American Journal of Orthodontics & Dentofacial Orthopedics

2010-02-01

Editor's Choice

David L. Turpin — 2010-02-01

Your favorite referring dentist has just seen a patient who completed treatment with you some time ago. You saved space in this patient for an implant to be placed for a missing maxillary lateral incisor, but the dentist says that there is not enough room between the adjacent roots. What happened? Did the roots of the adjacent teeth converge while the retainer was being worn, or were they not moved enough in the first place? This dilemma is frustrating for everyone involved.

Editors

2010-02-01

Information for readers

2010-02-01

Need and demand for orthodontic services: The final report

David L. Turpin — 2010-02-01

The Golden Age of orthodontics occurred in the 1950s and 1960s, when practitioners had more patients seeking care than they could start; some even had waiting lists as long as 6 months. Much has changed in the way treatment is delivered today, with the expanded use of well-trained auxiliary personnel and the availability of more efficient materials enhanced by technology. But do we have adequate data to determine who needs orthodontic treatment, and more importantly, are there enough orthodontists to get the job done? Some believe that there are not enough professionals to treat everyone in need, yet there are insufficient data to prove how many people in need would seek care even if it were available.

After 50 years in practice, the evidence is convincing

H.O. Blackwood — 2010-02-01

I have been in active orthodontic practice for nearly 50 years. During this time, I have seen many different theories for “orthodontic gnathology” and TMD diagnosis and treatment, with each guru espousing his own ideas of how things should be and what our goals should be. I wonder, with all this confusion, how practicing orthodontists have managed to do a fairly decent job for all these years. We have obviously been doing something right.

Gnathology lessons from a 1969 Oldsmobile engine

Stephen C. Roehm — 2010-02-01

In 1972, my father and I had our heads under the open hood of a 1969 Oldsmobile 442, listening to an idling 500-horsepower 455-cubic inch engine clunk and clatter. We both speculated as to the problem, and, after the tear-down the micrometer showed an extremely worn crankshaft. The noise from the engine of this muscle car was caused by the piston connecting rod slop and the piston hitting the head/valve at the top of the stroke cycle. The engine was out of centric relationship. The piston could travel past its terminal border position; parts were colliding, and eventually the system broke down.

Authors' response

Donald J. Rinchuse, Sanjivan Kandasamy — 2010-02-01

We thank Dr Roehm for his interest in our article. He provided a witty anecdote. Nonetheless, his comments are more theatrical than substantive. He furnished no research or evidence supporting his viewpoint, and his opinion typifies an experience-based (vs an evidence-based) view on the subject. Over the years, we have received numerous letters from orthodontists who have at one time subscribed to the tenets of gnathology but have since abandoned the philosophy, and they have the very opposite experience to Dr Roehm. That is, the gnathologic view makes little or no sense, does not hold up well to the demands of clinical practice, and is more or less a perfunctory exercise. If clinical decisions are to be based solely on experience (and not science and evidence), then whose experience should practitioners trust?

Myths of orthodontic gnathology

J. Michael Hudson — 2010-02-01

After reading another opinion article by Rinchuse and Kandasamy (Rinchuse DJ, Kandasamy S. Myths of orthodontic gnathology. Am J Orthod Dentofacial Orthop 2009;136:322-9), I was moved to write this letter in hopes that the discussion of orthodontics, occlusion, and TMD could move on to something more constructive. Perhaps the pages of the AJO-DO could be used to focus attention on the areas in this discussion that unite us, not divide us. Perhaps, if we could focus on what is accepted, agreed upon by all concerned, and evidence based, we could work toward developing some guidelines that would be useful to orthodontists, the general orthodontic patient population, and orthodontic patients with TMD.

Authors' response

Donald J. Rinchuse, Sanjivan Kandasamy — 2010-02-01

We thank Dr Hudson for his letter about our recent article. We agree wholeheartedly that we as a specialty have concentrated far too long on issues that divide us, rather than those that unite us. Perhaps, many issues related to gnathology, occlusion, condylar position, and TMD are secondary to the core doctrines of orthodontics.

Standards of care

Arthur S. Burns — 2010-02-01

The October issue of the Journal had much to say about establishing standards of care. (Riolo ML, Vaden JL. Standard of care: why is it necessary? Am J Orthod Dentofacial Orthop 2009;136:494-6; Vaden JL, Riolo ML. How can the specialty establish a standard of care? Am J Orthod Dentofacial Orthop 2009;136:497-500; Turpin DL. Improve care with clinical practice guidelines. Am J Orthod Dentofacial Orthop 2009;136:475-6). The phrase “standard of care” is statutory language in all states under torts and negligence. A typical definition is “the prevailing professional standard of care for a given health care provider shall be that level of care, skill, and treatment which, in light of all relevant surrounding circumstances, is recognized as acceptable and appropriate by reasonably prudent similar health care providers.”

Authors' response

James L. Vaden, Michael L. Riolo — 2010-02-01

The interesting, legally crafted letter from Dr Burns elicits the following question. If you require a heart bypass operation, a hip replacement, or a colonoscopy (ugh!), would you prefer to have it done by a properly trained practitioner who performs it within the standard of care for that procedure? Malocclusion correction is not a life-threatening event. If it were, there would be accepted standards for all orthodontists that “guaranteed” the patient a good probability for a reasonable outcome. On a lighter note, even farmers must conform to a “standard” when worming cows. If the procedure is not done correctly, it has no value to the animal—or subsequently to the farmer!

Validity of 3-dimensional reconstruction and simulation of mandibular movement and occlusal contact

Li Hongbo — 2010-02-01

I read with interest the article on 4-dimensional analysis of stomatognathtic function (Terajima M, Endo M, Aoki Y, Yuuda K, Hayasaki H, Goto TK, et al. Four-dimensional analysis of stomatognathtic function. Am J Orthod Dentofacial Orthop 2008;134:276-87). This article dealt with computer-aided simulation of jaw movement and occlusal contact analysis. Although the authors should be applauded for several aspects of their study, it has some limitations to which I want to draw attention.

Postorthodontic root approximation after opening space for maxillary lateral incisor implants

Taylor M. Olsen, Vincent G. Kokich — 2010-02-01

Introduction: Orthodontic space opening during adolescence is a common treatment for congenitally missing maxillary lateral incisors. Because of continued facial growth and compensatory tooth eruption, several years can elapse between completion of orthodontic treatment for a teenage patient and implant placement. There are reports that, after successful orthodontic opening of the implant space, the central incisor and canine roots reapproximate during retention and prevent implant placement.Methods: To study this phenomenon, the records of 94 patients with missing maxillary lateral incisors were collected. Periapical and panoramic radiographs were used to measure intercoronal and interradicular distances between the central incisor and the canine adjacent to the missing lateral incisor before and after orthodontic treatment and at implant placement.Results: Although root approximation between the adjacent central incisor and canine during retention did not occur consistently, 11% of the patients experienced relapse significant enough to prevent implant placement.Conclusions: To ensure sufficient space for implant placement, we recommend at least 6.3 mm of intercoronal space and 5.7 mm of interradicular space between the adjacent central incisor and canine. A bonded wire or resin-bonded bridge will help to reduce root approximation that might occur during retention.

Editor's Summary and Q&A: Postorthodontic root approximation after opening space for maxillary lateral incisor implants

Taylor M. Olsen, Vincent G. Kokich — 2010-02-01

Primary failure of eruption and PTH1R: The importance of a genetic diagnosis for orthodontic treatment planning

2010-02-01

Introduction: Primary failure of eruption (PFE) is characterized by nonsyndromic eruption failure of permanent teeth in the absence of mechanical obstruction. Recent studies support that this dental phenotype is inherited and that mutations in PTH1R genes explain several familial cases of PFE. The objective of our study was to investigate how genetic analysis can be used with clinical diagnostic information for improved orthodontic management of PFE.Methods: We evaluated a family (n = 12) that segregated an autosomal dominant form of PFE with 5 affected and 7 unaffected persons. Nine available family members (5 male, 4 female) were enrolled and subsequently characterized clinically and genetically.Results: In this family, PFE segregated with a novel mutation in the PTH1R gene. A heterozygous c.1353-1 G>A sequence alteration caused a putative splice-site mutation and skipping of exon 15 that segregated with the PFE phenotype in all affected family members.Conclusions: A PTH1R mutation is strongly associated with failure of orthodontically assisted eruption or tooth movement and should therefore alert clinicians to treat PFE and ankylosed teeth with similar caution—ie, avoid orthodontic treatment with a continuous archwire.

Editor's Summary and Q&A: Primary failure of eruption and PTH1R: The importance of a genetic diagnosis for orthodontic treatment planning

2010-02-01

Introduction: Primary failure of eruption (PFE) is characterized by nonsyndromic eruption failure of permanent teeth in the absence of mechanical obstruction. Recent studies support that this dental phenotype is inherited and that mutations in PTH1R genes explain several familial cases of PFE. The objective of our study was to investigate how genetic analysis can be used with clinical diagnostic information for improved orthodontic management of PFE.Methods: We evaluated a family (n = 12) that segregated an autosomal dominant form of PFE with 5 affected and 7 unaffected persons. Nine available family members (5 male, 4 female) were enrolled and subsequently characterized clinically and genetically.Results: In this family, PFE segregated with a novel mutation in the PTH1R gene. A heterozygous c.1353-1 G > A sequence alteration caused a putative splice-site mutation and skipping of exon 15 that segregated with the PFE phenotype in all affected family members.Conclusions: A PTH1R mutation is strongly associated with failure of orthodontically assisted eruption or tooth movement and should therefore alert clinicians to treat PFE and ankylosed teeth with similar caution—ie, avoid orthodontic treatment with a continuous archwire.

Engineered cartilage heals skull defects

2010-02-01

Introduction: The purposes of this study were to differentiate embryonic limb bud cells into cartilage, characterize the nodules produced, and determine their ability to heal a mouse skull defect.Methods: Aggregated mouse limb bud cells (E12-E12.5), cultured in a bioreactor for 3 weeks, were analyzed by histology or implanted in 6 skull defects. Six controls had no implants. The mice were scanned with microcomputed tomography weekly. At 2 and 4 weeks, a mouse from each group was killed, and the defect region was prepared for histology.Results: Chondrocytes in nodules were mainly hypertrophic. About 90% of the nodules mineralized. BrdU staining showed dividing cells in the perichondrium. Microcomputed tomography scans showed increasing minerals in implanted nodules that completely filled the defect by 6 weeks; defects in the control mice were not healed by then. At 2 and 4 weeks, the control skull sections showed only a thin bony layer over the defect. At 2 weeks, bone and cartilage filled the defects with implants, and the implants were well integrated with the adjacent cortical bone. At 4 weeks, the implant had turned almost entirely into bone.Conclusions: Cartilage differentiated in the bioreactor and facilitated healing when implanted into a defect. Engineering cartilage to replace bone is an alternative to current methods of bone grafting.

Editor's Summary and Q&A: Engineered cartilage heals skull defects

2010-02-01

Introduction: The purposes of this study were to differentiate embryonic limb bud cells into cartilage, characterize the nodules produced, and determine their ability to heal a mouse skull defect.Methods: Aggregated mouse limb bud cells (E12-E12.5), cultured in a bioreactor for 3 weeks, were analyzed by histology or implanted in 6 skull defects. Six controls had no implants. The mice were scanned with microcomputed tomography weekly. At 2 and 4 weeks, a mouse from each group was killed, and the defect region was prepared for histology.Results: Chondrocytes in nodules were mainly hypertrophic. About 90% of the nodules mineralized. BrdU staining showed dividing cells in the perichondrium. Microcomputed tomography scans showed increasing mineral in implanted nodules that completely filled the defect by 6 weeks; defects in the control mice were not healed by then. At 2 and 4 weeks, the control skull sections showed only a thin bony layer over the defect. At 2 weeks, bone and cartilage filled the defects with implants, and the implants were well integrated with the adjacent cortical bone. At 4 weeks, the implant had turned almost entirely into bone.Conclusions: Cartilage differentiated in the bioreactor and facilitated healing when implanted into a defect. Engineering cartilage to replace bone is an alternative to current methods of bone grafting.

Influence of rapid palatal expansion on maxillary incisor alignment stability

2010-02-01

Introduction: The purpose of this retrospective study was to compare the long-term stability of maxillary incisor alignment in patients treated with and without rapid maxillary expansion (RME).Methods: The sample comprised 48 subjects with Class I and Class II malocclusions, treated without extractions with fixed edgewise appliances, divided into 2 groups according to the treatment protocol: group 1 comprised 25 patients (15 girls, 10 boys) at a mean initial age of 13.53 years (SD, 1.63), who had RME during orthodontic treatment. Group 2 comprised 23 patients (13 girls, 10 boys) at a mean initial age of 13.36 years (SD, 1.81 years), treated with fixed appliances without RME. Maxillary dental cast measurements were obtained at the pretreatment, posttreatment, and long-term posttreatment stages. Variables assessed were the irregularity index and maxillary arch dimensions. Intergroup comparisons were made with independent t tests.Results: Greater transverse increases were found during treatment in the group treated with RME. However, during the long-term posttreatment period, no significant difference was observed in the amount of incisor crowding relapse between the groups.Conclusions: RME did not influence long-term maxillary anterior alignment stability.

Editor's Summary and Q&A: Influence of rapid palatal expansion on maxillary incisor alignment stability

2010-02-01

Retrospective cone-beam computed tomography evaluation of temporary anchorage devices

2010-02-01

Introduction: Miniscrew impants as temporary anchorage devices (TADs) are becoming more popular in orthodontic tretment. Their ease of use allows orthodontists to place them in locations in the mouth that are convenient for orthodontic treatment mechanics. The aims of this study were to evaluate the location of TADs placed during orthodontic treatment and to relate the placement to the surrounding dentoalveolar structures.Methods: Three-dimensional cone-beam computed tomography scans were taken before and after placement of the TADs over a 6-month period as part of routine clinical protocol. The following parameters were recorded: placement site, length of the TAD in the alveolar bone, amount of contact with the periodontal ligament, and interroot distance between TADs.Results: Thirty-five TADs (19 in the maxilla, 16 in the mandible) were evaluated. The mean lengths of the TADs in alveolar bone were 5.29 ± 1.39 mm in the maxilla and 4.60 ± 0.86 mm in the mandible. The amounts of contact with the periodontal ligaments were 2.54 ± 0.81 mm (n = 13) in the maxilla and 2.72 ± 0.49 mm (n = 10) in the mandible. The interroot distance measurements were 2.78 ± 0.76 mm (n = 15) and 5.19 ± 4.42 mm (n = 16) in the maxilla and the mandible, respectively. Paired t tests indicated a significant difference in the interroot distance for mandibular teeth.Conclusions: Three-dimensional cone-beam computed tomography technology allows better visualization of TAD placement. Clinicians can expect 71.2% of the length of the screw section of the TAD to be embedded in the alveolar bone; the percentage is often higher in the maxilla than in the mandible. Of the 35 TADs, 65.2% were in contact with the periodontal ligament. There appears to be more space for TAD placement in the mandible than in the maxilla.

Editor's Summary and Q&A: Retrospective cone-beam computed tomography evaluation of temporary anchorage devices

2010-02-01

Impact of facial asymmetry in visual perception: A 3-dimensional data analysis

2010-02-01

Introduction: The aim of this controlled study was to analyze the degree and localization of 3-dimensional (3D) facial asymmetry in adult patients with cleft lip and palate (CLP) compared with a control group and its impact on the visual perception of faces.Methods: The degree of 3D asymmetry was analyzed with a novel method without landmarks in 18 adults with complete unilateral CLP and 18 adults without congenital anomalies. Furthermore, the CLP and control faces were rated for appearance, symmetry, and facial expression by 30 participants.Results: The results showed that adults with CLP had significantly greater asymmetry in their facial soft tissues compared with the control group. Moreover, the lower face, and particularly the midface, had greater asymmetry in the CLP patients. The perceptual ratings showed that adults with CLP were judged much more negatively than those in the control group.Conclusions: With sophisticated 3D analysis, the real morphology of a face can be calculated and asymmetric regions precisely identified. The greatest asymmetry in CLP patients is in the midface. These results underline the importance of symmetry in the perception of faces. In general, the greater the facial asymmetry near the midline of the face, the more negative the evaluation of the face in direct face-to-face interactions.

Editor's Summary and Q&A: Impact of facial asymmetry in visual perception: A 3-dimensional data analysis

2010-02-01

Results of a survey-based study to identify common retention practices in the United States

Manish Valiathan, Eric Hughes — 2010-02-01

Introduction: The purpose of this descriptive study was to use a carefully constructed, pilot-tested survey instrument to identify the most common orthodontic retainers and retention protocols prescribed in the United States as reported by active members of the American Association of Orthodontists.Methods: We randomly selected 2000 active members, stratified by region of practice, for the study. Information gathered included, but was not limited to, the types of retainers prescribed in the maxillary and mandibular arches, duration of full-time and part-time wear, use of fixed retainers, appliances fabricated in office vs commercial laboratories, the number of debonds per year, and retention appointment schedules. The survey consisted of 20 questions. Data were gathered on a categorical scale and analyzed.Results: We received 658 responses (32.9%) during a 12-week period. Maxillary Hawley retainers (58.2%) and mandibular fixed lingual retainers (40.2%) were the most commonly used. Most orthodontists prescribed less than 9 months of full-time wear of removable retainers and thereafter advised part-time, but lifetime wear. Most orthodontists (75.9%) did not instruct patients to have the fixed lingual retainers removed at a specific time. More orthodontists who prescribed Hawley retainers recommended longer full-time wear compared with clear thermoplastic retainers. The timing of scheduled retention appointments varied among clinicians and depended on the number of years in practice, the volume of patients debonded, and the type of prescribed retainer. The only regional difference associated with retainer design was the Northeast region, where mandibular fixed lingual retainers were used less frequently. Female orthodontists did not use mandibular fixed lingual retainers as often as their male counterparts.Conclusions: Maxillary Hawley and mandibular fixed lingual retainers are most commonly used. This study is the first to describe retention protocols and the scheduling of retention appointments in the United States.

Commentary

Straty Righellis — 2010-02-01

I congratulate the authors on a well-designed survey identifying common retention practices in the United States. However, I remind readers that this article describes what orthodontists do.

Pretreatment characteristics associated with orthodontic treatment duration

Monica A. Fisher, Reid M. Wenger, Mark G. Hans — 2010-02-01

Introduction: Pretreatment characteristics can assist orthodontists in accurately estimating treatment duration.Methods: This case-control study identified 400 patients, 9 to 18 years of age. Short treatment duration was 20 months or less, and long treatment duration was 30 months or longer. Potential pretreatment explanatory variables included planned treatment, sociodemographic, behavior, dental, skeletal, and soft-tissue characteristics. Univariable and multivariable logistic regression modeling was used to quantify the association between patient characteristics and treatment duration by reporting the unadjusted odds ratios (ORcrude), the adjusted odds ratios (ORadj), and the 95% confidence intervals (CIs).Results: Patients planned as nonextraction (ORadj = 2.3; 95% CI, 1.3-4.2), no deciduous teeth (ORadj = 3.0; 95% CI, 1.5-5.9), less than 80% overbite (ORadj = 2.4; 95% CI, 1.3-4.4), less than 6 mm of maxillary crowding (ORadj = 3.6; 95% CI, 1.7-7.7), and good oral hygiene (ORadj = 3.2; 95% CI, 1.3-1.8) were 2 to 3 times more likely to have short treatments. Patients with decreased lower facial height (ORadj = 3.4; 95% CI, 1.6-7.1), extractions (ORadj = 1.8; 95% CI, 1.0-3.2), deciduous teeth (ORadj = 1.9; 95% CI, 1.0-3.4), poor grades (ORadj = 2.0; 95% CI, 1.1-3.8), excessive overjet (ORadj = 2.3; 95% CI, 1.4-3.8), 80% or more overbite (ORadj = 2.0; 95% CI,1.2-3.6), and 6 mm or more of maxillary crowding (ORadj = 2.6; 95% CI,1.4-4.6) were 2 to 3 times more likely to have long treatments.Conclusions: Presence or absence of severe maxillary crowding, deciduous teeth, 80% overbite, and extractions were consistently, inversely, and independently associated with short and long treatment durations.

Longitudinal changes in mandibular arch posterior space in adolescents with normal occlusion

Li-Li Chen, Tian-Min Xu, Jiu-Hui Jiang, Xing-Zhong Zhang, Jiu-Xiang Lin — 2010-02-01

Introduction: The purpose of this study was to investigate the changes of available mandibular space in the posterior dental arch of teenagers from 13 to 18 years old.Methods: Longitudinal cephalograms of 28 adolescents (13 boys, 15 girls) with normal occlusion, selected from among 901 candidates, were taken annually from 13 to 18 years of age inclusively. Modified analyses with occlusal plane and occlusal plane perpendicular as reference planes were used to evaluate the changes of available space of the posterior mandibular arch.Results: From 13 to 18 years of age, significant differences of mandibular posterior space were found among ages and sexes. The total increases of available space were 5.12 mm in the girls and 5.79 mm in the boys. For girls before age 16 and boys before age 17, the increased available space was contributed mainly by resorption of bone on the anterior border of the ramus. Mesial drift of the dental arch did not occur until the eruption of the third molars. The average available spaces increased 1.22 mm in girls less than age 16 and 1.45 mm in boys less than age 17 per side per year.Conclusions: The prediction of available space in the posterior mandibular arch should be based on age and sex.

Survival analysis of orthodontic mini-implants

Shin-Jae Lee, Sug-Joon Ahn, Jae Won Lee, Seong-Hun Kim, Tae-Woo Kim — 2010-02-01

Introduction: Survival analysis is useful in clinical research because it focuses on comparing the survival distributions and the identification of risk factors. Our aim in this study was to investigate the survival characteristics and risk factors of orthodontic mini-implants with survival analyses.Methods: One hundred forty-one orthodontic patients (treated from October 1, 2000, to November 29, 2007) were included in this survival study. A total of 260 orthodontic mini-implants that had sandblasted (large grit) and acid-etched screw parts were placed between the maxillary second premolar and the first molar. Failures of the implants were recorded as event data, whereas implants that were removed because treatment ended and those that were not removed during the study period were recorded as censored data. A nonparametric life table method was used to visualize the hazard function, and Kaplan-Meier survival curves were generated to identify the variables associated with implant failure. Prognostic variables associated with implant failure were identified with the Cox proportional hazard model.Results: Of the 260 implants, 22 failed. The hazard function for implant failure showed that the risk is highest immediately after placement. The survival function showed that the median survival time of orthodontic mini-implants is sufficient for relatively long orthodontic treatments. The Cox proportional hazard model identified that increasing age is a decisive factor for implant survival.Conclusions: The decreasing pattern of the hazard function suggested gradual osseointegration of orthodontic mini-implants. When implants are placed in a young patient, special caution is needed to lessen the increased probability of failure, especially immediately after placement.

Proper mesiodistal angles for microimplant placement assessed with 3-dimensional computed tomography images

Hyo-Sang Park, Eun-Seok HwangBo, Tae-Geon Kwon — 2010-02-01

Introduction: To provide information about placement sites and angulations of microimplants between tooth roots, we analyzed 3-dimensional computed tomography images from 25 patients.Methods: The patients in the sample had good interdigitation, no restorations, and no arch length discrepancies in the posterior segments. Three-dimensional images of the maxillary and mandibular second premolars, first molars, and second molars were constructed. The distances and midpoints between the roots at 3 levels were calculated, and the angles between the lines connecting the midpoints and perpendicular lines to the occlusal plane at the contact points were also calculated.Results: The midpoints between the roots were located distally to the contact point and from the cervical to the apical areas. The lines connecting these midpoints from the cervix to the apex of the roots in the mandibular arch had more distal inclination than in the maxillary arch.Conclusions: To minimize root contacts, microimplants need to be inclined distally about 10° to 20° and placed 0.5 to 2.7 mm distally to the contact point to minimize root contact according to sites and levels, except into palatal interradicular bone between the maxillary first and second molars.

Apical root resorption in orthodontic patients with en-masse maxillary anterior retraction and intrusion with miniscrews

Eric J.W. Liou, Peter M.H. Chang — 2010-02-01

Introduction: The purposes of this retrospective study were to investigate the apical root resorption of maxillary incisors in orthodontic patients with en-masse maxillary anterior retraction and intrusion with miniscrews and the factors disposing a patient to apical root resorption.Methods: Fifty adult patients with maxillary protrusion were included; 30 were treated with miniscrews and extraction of the maxillary first premolars (group I), and 20 were treated with extraction of the maxillary first premolars (group II). For each patient, periapical films of the maxillary incisors and lateral cephalometric radiographs were taken before and after treatment to evaluate apical root resorption and cephalometric measurements. The intergroup differences were analyzed with the Student t test and the correlations between apical root resorption and cephalometric measurements were analyzed by the Pearson correlation.Results: The apical root resorption values were 16.0% to 20.0% (2.5-2.8 mm) in group I and 13.4% to 14.4% (2.1-2.3 mm) of the original root length in group II. Group I had significantly more severe Class II jaw discrepancy (ANB, 7.1° ± 1.9°) than did group II (ANB, 3.2° ± 2.9°). The amount of maxillary en-masse anterior retraction (8.2 ± 2.4 mm), the duration of treatment (28.3 ± 7.3 months), and apical root resorption of maxillary lateral incisors were significantly greater in group I than in group II. Apical root resorption of the maxillary central incisors was significantly correlated to the duration of treatment but not to the amount of en-masse retraction, intrusion, or palatal tipping of maxillary incisors.Conclusions: Miniscrew anchorage allows for more maxillary en-masse anterior retraction in patients with severe Class II cases. But the time needed for the greater amount of maxillary en-masse anterior retraction with miniscrew anchorage is longer and might dispose the patient to more apical root resorption.

Mechanical properties of coated superelastic archwires in conventional and self-ligating orthodontic brackets

Firas Elayyan, Nick Silikas, David Bearn — 2010-02-01

Introduction: Coated archwires have been introduced to improve esthetics during orthodontic treatment. Our aim was to investigate the mechanical properties of coated superelastic archwires compared with conventional superelastic archwires with conventional and self-ligating brackets.Methods: Four types of orthodontic archwires were investigated, 2 superelastic nickel-titanium and 2 coated Ultraesthetic archwires in 0.016-in and 0.018 × 0.025-in dimensions (all from G&H Wire, Greenwood, Ind). To achieve the same nominal size, the coated archwire is constructed from a smaller archwire that, when coated, reaches the nominal dimensions stated for the archwire. Conventional edgewise Orthos and Damon 2 self-ligating brackets (both from Ormco, Orange, Calif) were used with each wire. All specimens were tested in a universal testing machine in a 3-point bending test at a speed of 1 mm per minute and deflected for 2 mm. Loading and unloading forces were recorded and load-deflection curves plotted.Results: Coated superelastic wires produced statistically significantly lower forces in loading and unloading when compared with the superelastic nickel-titanium wires at most archwire deflections (P <0.01). For nickel-titanium wires, loading values ranged from 189 to 1202 g, whereas the respective values for coated wires were 124 to 772 g. For all wires, an increase in size resulted in an increase in force. Interactions between wire type (coated or uncoated) and bracket type were observed.Conclusions: Ultraesthetic coated archwires produced lower force values in loading and unloading compared with uncoated wires of same nominal size. The Damon 2 self-ligating bracket system produced lower force values in loading and unloading. The lowest forces were generated by the combination of Ultraesthetic coated archwires and Damon 2 self-ligating brackets.

Morphologic quantification of the maxilla and the mandible with cone-beam computed tomography

Toshio Deguchi, Shinya Katashiba, Toru Inami, Kelvin W.C. Foong, Chan Yiong Huak — 2010-02-01

Introduction: The purpose of this pilot study was to use cone-beam computed tomography (CBCT) to determine the volumes of the maxilla and the mandible in subjects with skeletal Class I, Class II, and Class III malocclusions. Hypothesis 1 was that the volume (size) of a skeletal Class II maxilla is larger than those of Class I and Class III. Hypothesis 2 was that the volume of a skeletal Class III mandible is larger than those of Class I and Class II.Methods: Thirty women patients were classified into 3 groups according to their skeletal pattern: skeletal Class I (0° ≤ANB <6°), Class II (ANB ≥6°) and Class III (ANB <0°). The volumes of the maxilla and the mandible were measured with CBCT. CB MercuRay (Hitachi Medico, Tokyo, Japan) and CB works software (CyberMed, Seoul, Korea) were used to process the images.Results: There was a trend that skeletal Class III subjects might have significantly greater mandibular volume compared with Class II subjects (P = 0.089). The ratios of maxilla-to-mandible volumes between the skeletal Class II and Class III groups were significantly different (P = 0.005). Differences were observed in the ratios of maxillary and mandibular volumes across the 3 groups.Conclusions: Hypotheses 1 and 2 were rejected; there was no trend for Class III subjects to have larger mandibles (P = 0.089) compared with Class II subjects. The ratio of the maxilla and mandible volumes in skeletal Class III subjects was significantly larger (P = 0.005) compared with Class II subjects.

Clinical and microbiological findings at sites treated with orthodontic fixed appliances in adolescents

Klara Kim, Kristin Heimisdottir, Urs Gebauer, G. Rutger Persson — 2010-02-01

Introduction: Fixed orthodontic appliances can alter the subgingival microbiota. Our aim was to compare the subgingival microbiota and clinical parameters in adolescent subjects at sites of teeth treated with orthodontic bands with margins at (OBM) or below the gingival margin (OBSM), or with brackets (OBR).Methods: Microbial samples were collected from 33 subjects (ages, 12-18 years) in treatment more than 6 months. The microbiota was assessed by the DNA-DNA checkerboard hybridization method.Results: Bacterial samples were taken from 83 OBR,103 OBSM, and 54 OBM sites. Probing pocket depths differed by orthodontic type (P <0.001) with mean values of 2.9 mm (SD, 0.6) at OBSM sites, 2.5 mm (SD, 0.6) at OBM sites, and 2.3 mm (SD, 0.5) at OBR sites. Only Actinomyces israelii (P <0.001) and Actinomyces naeslundii (P <0.001) had higher levels at OBR sites, whereas Neisseria mucosa had higher levels at sites treated with OBSM or OBM (P <0.001). Aggregatibacter actinomycetemcomitans was found in 25% of sites independent of the appliance.Conclusions: Different types of orthodontic appliances cause minor differences in the subgingival microbiota (A israelii and A naeslundii) and higher levels at sites treated with orthodontic brackets. More sites with bleeding on probing and deeper pockets were found around orthodontic bands.

Effects of ultrasonic, electric, and manual toothbrushes on subgingival plaque composition in orthodontically banded molars

2010-02-01

Introduction: Orthodontic appliances hinder mechanical plaque control. In this study, we evaluated the effect of self-performed supragingival plaque removal with ultrasonic, electric, and manual toothbrushes on subgingival plaque composition in orthodontically banded molars.Methods: Twenty-one patients wearing fixed orthodontic appliances were assigned to this single-blind crossover study. Samples of subgingival plaque were collected from banded molars, before and after each toothbrush usage period, for quantification of 22 bacterial species by the checkerboard DNA-DNA hybridization method. For each crossover, patients used a toothbrush for 30 days, followed by a washout period of 14 days.Results: The prevalence of Tannerella forsythia decreased significantly after a month of electric brush usage. In the manual brush group, the prevalences of Selenomonas noxia, Streptococcus sanguinis, and Prevotella melaninogenica also decreased significantly. However, there were no significant differences in the prevalences and levels of bacteria after usage of the ultrasonic brush. Intergroup comparisons showed no statistical differences among the 3 brushes for the microbiologic parameters.Conclusions: All 3 brushes generally reduced bacterial prevalences, and, although electric and manual toothbrushes showed some isolated significant variations, we found no superiority with any toothbrush type when used three times daily for 2 minutes on microbiologic parameters in orthodontically banded molars.

Cephalometric and electromyographic study of patients of East African ethnicity with and without anterior open bite

2010-02-01

Introduction: A review of the literature showed that there are disturbances of muscle activity and tongue function in patients with anterior open bite (AOB). However, most studies have had white subjects, even though open bite is more prevalent in black populations. In this pilot study, we examined jaw muscle activity and tongue pressure in East African black subjects.Methods: Ten subjects (4 boys, 6 girls; ages, 10.1-13.2 years) were recruited. A cephalometric comparison of subjects with and without AOB was performed. Surface electrodes were placed on the bilateral anterior temporalis, superficial masseter, superior orbicularis oris, and anterior digastric muscles. Electromyograms were recorded at rest, maximal voluntary clenching, chewing, and swallowing. Tongue pressure during rest and swallowing, and maximal bite force were also measured.Results: There was no statistically significant difference between the 2 groups in cephalometric measures (except in amount of open bite and overbite) and maximum bite force. During chewing, both groups showed similar coordinated activity patterns in the muscles, but the AOB subjects tended to show more electromyographic activity in the muscles of the balancing side. During clenching, the AOB subjects exhibited lower electromyographic activity compared with the controls. AOB subjects also had greater anterior tongue pressure during swallowing. Data from tongue pressure at rest were inconclusive.Conclusions: East African blacks appear to have neuromuscular and skeletal predispositions to AOB, but their vertical incisor relationships are variable. Factors in addition to those investigated might be involved.

In-vitro study of the cellular viability and nitric oxide production by J774 macrophages with ceramic, polycarbonate, and polyoxymethylene brackets

2010-02-01

Introduction: Studies show that ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade, releasing bisphenol-A and formaldehyde, respectively. In addition to the traditional cytotoxicity tests, the study of nitric oxide cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating its cytotoxic potential.Methods: We aimed to assess cellular viability by MTT (Sigma, St. Louis, Mo): 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide assay in a murine macrophage cell line J774 with esthetic brackets and quantify nitric oxide production by these macrophages. Cell cultures were evaluated at 3 times: 24, 48, and 72 hours.Results: Cellular viability in all groups was higher at 72 hours compared with 24 hours. This increase was significant in the control and ceramic brackets groups. Final means in the bracket groups showed no significant differences compared with the control group. Nitric oxide production was significantly greater in all groups at final time. There was no significant difference between the final means of the bracket groups and the control group, although polyoxymethylene brackets showed significantly greater means at 24 and 48 hours.Conclusions: Final means in the bracket groups showed no significant differences compared with the control group.

Pulp vitality after rapid palatal expansion

Jamin J. Cho, Stella Efstratiadis, Gunnar Hasselgren — 2010-02-01

Introduction: Although it has been suggested that orthodontic treatment might lead to changes in the dental pulp, no clinical study has attempted to investigate the incidence of pulp necrosis after orthodontic therapy. The purpose of this clinical trial was to determine whether pulp testing response is altered after rapid palatal expansion (RPE).Methods: Twenty-five adolescent patients (9 boys, 16 girls; ages, 10-16 years) participated in the study. A hyrax appliance was cemented on the first permanent molars and first premolars (when fully erupted). The appliance was activated twice daily (0.5 mm) for 2 weeks. An electric pulp tester (EPT) was used to test at the buccal cusp tips of the molars and premolars. Teeth that did not respond to the EPT were subsequently tested thermally with Endo Ice (Hygienic Corporation, Akron, Ohio).Results: All maxillary molars and erupted premolars of the 25 patients responded positively to pulp tests before cementation of the hyrax appliance. Of the 49 molars tested, 46 responded positively to the EPT, and 3 responded positively to the cold testing (CT). Of the 42 first premolars tested, 40 responded positively to the EPT and 2 to the CT. Of the 38 second premolars tested, 35 responded positively to the EPT and 3 to the CT. Two weeks after the initial activation of the hyrax appliance, 93 teeth in 17 subjects were tested. Of the 93 teeth, 73 teeth responded positively to the EPT and 20 to the CT. Three to 6 weeks after hyrax activation was discontinued, 59 teeth were tested; 48 tested positively to the EPT and 10 to the CT. One tooth (maxillary left first molar) did not respond to either EPT or CT. Finally, 3 to 9 months into retention, all molars and premolars of 23 subjects tested positive to pulp tests, 92 teeth to the EPT and 25 to the CT. The maxillary left first molar that had not responded to the tests at the 3-to-6 week check responded positively to the CT at the final check.Conclusions: After RPE therapy in children and adolescents, the pulp of the posterior permanent teeth examined in this study was vital.

Three-dimensional dental measurements: An alternative to plaster models

2010-02-01

Introduction: The aim of this study was to compare the accuracy of dental measurements taken with calipers on plaster dental casts and those from computed tomography scans of the dentition with a dental measurement program.Methods: The sample consisted of plaster dental models of 34 orthodontic subjects. Dental arch measurements, including mesiodistal widths of teeth, arch widths, arch lengths, arch perimeters, and palatal depths were made with the calipers. The patients were also scanned with computed tomography, and measurements were made digitally with a 3-dimensional-based dental measurements program (3DD, Biodent, Cairo, Egypt).Results: The results showed strong agreement in most measurements between the conventional method and the 3DD in the 3 planes of space. The mesiodistal measurements of the maxillary right and left second premolars, left central incisor, and right first molar, and the mandibular left and right central incisors, right canine, and left first premolar had fair agreement.Conclusions: Excellent agreement between the measurements with the conventional and 3DD methods in the 3 planes of space was found; 3DD can be an alternative to conventional stone dental models.

Methods for managing 3-dimensional volumes

2010-02-01

The introduction of 3-dimensional (3D) volumetric technology and the massive amount of information that can be obtained from it compels the introduction of new methods and new technology for orthodontic diagnosis and treatment planning. In this article, methods and tools are introduced for managing 3D images of orthodontic patients. These tools enable the creation of a virtual model and automatic localization of landmarks on the 3D volumes. They allow the user to isolate a targeted region such as the mandible or the maxilla, manipulate it, and then reattach it to the 3D model. For an integrated protocol, these procedures are followed by registration of the 3D volumes to evaluate the amount of work accomplished. This paves the way for the prospective treatment analysis approach, analysis of the end result, subtraction analysis, and treatment analysis.

Three-dimensional analysis of maxillary protraction with intermaxillary elastics to miniplates

2010-02-01

Introduction: Early Class III treatment with reverse-pull headgear generally results in maxillary skeletal protraction but is frequently also accompanied by unfavorable dentoalveolar effects. An alternative treatment with intermaxillary elastics from a temporary anchorage device might permit equivalent favorable skeletal changes without the unwanted dentoalveolar effects.Methods: Six consecutive patients (3 boys, 3 girls; ages, 10-13 years 3 months) with Class III occlusion and maxillary deficiency were treated by using intermaxillary elastics to titanium miniplates. Cone-beam computed tomography scans taken before and after treatment were used to create 3-dimensional volumetric models that were superimposed on nongrowing structures in the anterior cranial base to determine anatomic changes during treatment.Results: The effect of the intermaxillary elastic forces was throughout the nasomaxillary structures. All 6 patients showed improvements in the skeletal relationship, primarily through maxillary advancement with little effect on the dentoalveolar units or change in mandibular position.Conclusions: The use of intermaxillary forces applied to temporary anchorage devices appears to be a promising treatment method.

Mandibular “tripod” advancement of a Class II Division 2 deepbite malocclusion

2010-02-01

This case report describes the treatment of a 25-year-old woman with a Class II malocclusion, secondary to mandibular skeletal deficiency, and mild overclosure. Inferior surgical repositioning of the maxilla is often the treatment of choice for patients with maxillary vertical deficiency; however, this patient had borderline vertical deficiency that was treated with a mandibular “tripod” advancement (leveling of the mandibular arch after surgery) coupled with a setback and down-grafting genioplasty. The surgical-orthodontic treatment plan, combined with cosmetic dentistry, resulted in dramatically improved facial esthetics and occlusal relationships.

Earn 3 hours of CE credit

Michael Rennert — 2010-02-01

Meeting announcements

2010-02-01

AAO Annual Sessions

Directory: AAO Officers and Organizations

2010-02-01

American Journal of Orthodontics & Dentofacial Orthopedics

Table of Contents

Editor's Choice

Editors

Information for readers

Need and demand for orthodontic services: The final report

After 50 years in practice, the evidence is convincing

Gnathology lessons from a 1969 Oldsmobile engine

Authors' response

Myths of orthodontic gnathology

Authors' response

Standards of care

Authors' response

Validity of 3-dimensional reconstruction and simulation of mandibular movement and occlusal contact

Postorthodontic root approximation after opening space for maxillary lateral incisor implants

Editor's Summary and Q&A: Postorthodontic root approximation after opening space for maxillary lateral incisor implants

Primary failure of eruption and PTH1R: The importance of a genetic diagnosis for orthodontic treatment planning

Editor's Summary and Q&A: Primary failure of eruption and PTH1R: The importance of a genetic diagnosis for orthodontic treatment planning

Engineered cartilage heals skull defects

Editor's Summary and Q&A: Engineered cartilage heals skull defects

Influence of rapid palatal expansion on maxillary incisor alignment stability

Editor's Summary and Q&A: Influence of rapid palatal expansion on maxillary incisor alignment stability

Retrospective cone-beam computed tomography evaluation of temporary anchorage devices

Editor's Summary and Q&A: Retrospective cone-beam computed tomography evaluation of temporary anchorage devices

Impact of facial asymmetry in visual perception: A 3-dimensional data analysis

Editor's Summary and Q&A: Impact of facial asymmetry in visual perception: A 3-dimensional data analysis

Results of a survey-based study to identify common retention practices in the United States

Commentary

Pretreatment characteristics associated with orthodontic treatment duration

Longitudinal changes in mandibular arch posterior space in adolescents with normal occlusion

Survival analysis of orthodontic mini-implants

Proper mesiodistal angles for microimplant placement assessed with 3-dimensional computed tomography images

Apical root resorption in orthodontic patients with en-masse maxillary anterior retraction and intrusion with miniscrews

Mechanical properties of coated superelastic archwires in conventional and self-ligating orthodontic brackets

Morphologic quantification of the maxilla and the mandible with cone-beam computed tomography

Clinical and microbiological findings at sites treated with orthodontic fixed appliances in adolescents

Effects of ultrasonic, electric, and manual toothbrushes on subgingival plaque composition in orthodontically banded molars

Cephalometric and electromyographic study of patients of East African ethnicity with and without anterior open bite

In-vitro study of the cellular viability and nitric oxide production by J774 macrophages with ceramic, polycarbonate, and polyoxymethylene brackets

Pulp vitality after rapid palatal expansion

Three-dimensional dental measurements: An alternative to plaster models

Methods for managing 3-dimensional volumes

Three-dimensional analysis of maxillary protraction with intermaxillary elastics to miniplates

Mandibular “tripod” advancement of a Class II Division 2 deepbite malocclusion

Earn 3 hours of CE credit

Meeting announcements

Directory: AAO Officers and Organizations