth, by tipping and bodily translation. The second premolars displayed more buccal tipping than the appliance-supporting teeth. The tooth tissue-borne expander produced a greater change in the axial inclination of appliance-supporting teeth, especially first premolars, compared with the tooth-borne expander.
257 citations
TL;DR: In this paper, a systematic review was conducted to evaluate long-term transverse, anteroposterior and vertical skeletal changes after rapid maxillary expansion (RME), and the data were clinical trials that assessed skeletal changes through cephalometric analysis.
Abstract: The objective was to evaluate long-term transverse, anteroposterior and vertical skeletal changes after rapid maxillary expansion (RME). The data were clinical trials that assessed skeletal changes through cephalometric analysis. No surgical or other simultaneous treatment during the evaluation period was accepted. Electronic databases (PubMed, Medline, Medline In-Process & Other Non-Indexed Citations, Cochrane Database of Systematic Reviews, ASP Journal Club, DARE, CCTR, Embase, Web of Sciences and Lilacs) were searched with the help of a senior Health Sciences librarian. Abstracts that appeared to fulfill the initial selection criteria were selected by consensus. The original articles were then retrieved. A methodological checklist was used to evaluate the quality of the selected articles. Their references were also hand-searched for possible missing articles. Articles without an adequate control group to factor out growth changes were excluded. Only three articles (one measuring transverse and two anteroposterior and vertical changes) measured RME stability after active expansion, all of them had some methodological flaws, which limit the attainable conclusions. An individual analysis of these articles was made. Long-term transverse skeletal maxillary increase is approximately 25% of the total dental expansion for prepubertal adolescents. Better long-term outcomes are expected in transverse changes because of RME in less skeletally mature patients. RME appears not to produce clinically significant anteroposterior or vertical changes in the position of the maxilla and mandible. The conclusions from this systematic review should be considered with caution because only a secondary level of evidence was found. Long-term randomized clinical trials are needed.
176 citations
TL;DR: It can be concluded that intrusion of teeth causes about four times more root resorption than extrusion in the same individual after application of continuous intrusive and extrusive forces.
Abstract: The aim of this investigation was to compare root resorption in the same individual after application of continuous intrusive and extrusive forces. In nine patients (mean age 15.3 years), the maxillary first premolars were randomly intruded or extruded with a continuous force of 100 cN for eight weeks. Eleven maxillary first premolars from six randomly selected orthodontic patients served as controls. Root resorption was determined using scanning electron microscopy. Quantitative assessment of the percentage of resorbed area of the total root surface was performed on composite micrographs. The severity of root resorption was also assessed by visual scoring of the roots. Root resorption mainly occurred at the apical part of the roots in both experimental groups. A significant difference in root resorption was found between the intruded and the control teeth (P = .006) but not between the extruded and the control teeth. However, the mesial and distal root surfaces showed resorption on 5.78 +/- 3.86% of the root surface of the intruded teeth and 1.28 +/- 1.24% of the root surface of the extruded teeth, and this difference was significant (P = .004). In addition, a large individual variation was found. From this study, it can be concluded that intrusion of teeth causes about four times more root resorption than extrusion. Because the amount of root resorption due to intrusion or extrusion in the same patient is correlated, every clinician should be aware that the extrusion of teeth might also cause root resorption in susceptible patients.
151 citations
TL;DR: A significant overall gain in the maxillary and mandibular arch perimeter was found in adolescents and young adults, and more transverse dental arch changes were found after puberty as compared with before, but the difference may not be clinically significant.
Abstract: This systematic review evaluates long-term dental arch changes after rapid maxillary expansion treatment on orthodontic patients with constricted arches. Clinical trials that assessed dental arch changes through measurements on dental casts or cephalometric radiographs were selected. No patients with surgical or other simultaneous treatment during the active expansion period were accepted. Electronic databases were searched with the help of a senior Health Sciences librarian. Original articles were retrieved from the selected abstracts, and their references were also scanned for possible missing articles. Forty-one articles met the initial inclusion criteria, but 35 were later rejected because they lacked a control group or only evaluated dental changes or used a semirapid technique. Some of them also lacked a reported measurement error. From the remaining articles, two did not report a long-term evaluation. From the final four articles, two measured changes through dental casts and two assessed changes through radiographs (one through lateral cephalometric radiographs and one through posteroanterior radiographs). Similar maxillary molar and cuspid expansion could be found in adolescents and young adults. Significantly less indirect mandibular molar and cuspid expansion was attained in young adults compared with adolescents. A significant overall gain in the maxillary and mandibular arch perimeter was found in adolescents. More transverse dental arch changes were found after puberty as compared with before, but the difference may not be clinically significant. No anteroposterior dental changes were found on lateral cephalometric radiographs.
135 citations
TL;DR: In the tooth impaction cases, the CT images provided more precise information than conventional radiographic images such as improved observation of the long axis of the tooth, root condition, and overlap with bone.
Abstract: Considerable progress has been made in diagnostic, medical imaging devices such as computed tomography (CT). However, these devices are not used routinely in dentistry and orthodontics because of high cost, large space requirements and the high amount of radiation involved. A device using computed tomography technology has been developed for dental use called a limited cone beam dental compact-CT (3DX). The aim of this article is to demonstrate the usefulness of 3DX imaging for orthodontic diagnosis and treatment planning. We present three cases: (1) one case shows delayed eruption of the upper left second premolar, (2) the second case shows severe impaction of a maxillary second bicuspid; and (3) the third case shows temporomandibular joint disorder (TMD). In the tooth impaction cases, the CT images provided more precise information than conventional radiographic images such as improved observation of the long axis of the tooth, root condition, and overlap with bone. In the TMD case, clear and detailed temporomandibular joint images were observed and pre- and posttreatment condylar positions were easily compared. We conclude that 3DX images provide useful information for orthodontic diagnosis and treatment planning.
130 citations
TL;DR: The use of a lever-arm and mini-implant system as absolute anchorage for controlled retraction of the anterior teeth during lingual orthodontic treatment is described and 2 protrusion cases treated with this system are evaluated.
Abstract: Anterior torque control during retraction is difficult to achieve with lingual orthodontic treatment. This article describes the use of a lever-arm and mini-implant system as absolute anchorage for controlled retraction of the anterior teeth during lingual orthodontic treatment and evaluates 2 protrusion cases treated with this system. Various clinical situations are discussed and analyzed from a biomechanical standpoint. Mini-implants are needed to control the point of force application in the posterior area and produce en masse retraction with no anchorage loss. When the length of the lever-arm is adjusted to the position of the mini-implant, the desired line of action of the retraction force with respect to the center of resistance of the anterior segment is selected. Controlled retraction of the anterior teeth was achieved with no loss of anchorage. The mini-implant, in conjunction with the lever-arm, is useful not only for absolute anchorage but also for anterior torque control during retraction in lingual orthodontic treatment.
104 citations
TL;DR: All malocclusion groups showed statistically significant higher overall ratios than the normal occlusion group (P < .001); however, there were a large number of patients within each group who had discrepancies greater than 2 SD from the mean.
Abstract: The aims of this study were to identify the possible sex differences in tooth size ratios between males and females, to determine whether there is a difference in the incidence of tooth size discrepancies for both the anterior and overall ratios when comparing with Angle Class I; Class II, division 1; Class II, division 2; and Class III malocclusion groups, to compare the tooth size ratios of different malocclusion groups with the anterior and overall tooth size ratios of 150 untreated normal occlusion subjects. In addition, the aim was to determine the percentage of tooth size discrepancies outside 2 SD from Bolton means for tooth ratios present in each malocclusion group and in the overall sample of this study. This study consisted of 150 subjects who served as the normal occlusion group and 560 patients who showed four different malocclusion characteristics (Angle Class I; Class II, division 1; Class II, division 2; and Class III). Tooth size measurements were performed on the models of normal occlusion and pretreatment models. For statistical evaluation, Student's t-test, analysis of variance and Tukey Honestly Significant Difference tests were performed. A significant sex difference was found only in the overall ratio for normal occlusion subjects (P < .001). All malocclusion groups showed statistically significant higher overall ratios than the normal occlusion group (P < .001). There were no statistically significant differences among malocclusion groups; however, there were a large number of patients within each group who had discrepancies greater than 2 SD from the mean. Further investigations are needed to explain the probable racial differences and relationships between malocclusion and tooth size measurements.
102 citations
TL;DR: Orthodontic patients with detectable root resorption during the first six months of active treatment are more likely to experience resOrption in the following six-month period than those without.
Abstract: The low explained variance of identified risk factors for apical root resorption in or- thodontic patients suggests effects of parameters related to individual predisposition. Our purpose was to explore this hypothesis. We evaluated standardized periapical radiographs of the maxillary incisors made before treatment (T1) as well as at about six and 12 months after bracket placement (T2 and T3) of 247 patients aged 10.1 to 57.1 years at T1. The radiographs were converted to digital images, and commercially available software was used to correct for differences in projec- tion. The results showed that 20.2%, 7.7%, and 5.3% of the patients had $1 tooth with .2.0, 3.0, and 4.0 mm resorption at T3, respectively. Pearson's correlation revealed an association between resorption from T1 to T2 and from T2 to T3 (P , .01). The risk of $1 tooth with .1.0 mm resorption from T2 to T3 was 3.8 times higher (95% CI 2.4-6.0) in patients with $1 tooth with .1.0 mm from T1 to T2 than in those without. Also, resorption was more pronounced (P , .001) from T2 to T3 in patients with $1 tooth with .1.0 mm and .2.0 resorption from T1 to T2 than in those without. The explained variance of identified risk factors was,10%. Orthodontic patients with detectable root resorption during the first six months of active treatment are more likely to experience resorption in the following six-month period than those without. (Angle Orthod 2005;75:919-926.)
99 citations
TL;DR: Findings appear to indicate the greater likelihood of sella turcica bridging and abnormal sella Turcica dimensions in subjects treated by combined surgical-orthodontic means rather than by orthodontics only.
Abstract: The aim of the study was to compare the incidence of sella turcica bridging and sella turcica dimensions in 150 Caucasian subjects who had combined surgical-orthodontic correction of their malocclusion with a randomly selected group of 150 Caucasian subjects who were treated contemporaneously by orthodontic means only. Pretreatment lateral cephalometric radiographs were scanned and analyzed. A sella turcica bridge was identified as a continuous band of bony tissue extending from the anterior cranial fossa to the posterior cranial fossa. The dimensions of the sella turcica were measured. In the group treated by combined surgical-orthodontic means, the incidence of bridging was 16.7%, whereas it was 7.3% in the orthodontics-only group (P = .012). Significant increases in the mean surface area (P = .02) and mean perimeter of the sella turcica (P = .01) were found for the combined surgical-orthodontic group compared with the orthodontics-only group. The mean interclinoid distance was significantly smaller in the surgical-orthodontic group (P = .02). These findings appear to indicate the greater likelihood of sella turcica bridging and abnormal sella turcica dimensions in subjects treated by combined surgical-orthodontic means rather than by orthodontics only.
95 citations
TL;DR: The combination of the sums of permanent upper and lower central incisors and upper first molars was the best predictor for the SPCP in this sample, including sex and arch as additional predictor variables.
Abstract: The lower permanent incisor tooth width sum has been proposed as the best predictor for the tooth width sums of the unerupted canine and premolars (SPCP) for populations from different ethnic origins. Only two previous studies have refuted it. The purpose of the present study was to determine which sum or combination of sums of permanent tooth widths presented the best prediction capability for the SPCP in a Peruvian sample, to calculate a specific linear regression equation for this population, and to evaluate the clinical significance. A total of 150 children with complete permanent dentitions were selected. Fifty more children were used as a validation sample for the application of a multiple linear regression equation (MLRE). They did not present clinically visible dental caries or proximal restorations and no active or previous orthodontic treatment. Their dental casts were measured to 0.1 mm with a sliding caliper with a Vernier scale. Three-way analysis of variance, Pearson Correlation Test, Fisher Z values and a MLRE were used for the statistical analysis. The combination of the sums of permanent upper and lower central incisors and upper first molars was the best predictor for the SPCP in this sample. A MLRE was calculated including sex and arch as additional predictor variables. The MLRE determination coefficient was 60% with a standard error of 0.8 mm. This new MLRE underestimates (less than 1 mm discrepancy) the actual SPCP in only 7% of the cases on the basis of a validation sample.
93 citations
TL;DR: Comparing the transverse dimensions of the dental arches and alveolar arches in the canine, premolar, and molar regions of Class II division 1 and Class IIdivision 2 malocclusion groups with normal occlusion subjects indicates that rapid maxillary expansion rather than slow expansion may be considered before or during the treatment of Class I division 1 patients.
Abstract: The aim of this study was to compare the transverse dimensions of the dental arches and alveolar arches in the canine, premolar, and molar regions of Class II division 1 and Class II division 2 malocclusion groups with normal occlusion subjects. This study was performed using measurements on dental casts of 150 normal occlusion (mean age: 21.6 +/- 2.6 years), 106 Class II division 1 (mean age: 17.2 +/- 2.4 years), and 108 Class II division 2 (mean age: 18.5 +/- 2.9 years) malocclusion subjects. Independent-samples t-test was applied for comparisons of the groups. These findings indicate that the maxillary interpremolar width, maxillary canine, premolar and molar alveolar widths, and mandibular premolar and molar alveolar widths were significantly narrower in subjects with Class II division 1 malocclusion than in the normal occlusion sample. The maxillary interpremolar width, canine and premolar alveolar widths, and all mandibular alveolar widths were significantly narrower in the Class II division 2 group than in the normal occlusion sample. The mandibular intercanine and interpremolar widths were narrower and the maxillary intermolar width measurement was larger in the Class II division 2 subjects when compared with the Class II division 1 subjects. Maxillary molar teeth in subjects with Class II division 1 malocclusions tend to incline to the buccal to compensate the insufficient alveolar base. For that reason, rapid maxillary expansion rather than slow expansion may be considered before or during the treatment of Class II division 1 patients.
TL;DR: The findings suggest that the use of an in vitro testing model that includes 10 brackets can give additional interesting information about the frictional force of the various bracket-archwires combinations to the clinician and the research worker.
Abstract: The friction generated by various bracket-archwire combinations previously has been studied using in vitro testing models that included only one or three brackets This study was performed using a specially designed apparatus that included 10 aligned brackets to compare the frictional resistance generated by conventional stainless steel brackets, self-ligating Damon SL II brackets and Time Plus brackets coupled with stainless steel, nickel-titanium and beta-titanium archwires All brackets had a 0022-inch slot, and five different sizes of orthodontic wire alloys used Each bracket-archwire combination was tested 10 times, and each test was performed with a new bracket-wire sample Time Plus self-ligating brackets generated significantly lower friction than both the Damon SL II self-ligating brackets and Victory brackets However, the analysis of the various bracket-archwire combinations showed that Damon SL II brackets generated significantly lower friction than the other brackets when tested with round wires and significantly higher friction than Time Plus when tested with rectangular archwires Beta-titanium archwires generated higher frictional resistances than the other archwires All brackets showed higher frictional forces as the wire size increased These findings suggest that the use of an in vitro testing model that includes 10 brackets can give additional interesting information about the frictional force of the various bracket-archwires combinations to the clinician and the research worker
TL;DR: The results revealed that, in late-adolescent patients, the Jasper Jumper corrected Class II discrepancies mostly through dentoalveolar changes, and it is suggested that this treatment method could be an alternative to orthognathic surgery in borderline Class II cases.
Abstract: The purpose of this study was to evaluate the skeletal, dental, and soft-tissue changes in late-adolescent patients treated with Jasper Jumpers applied with sectional arches. The study sample consisted of 30 subjects (15 treated, 15 untreated) with skeletal and dental Class II malocclusion. Our study was carried out on 75 lateral cephalometric films. Among these radiograms, 15 were taken before the leveling stage in the treatment group. Half of the remaining 60 were taken before placement and after removal of the Jasper Jumper appliance in the treatment group and the other half at the beginning and six months after in the control group. The patient selection criteria were Class II malocclusion caused by retrognathic mandible, normal or low-angle growth pattern, and postpeak growth period. The statistical assessment of the data suggests that the sagittal growth potential of the maxilla was inhibited. There were no significant changes in the vertical skeletal parameters. The mandibular incisors were protruded and intruded, whereas the maxillary incisors were retruded and extruded. The upper molars tipped distally as the lower molars tipped mesially. Because of these changes, the occlusal plane rotated in the clockwise direction. Overbite and overjet were reduced, and the soft-tissue profile improved significantly. The results revealed that, in late-adolescent patients, the Jasper Jumper corrected Class II discrepancies mostly through dentoalveolar changes. It is suggested that this treatment method could be an alternative to orthognathic surgery in borderline Class II cases.
TL;DR: RME is capable of increasing nasopharyngeal airway adequacy in girls, and this leads to a decrease in craniocervical angulations, and the clinical importance of these results is yet to be clarified.
Abstract: The influence of respiratory function on craniofacial development and head posture has been demonstrated previously. This study evaluated the effect of rapid maxillary expansion (RME) on nasopharyngeal airway adequacy, head posture, and facial morphology in children with nasal obstruction. Fifty-five girls (8-15 years of age) who needed maxillary expansion, showed reduced nasopharyngeal airway adequacy (pm-Ad 2), and were subjectively assessed as mouth breathers were allocated randomly into 2 groups. The 23 subjects in the first group were treated with RME, and the 22 subjects in the other group were followed about 8 months before beginning therapy and became untreated controls. Dental casts and lateral skull radiographs exposed in natural head position were obtained at the first visit and 6 months later for all subjects. In the girls under active treatment there was a statistically significant increase of pm-Ad 2 (P < .0001), a significant increase of the cervical lordosis angle (P < .0001), a flexion of the head (P < .0001), and a decrease in the craniocervical angulation (P < .0001) (paired t-tests). No significant changes were seen in the control group. The correlation coefficients indicated a mild correlation between pm-Ad 2 distance and craniocervical angulation (SN/OPT angle) (r = 0.61 at P < .001). RME is capable of increasing nasopharyngeal airway adequacy in girls, and this leads to a decrease in craniocervical angulations. The clinical importance of these results is yet to be clarified.
TL;DR: Onplants can be used as an extremely stable anchorage for maxillary orthopedic facemask treatment and a significant improvement in midface esthetics is noted, noted by an increase in fullness of the infraorbital region.
Abstract: A hexagonal onplant of 7.7 mm diameter was placed on the palatal bone of the maxilla in an 1-year five-month-old female patient with a Class III malocclusion and midface deficiency. Elastic traction (400 g per side) was applied from a facemask to the onplant at 30 degrees to the occlusal plane 12 hours per day for 12 months. The maxilla was found to have displaced forward and downward by 2.9 mm. The mandible was rotated downward and backward. There was a 3 degrees increase in mandibular plane angle and an increase in the lower face height. Clinically, there was a significant improvement in midface esthetics, noted by an increase in fullness of the infraorbital region and correction of the skeletal discrepancy between the maxillary and mandibular jaw relationship. Contrary to the reports that use teeth rather than onplants as anchorage, there was no forward movement of the maxillary molars and minimal extrusion of the maxillary molars. These results suggest that onplants can be used as an extremely stable anchorage for maxillary orthopedic facemask treatment.
TL;DR: The hypothesis that P2 extraction in hyperdivergent facial types will result in mesial molar movement and decrease FVD by reducing the wedge effect is invalid because there is no decrease in FVD regardless of the maxillary and mandibular P1 or P2 extractions.
Abstract: If the concept of mesial movement of molars to reduce the ''wedge effect'' and decrease facial vertical dimension (FVD) is valid, it is important to investigate the effect of first (P1) and second premolar (P2) extraction on FVD. This study compares the mesial movement of molars and changes in FVD between P1 and P2 extraction groups in Class I malocclusion with a hyperdivergent facial type. We compared 27 cases with maxillary and mandibular P1 extractions (group 1) and 27 cases with maxillary and mandibular P2 extractions (group 2). To determine FVD changes due to treatment and to compare differences between two groups, paired t-test and independent t-test were performed, respectively. Group 2 showed more mesial movement of the maxillary and mandibular first molars and less retraction of the maxillary and mandibular central incisors than group 1 (P , .05). Both groups showed increased anterior facial height (P , .05), but there were no statistically significant differences in angular and proportional measurements between pre- and posttreatment. There was no significant difference in the amount of FVD change between groups 1 and 2 except in the maxillomandibular plane angle and SN to palatal plane angle (P , .05). These results suggest that there is no decrease in FVD regardless of the maxillary and man- dibular P1 or P2 extraction. Therefore, the hypothesis that P2 extraction in hyperdivergent facial types will result in mesial molar movement and decrease FVD by reducing the wedge effect is invalid. (Angle Orthod 2005;75:177-182.)
TL;DR: It is concluded that local host response toward the orthodontic forces might lead an increase in IL-8 and neutrophil accumulation, and this may be one of the triggers for bone remodeling processes.
Abstract: A host-derived neutrophil-activating cytokine interleukin-8 (IL-8) is secreted mainly by monocytes and is considered to be important in regulating alveolar bone resorption during tooth movement. The aim of this study was to evaluate the levels of IL-8 during mechanical forces on periodontal tissues at different stages of orthodontic therapy. Ten canine teeth of patients having different Angle classifications were selected for the study. After the premolars were extracted, the maxillary/mandibular canines were tipped distally. Gingival crevicular fluid was sampled from mesial and distal gingival crevices of each canine separately at baseline and one hour, 24 hours, six days, 10 days, and 30 days after the application of the force. An enzyme-linked immunosorbent assay for quantitative detection of IL-8 was used. Although there was an increase in the concentration of IL-8 at tension (mesial) sites after one hour, 24 hours, six days, and 10 days, a decrease was observed at 30 days. Pressure (distal) sites did not demonstrate such an increase at any period except at 10 days. However, the concentration of IL-8 at both sites showed a similar decrease and approached each other at day 30. We concluded that local host response toward the orthodontic forces might lead an increase in IL-8 and neutrophil accumulation, and this may be one of the triggers for bone remodeling processes.
TL;DR: There is a general trend of increase in the ossification of laryngeal cartilages as the age advanced, and thyroid cartilage was more frequently ossified compared with cricoid.
Abstract: This study was undertaken to identify the variations in the physiologic ossification of human laryngeal cartilages by evaluating the lateral cephalometric radiographs of healthy males and females referred to our facility. Lateral cephalometric radiographs of 359 patients (141 male and 218 female; ages 10 to 59 years) referred from various specialty clinics between April 1998 and March 2000 were used. Frequencies and confidence intervals were obtained and tabulated for both thyroid and cricoid ossifications as seen on these cephalometric radiographs. The interobserver agreement was strong for both thyroid (kappa = .986) and cricoid (kappa = .982) observations. Overall, thyroid cartilage was more frequently ossified compared with cricoid. Various degrees of thyroid and cricoid cartilage ossification were found in 186 patients (120 female and 66 male) in the third decade and beyond. Among 173 patients in the first 2 decades (98 females and 75 male), evidence of thyroid ossification was found in 2 male patients aged 14 and 18, and ossification was detected in the cricoid cartilage in 12 patients. There was a preponderance of laryngeal cartilage ossification in men compared with women. Radiographically detectable laryngeal ossification increased with age starting in the third decade. There is a general trend of increase in the ossification of laryngeal cartilages as the age advanced.
TL;DR: Results suggest that occlusal stimuli promoted the regeneration of the PDL and prevented dentoalveolar ankylosis, whereas excessive initial force might cause severe root and bone resorption.
Abstract: The process of healing periodontal ligaments (PDL) after transplantation has been widely examined, but the mechanism for preventing dentoalveolar ankylosis is still unclear. In this study, we focused on the role of mechanical stimuli in preventing ankylosis using an animal model of tooth transplantation assessed by histologic observation and evaluation of proliferating PDL cells. Five-week-old Sprague-Dawley male rats were divided into occluded and nonoccluded groups. The right maxillary first molars were replanted in both groups, and histologic observations were carried out after one or two weeks. The proliferative activity of PDL cells was also examined by assessing the distribution of 5-bromo-2'-deoxyuridine (BrdU). After two weeks in the nonoccluded group, ankylosis was clearly detected and PDL stricture was obvious, whereas no severe bone or root resorption was observed. On the other hand, the occluded group showed an enlarged and thickened PDL with extensive root resorption, but no ankylosis. Based on these findings, the replanted teeth were given a one-week healing period and then occlusion recovery was assessed, which resulted in decreased ankylosis and root resorption. The proliferative activity of PDL cells in the occluded group was generally higher than in the nonoccluded group. The activity of PDL cells in the recovery group was also higher than that of the nonoccluded group. These results suggest that occlusal stimuli promoted the regeneration of the PDL and prevented dentoalveolar ankylosis, whereas excessive initial force might cause severe root and bone resorption.
TL;DR: A new dental flowable composite, Denfil Flow, was evaluated for the bonding of orthodontic brackets by determining its shear bond strength (SBS) and the mode of bond failure after debonding, and a clinically acceptable SBS was found for the two adhesives.
Abstract: A new dental flowable composite, Denfil Flow, was evaluated for the bonding of orthodontic brackets by determining its shear bond strength (SBS) and the mode of bond failure after debonding. Eighty extracted human premolars were divided into two equal groups. Metal brackets were bonded to etched enamel using a composite resin control (Transbond XT) or Denfil Flow. After 72 hours of incubation in saline solution at 37°C, debonding was performed with a shearing force. The SBS and the mode of bond failure were examined. In addition, representative samples from each group were examined by scanning electron microscopy (SEM). No significant difference was observed in the SBS between the groups, and a clinically acceptable SBS was found for the two adhesives. Bond failures occurred mostly in the bracket–adhesive interface, without significant differences between the groups. At SEM analysis, Denfil Flow showed a greater frequency of air bubbles within the resin than did Transbond XT. In conclusion, Denfi...
TL;DR: The soft tissue changes after the extraction of maxillary first premolars and subsequent anterior tooth retraction were evaluated and labial and nasolabial angles tended to open after incisor retraction, but there was little predictability for this response.
Abstract: The soft tissue changes after the extraction of maxillary first premolars and subse- quent anterior tooth retraction were evaluated for 16 Class II, division 1 patients. Pre- and post- treatment lateral head cephalograms were evaluated using superimpositions on Bjork-type me- tallic implants in the maxilla. The patient sample was divided into group I patients, those who did exhibit lip seal at rest in the pretreatment cephalogram and group II patients, those who did not exhibit lip seal at rest in the pretreatment cephalogram. Upper incisor retraction was followed by a similar ratio of upper lip retraction in both the lip seal and nonsealed groups (1:0.75 and 1:0.70 mean ratios, respectively). However, those without lip seal did demonstrate more retraction at stomion (USt). The final upper lip position (Ls) was reasonably correlated with retraction of the cervical maxillary incisor point (cU1) with determination coefficients of 63.6% in the lip sealed and 68.5% in the lip incompetent groups. Although labial and nasolabial angles tended to open after incisor retraction, there was little predictability for this response. (Angle Orthod 2005;75:499-505.)
TL;DR: The opinion that orthodontic treatment in childhood does not entail an increased risk to develop either signs or symptoms of TMD later in life is supported.
Abstract: This investigation analyzed the influence of orthodontic treatment performed in childhood on the long-term development of signs and symptoms of temporomandibular disorders (TMDs). The original sample consisted of 50 consecutive patients (27 girls and 23 boys) with different morphological malocclusions, who were to receive orthodontic treatment. Their mean age at start of treatment was 12.9 years. Seventeen (range 15–18) years after completion of orthodontic treatment, 40 former patients (89% of the traced subjects) completed and returned a questionnaire, and 31 subjects (69% of the traced subjects) were also examined clinically. A great majority of the participants were pleased with the result of the orthodontic treatment. Relapses of morphological malocclusions were very uncommon. The prevalence of signs and symptoms of TMD was low both before and after the active phase of orthodontic treatment, as well as at the long-term follow-up after 15 to 18 years. The incidence per year of manifest TMD re...
TL;DR: On the basis of the equation generated by the multivariate statistical method, impaction of the maxillary canine for each new case at the age of 8 years can be predicted.
Abstract: The aim of this study was to identify a model of cephalometric variables for early diagnosis of the displacement of upper permanent canine and early prognosis of upper canine impaction. Posteroanterior (PA) cephalograms of 43 subjects (22 males and 21 females) with different types of malocclusions in the mixed dentition were analyzed at the time of first observation (mean age 8 years and 5 ± 9 months). All subjects were reevaluated at the mean age of 14.3 years. At this time the sample was divided into 2 groups according to the presence of canine impaction: nonimpacted canine group (31 subjects) and impacted canine group (12 subjects). Stepwise variable selection on the measurements at the time of first observation identified 2 predictive variables on PA cephalograms, ie, the distance between the center of the canine crown and the midsagittal plane (A3cc to Cg Vertical) and the distance between the jugal process and the midsagittal plane (J to Cg Vertical). The closer the canine crowns to the mid...
TL;DR: The variation in the dimensions of the elastomeric ligatures is able to influence the static frictional resistance generated by orthodontic sliding mechanics in the buccal segments and determines a 13-17% decrease in static friction compared with large ligatures.
Abstract: The aim of this study was to evaluate in vitro the effect of variations in the size of elastomeric ligatures on the static frictional resistance generated by orthodontic sliding mechanics under dry condition. Frictional forces generated by elastomeric ligatures treated with a lubricating material (silicone) were analyzed as well. An Instron testing machine was used to assess the static frictional forces of a 0.019 x 0.025-inch stainless steel rectangular wire that was ligated to a molar convertible tube and to three stainless steel 0.022-inch pre-adjusted brackets with elastomeric ligatures with different dimensions: small, medium, and large. The static friction produced by two prototypes of silicone-lubricated elastomeric ligatures was also measured. The small and medium elastomeric ligatures produced significantly less friction than the large ligatures. No statistically significant difference was found between small and medium ligatures. The decrease in frictional forces of small and medium modules had to be ascribed mainly to the smaller thickness of both ligatures with respect to large ligatures. The lubricated elastomeric ligatures generated significantly smaller frictional forces than nonlubricated elastomeric ligatures with different dimensions. The variation in the dimensions of the elastomeric ligatures is able to influence the static frictional resistance generated by orthodontic sliding mechanics in the buccal segments. The use of small and medium elastomeric ligatures determines a 13-17% decrease in static friction compared with large ligatures. Silicone-lubricated modules can reduce static friction by 23-34% with respect to the small and medium nonlubricated elastomeric ligatures and by 36-43% compared with nonlubricated large ligatures.
TL;DR: It can be concluded that none of the three mandibular anchorage forms used in Herbst treatment could prevent an anchorage loss.
Abstract: The aim of this study was to analyze the efficiency of the mandibular banded and cast splint anchorage forms used in Herbst treatment. The records of 16 Class II:1 subjects treated with mandibular banded premolar anchorage (group A), 19 Class II:1 subjects treated with mandibular banded premolar- molar anchorage (group B), 34 Class II:1 subjects (group C), and 18 Class II:2 subjects treated with mandibular cast splint anchorage (group D) were screened. The subjects in all four groups were treated for an average period of 0.6 years. Lateral head films were analyzed on four occasions ie, before treatment, after treatment, two years after, and four years after treatment. Mandibular anchorage loss during treatment was measured by the amount of anterior movement and proclination of the lower incisors as well as the anterior movement of the lower molars. During the treatment period a pronounced (P , .001) anchorage loss was found for all anchorage forms ie, incisor anterior movement/proclination as well as anterior movement of the lower molars. When comparing the cast splint anchorage in the Class II:1 and Class II: 2 cases, no difference was found with respect to the amount of mandibular anchorage loss of the incisors. After Herbst treatment, relapsing tooth movements were found in all three anchorage forms. It can be concluded that none of the three mandibular anchorage forms used in Herbst treatment could prevent an anchorage loss. Against all expectations, the cast splint anchorage was not better than the two banded anchorage forms. (Angle Orthod 2004;75:23-27.)
TL;DR: A systematic review of the literature to assess the scientific evidence on the actual outcome of early treatments of open-bite malocclusions is presented in this article, where a literature survey was done by applying the Medline database (Entrez PubMed).
Abstract: The aim of this study was a systematic review of the literature to assess the scientific evidence on the actual outcome of early treatments of open-bite malocclusions. A literature survey was done by applying the Medline database (Entrez PubMed). The survey covered the period from January 1966 to July 2004 and used the MeSH, Medical Subject Headings. The following study types that reported data on the treatment effects included: randomized clinical trials (RCT), prospective and retrospective studies with concurrent untreated as well as normal controls, and clinical trials comparing at least two treatment strategies without any untreated or normal control group involved. The search strategy resulted in 1049 articles. After selection according to the inclusionary/exclusionary criteria, seven articles qualified for the final review analysis. No RCTs of early treatment of anterior open bite have been performed. Two controlled clinical trials of early anterior open bite have been performed, and these two studies indicated the effectiveness of treatment in the mixed dentition with headgears or functional appliances (or both). Most of the studies had serious problems of lack of power because of small sample size, bias and confounding variables, lack of method error analysis, blinding in measurements, and deficient or lack of statis- tical methods. Thus, the quality level of the studies was not sufficient enough to draw any evi- dence-based conclusions. (Angle Orthod 2005;75:707-713.)
TL;DR: The Transb Bond XT conventionally bonded showed better adhesion results than Transbond XT, Z-100, and Concise Orthodontic after using Transbonding Plus Self-Etching Primer.
Abstract: The aim of this study was to determine the shear bond strength of different compos- ites and to determine the adhesive remnant index (ARI) of metallic brackets bonded to enamel prepared with Transbond Plus Self-Etching Primer (TPSEP). Forty human premolars were divided into four equal groups. In group 1 (control), the Transbond XT was conventionally used. In groups 2-4, the TPSEP was used before bonding with Transbond XT, Z-100, and Concise Orthodontic, respectively. After the bonding, the samples were stored in distilled water at 378C for 24 hours. The brackets were debonded using a universal testing machine at a crosshead speed of 0.5 mm/ min. The shear bond strength (MPa) for group 1 (control), group 2 (TPSEP 1 Transbond XT), group 3 (TPSEP 1 Z-100), and group 4 (TPSEP 1 Concise Orthodontic) were of 6.43, 4.61, 4.74, and 0.02, respectively. Group 1 was statistically superior to other groups (P , .05), but there was no statistically significant difference between groups 2 and 3 (P. .05), although both were sta- tistically superior to group 4 (P , .05). According to the ARI evaluation, most of the failures involved the bracket/composite interface (groups 1 and 2) as well as the enamel/composite in- terface (groups 3 and 4). The Transbond XT conventionally bonded showed better adhesion results than Transbond XT, Z-100, and Concise Orthodontic after using Transbond Plus Self- Etching Primer. (Angle Orthod 2005;75:849-853.)
TL;DR: The results raise the question of whether orthodontic treatment with similar appliances may have some, previously unsuspected, short- or long-term effects on the mandibular bone during growth and whether their effects depend on the individual soft-tissue characteristics.
Abstract: This study investigates the structural adaptation of the mandibular bone when subjected to different masticatory functional and mechanical demands during growth. The effect of two experimental factors, the insertion of a bite block and the alteration of food consistency, on the bone mineral density (BMD) of the mandible was investigated in growing rats. Fifty-two male albino rats were divided into two equal groups, fed with either the standard hard diet or soft diet, at the age of four weeks. After two weeks, half the animals in both groups had their upper molars fitted with an upper posterior bite block. The remaining animals served as a control. Region-specific BMD of the mandible was subsequently measured using dual-energy X-ray absorptiometry (DXA). Soft diet and the consequent reduction of the forces applied to the mandible during mastication resulted in the reduction of BMD in all regions under study. The insertion of the bite-opening appliance (bite block) and the resulting stretching of the soft tissues led to the application of a continuous light force on the lower molars, which was associated with a significant increase of the BMD in the part of the alveolar process just below the root apices. These results raise the question of whether orthodontic treatment with similar appliances may have some, previously unsuspected, short- or long-term effects on the mandibular bone during growth and whether their effects depend on the individual soft-tissue characteristics.
TL;DR: The distance of Me from the vertical reference line was the most relevant index for the subjective evaluation of facial asymmetry, and the influence of soft tissue structures should be considered in facial asymmetric.
Abstract: The purpose of this study was to investigate the relationship between the subjective evaluation of facial asymmetry and seven cephalometric indices. Ten orthodontists subjectively evaluated the frontal photographs of 100 subjects and categorized them into three categories, ie, category I--symmetrical view; category II--a little asymmetry not requiring treatment; and category III--marked asymmetry requiring treatment. Seven indices that were used to evaluate facial asymmetry were determined using frontal cephalographs of these patients. Interobserver agreement was assessed using Cohen's kappa statistic. Agreement among the observers for category III was higher than for categories I and II. To define the characteristics of each category, the cephalometric indices, which at least eight observers agreed on, were compared between the categories. No differences were found in any of the indices between categories I and II. Five indices showed differences between category III and the other categories. Among them, the distance of Me from the vertical reference line was the most relevant index for the subjective evaluation of facial asymmetry. When a discrepancy is found between skeletal measurements and a subjective evaluation, the influence of soft tissue structures should be considered in facial asymmetry.
TL;DR: Both acidic soft drink subgroups had a reduced debonding resistance in vivo and in vitro compared with their control subgroups and areas of defect due to erosion were observed on the enamel surface around the brackets in both the in vitro and in vivo groups.
Abstract: This study investigated the effects of acidic soft drinks on the resistance of metal brackets to shear forces in vitro and in vivo. Thirty noncarious maxillary premolar teeth, scheduled for extraction for orthodontic purposes, were used in the in vivo group. Thirty other noncarious maxillary premolar teeth, already extracted for orthodontic purposes, were used in the in vitro group. The teeth in both groups were divided equally in three subgroups, ie, the Coca-Cola, Sprite, and control subgroups. Brackets were bonded using conventional methods. Teeth in the in vivo group were rinsed with the acidic drink three times for five minutes daily and extracted after three months. Teeth in the in vitro group were kept in the acidic drink for five minutes on three equal time intervals within 24 hours. The brackets from both groups were subjected to shearing forces using a Universal test machine. After the shearing tests, a scanning electron microscope was used to determine the amount and the localization of erosion. The results indicated that both acidic soft drink subgroups had a reduced debonding resistance in vivo and in vitro compared with their control subgroups. No statistical difference in debonding resistance was found between the in vivo and in vitro groups. Areas of defect due to erosion were observed on the enamel surface around the brackets in both the in vitro and in vivo groups. Acidic soft drinks such as Coca-Cola and Sprite have a negative effect on bracket retention against shearing forces and enamel erosion.