American Journal of Orthodontics & Dentofacial Orthopedics

What was wrong with the old practice model?

Vincent G. Kokich — 2012-05-01

I can remember when some instructors in my orthodontic residency spoke fondly about their private practices in the “old days.” They recalled having only 1 or 2 treatment chairs, a receptionist who doubled as an assistant, an office that was less than 1000 square feet, and a total number of active patients that was somewhere around 100. As residents, we thought this was absurd. Why would anyone practice like this?

MI Paste Plus research

Diane Johnson — 2012-05-01

I have concerns about an article in the November 2011 issue of the AJO-DO examining the use of MI Paste Plus to prevent demineralization. It is an extremely important topic; we’ve been discussing this issue in the orthodontic literature since, well, apparently Angle’s day, since his 1907 text was included as a reference in the article. And we seem to be getting nowhere, as evidenced by the fact that there is no less, and probably more, demineralization in our patients than in the past.

Author’s response

Chung How Kau — 2012-05-01

Thank you very much for your letter. The placebo paste used in this trial did not contain fluoride. However, it would be difficult to extrapolate from the data that the positive results seen in the MI Paste Plus group were a direct result from either the casein phosphopeptide-amorphous calcium phosphate, the fluoride content in the paste, or both.

Orthodontic dental casts: The case against routine articulator mounting

Claudia Aichinger — 2012-05-01

With interest, I read the Point/Counterpoint discussion on articulator mounting of dental casts in the January 2012 issue of the AJO-DO. Some statements by Drs Rinchuse and Kandasamy raise many questions.

Authors' response

Donald J. Rinchuse, Sanjivan Kandasamy — 2012-05-01

We thank Dr Aichinger for her interest in our article. It appears that she is clutching at any possible excuse to support and justify a long-held orthodontic gnathologic view that does not fit well with the current best evidence—ie, evidence-based orthodontics. Dr Aichinger used the classic sympathy line of what would practitioners do when it comes to treating their own children and then goes on to say, “Why so much emotion about adding 1 additional tool [articulator mountings] in diagnosing orthodontic patients?” This has nothing to do with emotion and everything to do with evidence. If there is no outcome benefit after the routine use and incorporation of articulators in orthodontics, then what is the point of the exercise? Why should patients be put through additional procedures when there is no benefit in the long term? The bottom line here is that external measuring devices such as condylar position indicators, centric relation bite registrations, and articulators cannot accurately measure internal joint orthopedic positions or disorders. Furthermore, if there is no convincing evidence to support a particular centric relation position, what is the point of spending unproductive effort and time to place the condyles in a specific centric relation position that ultimately is not where clinicians actually think they are placing them?

Articulators in orthodontics

J. Michael Hudson — 2012-05-01

I want to thank all the authors who participated in the interesting and thought-provoking Point/Counterpoint on the use of articulators by orthodontists. Several points seem worthy of mention.

Tone of January Point/Counterpoint

Marc Yarascavitch — 2012-05-01

I enjoy reading the Point/Counterpoint feature that you initiated a year ago. It’s an excellent addition to the Journal. As a general dentist and an orthodontist-in-training, I find that these features offer helpful perspectives on topics commonly surrounded by fact, myth, and opinion that make them difficult to navigate. I appreciate your introduction to this feature, advising that “there are some controversial topics that could benefit from a timely, well-referenced discussion or debate, looking at both sides of the topic. This is the purpose of Point-Counterpoint.” It is indeed critical to get at the heart of what’s best for our patients, and an informed dialog is the way to do it.

Mounted dental casts

G. Frank Petrick — 2012-05-01

Evidence-based dentistry will probably never settle the use of articulators in orthodontics. I was not trained to mount models. One case convinced me to change: an innocent-looking, mild Class II malocclusion in an adult with a deep overbite. After the appliances were placed and the proprioception changed, the mandible repositioned into a borderline surgical case (surgery had not been discussed). I was able to finish the treatment without surgery, but it left a lasting impression on me. I began routinely mounting dental casts in the early 1980s. A superb orthodontist who read this letter commented that he had several similar patients who did require orthognathic surgery.

Bone anchored maxillary protraction

Ajay Mathur, N.G. Toshniwal, Om P. Kharbanda, Arvind Thakur — 2012-05-01

The thought-provoking article by Nguyen et al in the December issue reported on an assessment of maxillary protraction with bone anchorage. Comprehensive methods to treat maxillary deficiency are available in the orthodontic literature, but we thank the authors for opening new doors and concepts in the field. We have the following questions regarding their study.

Author’s response

Tung Nguyen — 2012-05-01

We thank Dr Mathur and his group for their interesting comments regarding in our article. Below are our responses to the questions that were asked. Our previous studies have also shown that bone-anchored maxillary protraction treatment did not produce downward rotation in the posterior region of the maxilla. We hypothesized, in our discussion, that the center of resistance of the maxilla might not be located above the maxillary canine by the infrazygomatic buttress as proposed by Teuscher or Hata et al but, rather, posteriorly to it. Under normal circumstances, counterclockwise rotation of the mandible is unfavorable and often contraindicated in Class III patients. Our protocol produced closure of the gonial angle with significant distal displacement of the posterior ramus. This, combined with slight distalization of the condyles and corresponding remodeling of the glenoid fossa, minimized the forward displacement of the chin while maintaining the mandibular plane angle. The 3-dimensional data from this study will be published in the July issue of the AJO-DO.

Growth patterns in identical twins

John Mew — 2012-05-01

I was interested in the online case report by Sugawara et al mainly because of their finding that 1-phase and 2-phase results “showed identical dentofacial characteristics,” whereas my own study on 12 identical twins found large contrasts between twins treated with functional orthodontics at a young age and their identical siblings treated at an older age by fixed appliances.

Authors' response

Junji Sugawara, Ravindra Nanda — 2012-05-01

We appreciate the interest Dr Mew has taken in this controversial topic on the orthopedic effects of early treatment. Since he appears to have conducted a study with a larger number of twins, we were interested in the insight that his article could provide. In Dr Mew’s twin study, published in 2007 in the World Journal of Orthodontics, we found that there was no objective evaluation of skeletal differences, but only differences of facial appearance and dental features. In addition, the sample and the material of his study were too heterogeneous to support his statement that his trademarked functional appliance, used during early treatment, is more effective than late treatment with traditional fixed appliances.

What's fair is fair

Peter M. Greco — 2012-05-01

Your last initial examination of the week is another transfer patient. It seems that you have been identified as a willing recipient of these patients, because the caller told your receptionist that she had contacted the 3 other offices in your town and learned that they do not accept transfer patients. You are soon to learn 1 reason why.

Residents' journal review

Barry Briss, Vicky Cartsos — 2012-05-01

Transverse maxillary hypoplasia exists in nondysgnathic syndromal, cleft lip and palate patients, or patients with craniofacial syndromes. There is no consensus regarding the surgical technique that should be used when orthodontic rapid maxillary expansion is not an option. The purpose of this article was to document the procedure of 3-segment osteotomy compared with 2-segment osteotomy. Unlike the 2-segment osteotomy, where the osteotomy is performed anteriorly between the central incisors, posterior to the incisive foramen along the nasal septum to the posterior margin of the hard palate, the 3-segment osteotomy is performed bilaterally between the lateral incisors and the canines, continuing to the posterior margin of the palate. The original sample consisted of 98 patients. Some were treated with a novel 3-segment osteotomy and others received the conventional 2-segment procedure for surgically assisted rapid maxillary expansion. Transverse maxillary dental and skeletal expansion, dental tipping, attachment loss, and anterior tooth inclination were evaluated on preoperative and postexpansion models and photographs of 47 of the patients. Greater and more symmetrical expansion, more dental tipping, and more anterior angulation were observed in the 3-segment osteotomy group compared with the 2-segment osteotomy group. These results were statistically insignificant. The median mesial papilla in the 3-segment osteotomy group exhibited a more esthetic outcome, and this was statistically significant. The 3-segment osteotomy, although more invasive, seems to provide a more esthetic result. More research is needed to identify a more stable, periodontally healthier, and symmetrical result with these procedures.

Conservative orthodontic treatment for a patient with a unilateral condylar fracture

Carlos Alberto Estevanell Tavares, Susiane Allgayer — 2012-05-01

Trauma to the mandible often causes condylar fracture. This article reports the conservative treatment of a 10-year-old girl with a unilateral condylar fracture, highlighting the diagnostic aspects involved and the strategy used. The conservative approach used for this patient—bionator followed by full fixed orthodontic appliances—provided adequate esthetic and functional results. The outcomes throughout the 7-year follow-up and the remodeling process of the condyle observed in the panoramic radiographs proved the success of this treatment.

Microdamage of the cortical bone during mini-implant insertion with self-drilling and self-tapping techniques: A randomized controlled trial

2012-05-01

Introduction: The purpose of this research was to evaluate microdamage accumulation after mini-implant placement by self-drilling (without a pilot hole) and self-tapping (screwed into a pilot hole) insertion techniques. The null hypothesis was that the mini-implant insertion technique would have no influence on microcrack accumulation and propagation in the cortical bones of the maxillae and mandibles of adult hounds.Methods: Mini-implants (n = 162; diameter, 1.6 mm; length, 6 mm) were placed in the maxillae and mandibles of 9 hounds (12-14 months old) with self-drilling and self-tapping insertion techniques. The techniques were randomly assigned to the left or the right side of each jaw. Each hound received 18 mini-implants (10 in the mandible, 8 in the maxilla). Histomorphometric parameters including total crack length and crack surface density were measured. The null hypothesis was rejected in favor of an alternate hypothesis: that the self-drilling technique results in more microdamage (microcracks) accumulation in the adjacent cortical bone in both the maxilla and the mandible immediately after mini-implant placement. A cluster level analysis was used to analyze the data on the outcome measured. Since the measurements were clustered within dogs, a paired-samples t test was used to analyze the average differences between insertion methods at both jaw locations. A significance level of 0.05 was used for both analyses.Results: The self-drilling technique resulted in greater total crack lengths in both the maxilla and the mandible (maxilla: mean difference, 18.70 ± 7.04 μm/mm2; CI, 13.29-24.11; mandible: mean difference, 22.98 ± 6.43 μm/mm2; CI, 18.04-27.93; P <0.05), higher crack surface density in both the maxilla and the mandible (maxilla: mean difference, 10.39 ± 9.16 μm/mm2; CI, 3.34-17.43; mandible: mean difference, 11.28 ± 3.41 μm/mm2; CI, 8.65-13.90; P <0.05).Conclusions: This study demonstrated greater microdamage in the cortical bones of adult hounds in both the maxilla and the mandible by the self-drilling insertion technique compared with the self-tapping technique.

Root damage and repair in patients with temporary skeletal anchorage devices

2012-05-01

Introduction: The aim of this study was to evaluate the reparative potential of cementum histologically after intentional root contact with a temporary skeletal anchorage device.Methods: Seventeen patients (8 male, 9 female; mean age, 16.2 years; range, 13.5-21.6 years) who were scheduled for extraction of 4 first premolars as part of their orthodontic treatment participated in this study. The roots of the premolars were intentionally injured with a temporary skeletal anchorage device. The teeth were extracted at 4, 8, or 12 weeks after the injury. Root contact with the temporary skeletal anchorage device was confirmed by using a stereomicroscope. Histologic samples were prepared. Demineralized serial sections were stained with eosin and hematoxylin, and cementum repair was assessed histomorphometrically.Results: Despite varying depths of the injuries, including involvement of dentin, reparative cementum formation was observed in all sections. Healing cementum was almost exclusively of the cellular type; 70% of all the teeth exhibited good repair by the end of week 12.Conclusions: This study established that healing of cementum takes place after an injury with a temporary skeletal anchorage device, and it is a time-dependent phenomenon.

Interrelationship between the position of impacted maxillary canines and the morphology of the maxilla

Yoojun Kim, Hong-Keun Hyun, Ki-Taeg Jang — 2012-05-01

Introduction: The aim of this study was to examine whether there is a relationship between the position of impacted maxillary canines and the morphology of the maxilla.Methods: The palatally impacted canine group included 18 boys and 27 girls with an average age of 12 years 9 months (±2 years 1 month). The buccally impacted canine group comprised 19 boys and 26 girls with an average age of 12 years 2 months (±1 year 4 months). Arch length/intermolar width × 100 was used as the value for comparison of maxillary arch shapes, and palatal vault depth/intermolar width × 100 was used to compare the shapes of palate between the 2 groups. Each category was directly measured from the diagnostic model.Results: Both the arch length/intermolar width × 100 and the palatal vault depth/intermolar width × 100 formulas showed statistically significant differences (P <0.0001), indicating differences in the shape of maxillary arch and the palatal vault between the 2 groups.Conclusions: The shape of the maxillary arch was narrower and longer in the palatally impacted canine group compared with the buccally impacted canine group, and the palatally impacted canine group had a deeper palatal vault than did the buccally impacted canine group.

Orthodontic tooth movement and root resorption in ovariectomized rats treated by systemic administration of zoledronic acid

2012-05-01

Introduction: The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken.Methods: Fifteen 10-week-old female Wistar rats were divided into 3 groups: ovariectomy, ovariectomy + zoledronic acid, and control. Only the ovariectomy and ovariectomy + zoledronic acid groups underwent ovariectomies. Two weeks after the ovariectomy, zoledronic acid was administered only to the ovariectomy + zoledronic acid group. Four weeks after the ovariectomy, 25-g nickel-titanium closed-coil springs were applied to observe tooth movement and orthodontically induced root resorption.Results: There were significant differences in the amounts of tooth movement and orthodontically induced root resorption between the ovariectomy and the control groups, and also between the ovariectomy and the ovariectomy + zoledronic acid groups. There was no statistically significant difference in tooth movement and orthodontically induced root resorption between the ovariectomy + zoledronic acid and the control groups. Zoledronic acid inhibited significantly more tooth movement and significantly reduced the severity of orthodontically induced root resorption in the ovariectomized rats. The ovariectomy + zoledronic acid group showed almost the same results as did the control group in both tooth movement and orthodontically induced root resorption.Conclusions: Zoledronic acid inhibits excessive orthodontic tooth movement and also reduces the risk of severe orthodontically induced root resorption in ovariectomized rats.

Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area

Michael Knösel, Mariana Bojes, Klaus Jung, Dirk Ziebolz — 2012-05-01

Introduction: There is a paucity of information with regard to the susceptibility of iatrogenic white spot lesion formation after inattentive, surplus orthodontic etching with 30% phosphoric acid and the subsequent provision or absence of adequate oral hygiene.Methods: Ninety sound enamel specimens were randomly allocated to 6 trial groups (n = 15 each) for etching with 30% phosphoric acid for either 15 seconds and standardized daily enamel brushing or no brushing, etching for 30 seconds with daily brushing or no brushing, or nonetched controls with brushing or no brushing. Nutritive acidic assaults were simulated by demineralization cycles 3 times per day for 1 hour with interim storage in artificial saliva. Lesion depths in terms of percentage of fluorescence loss (delta F, delta Q) and lesion extension compared with the baseline were assessed by using quantitative light-induced fluorescence after 2, 7, 14, 21, and 42 days. Etching duration, trial time elapse, and oral hygiene, as well as the significance of factor interactions, were analyzed with 3-way analysis of variance (α = 5%).Results: The impact of the factors of enamel brushing, trial time elapse, and etching each had a comparably significant effect on lesion progression. The effect of surplus etching on white spot lesion formation was significantly enhanced by the simultaneous absence of enamel brushing and also the progression of trial time. The combination of 30 seconds of surplus etching with inadequate oral hygiene was especially detrimental.Conclusions: Excessive surplus orthodontic etching of the complete labial enamel surface, instead of the bracket bases only, must be avoided to prevent iatrogenic white spot lesions. Etching times not exceeding 15 seconds are favorable.

In-vitro assessment of oxidative stress generated by orthodontic archwires

2012-05-01

Introduction: Several metals undergo redox cycling, producing free radicals and generating oxidative stress. The purpose of this study was to investigate in-vitro oxidative stress of orthodontic archwires made of various alloys.Methods: Mouse fibroblast cells L929 were exposed to 6 types of archwires, and the concentration of the oxidative stress marker 8-hydroxy-2′-deoxyguanosine in DNA was evaluated. Trypan blue dye was used in the determination of cell viability and numbers.Results: Standard nickel-titanium archwires generated the highest oxidative stress, significantly higher than all other wires and the controls (P <0.05), and coated nickel-titanium, copper-nickel-titanium, and cobalt-chromium were lower than nickel-titanium (P <0.05), but higher than titanium-molybdenum and the negative and absolute controls (P <0.05). Titanium-molybdenum and stainless steel generated the lowest stress. Nickel-titanium induced the lowest viability, lower than the negative and absolute controls and all other wires (P <0.05) except titanium-molybdenum. Stainless steel showed the highest viability. Nickel-titanium produced the highest inhibition of cell growth, higher than all samples (P <0.05) except the positive control and cobalt-chromium. The lowest inhibition was observed in stainless steel and titanium-molybdenum, lower than nickel-titanium, cobalt-chromium, and the positive control (P <0.05).Conclusions: All orthodontic archwires generate oxidative stress in vitro. Stainless steel archwires have the highest and nickel-titanium the lowest biocompatibility.

Three-dimensional biometric study of palatine rugae in children with a mixed-model analysis: A 9-year longitudinal study

Hong-Kyun Kim, Sung-Chul Moon, Shin-Jae Lee, Young-Seok Park — 2012-05-01

Introduction: The palatine rugae have been suggested as stable reference points for superimposing 3-dimensional virtual models before and after orthodontic treatment. We investigated 3-dimensional changes in the palatine rugae of children over 9 years.Methods: Complete dental stone casts were biennially prepared for 56 subjects (42 girls, 14 boys) aged from 6 to 14 years. Using 3-dimensional laser scanning and reconstruction software, virtual casts were constructed. Medial and lateral points of the first anterior 3 rugae were defined as the 3-dimensional landmarks. The length of each ruga and the distance between the end points of the rugae were measured in virtual 3-dimensional space. The measurement changes over time were analyzed by using the mixed-effect method for longitudinal data.Results: There were slight increases in the linear measurements in the rugae areas: the lengths of the rugae and the distances between them during the observation period. However, the amounts of the increments were relatively small when compared with the initial values and individual random variability. Although age affected the linear dimensions significantly, it was not clinically significant; the rugae were relatively stable.Conclusions: The use of the palatine rugae as reference points for superimposing and evaluating changes during orthodontic treatment was thought to be possible with special cautions.

Influence of thermoplastic retainers on Streptococcus mutans and Lactobacillus adhesion

Çağrı Türköz, Nehir Canigür Bavbek, Selin Kale Varlik, Gülçin Akça — 2012-05-01

Introduction: This study was designed to test the hypothesis that thermoplastic retainers influence oral microbial flora during the retention period because they prevent the flushing effect of saliva on dental and mucous tissues.Methods: Twenty-four orthodontic patients finished the study. After debonding, the patients were given thermoplastic retainers (Essix ACE 0.040-in plastic, Dentsply International, York, Pa) for both jaws and instructed to wear them all day. Plaque samples from tooth surfaces and saliva samples were collected from each patient just after debonding (T0), and on day 15 (T1), day 30 (T2), and day 60 (T3) of retention. The jaws were divided into 6 regions, and the data for each region were evaluated separately. Total viable Lactobacillus and Streptococcus mutans colonies were counted, and the numbers of the viable microorganisms were calculated.Results: The numbers of Lactobacillus colonies at T3 were higher than at T0, T1, and T2, and the difference between T0 and T3 was statistically significant (P <0.05). The numbers of S mutans colonies at T3 were higher than at T0, T1, and T2, and the differences between T0 and T1, and T1and T2 were statistically significant (P <0.05).Conclusions: Retention with thermoplastic retainers might create oral conditions conducive to S mutans and Lactobacillus colonization on dental surfaces.

Mesiodistal angulation and faciolingual inclination of each whole tooth in 3-dimensional space in patients with near-normal occlusion

2012-05-01

Introduction: An important objective of orthodontic treatment is to obtain the correct mesiodistal angulation and faciolingual inclination for all teeth. Current techniques are based on crown angulation and inclination standards, and not enough attention has been given to the roots. In this study, we report the mesiodistal angulation and faciolingual inclination of each whole tooth including the root in patients with near-normal occlusion.Methods: We screened 1840 patients who had cone-beam computed tomography scans taken before treatment to obtain a sample of 76 patients with near-normal occlusion. Using our custom University of Sourthern California root vector analysis software program, we digitized the crown and root centers to determine the “true” long axis of each tooth from where the mesiodistal angulation and the faciolingual inclination were measured.Results: The means and standard deviations for the mesiodistal angulation and the faciolingual inclination of each whole tooth were calculated. The maxillary angulations of the teeth started from approximately 6° for the central incisors, slightly increased for the lateral incisors, and peaked at 11° for the canines; then it gradually decreased to just above 0° for the first molars and eventually reached −6° for the second molars. The mandibular angulations started from about 0° for the incisors and increased to 17.5° for the second molars. The maxillary inclination was the highest at 33.5° for the central incisors, decreased to about 0° at the second premolars, and then increased for the 2 molars. The mandibular inclination also was the highest at 26.5° for the central incisors, decreased also to about 0° at the second premolars, and continued to decrease for the 2 molars. For the opposing tooth pairs, the interdental mesiodistal angulations always remained within 10° from one another, whereas the interdental faciolingual inclination increased from about 120° for the incisors to about 180° for the second premolars and the 2 molars.Conclusions: We obtained the average mesiodistal angulation and faciolingual inclination for each whole tooth measured from its long axis digitized on the cone-beam computed tomography volumetric images of 76 patients with near-normal occlusion. We found distinctive angulation and inclination relationships between the neighboring and opposing teeth. This information can be used in addition to the crown standards for positioning each whole tooth properly in the arches.

Three-dimensional computed tomography analysis of airway volume changes after rapid maxillary expansion

2012-05-01

Introduction: In this retrospective study with 3-dimensional computed tomography, we evaluated airway volume, soft-palate area, and soft-tissue thickness changes before and after rapid maxillary expansion in adolescents. Another purpose was to determine whether rapid maxillary expansion caused changes in the palatal and mandibular planes and facial height.Methods: The sample comprised 20 patients who were treated with rapid maxillary expansion. Spiral tomographs were taken before and 3 months after treatment. Reliability studies were performed, and then volumetric, soft-palate area, soft-tissue thickness, and cephalometric parameters were compared on the tomographs. Intraclass correlations were performed on the reliability measurements. Before and after rapid maxillary expansion measurements were compared by using Wilcoxon signed rank tests. Spearman correlation coefficients were used to evaluate the associations among the airway volume, soft-palate area, soft-tissue thickness, and cephalometric measurements. Significance was accepted at P ≤0.05 for all tests.Results: Intraclass correlation coefficients were ≥0.90 for all reliability measures. Significant increases from before to after rapid maxillary expansion were found in nasal cavity and nasopharynx volumes, and for the measurements of MP-SN, S-PNS, N-ANS, ANS-Me, and N-Me. Significant positive correlations existed between changes in PP-SN and N-ANS, and ANS-Me and N-Me.Conclusions: Rapid maxillary expansion causes significant increases in nasal cavity volume, nasopharynx volume, anterior and posterior facial heights, and palatal and mandibular planes.

Treatment of skeletal open-bite malocclusion with lymphangioma of the tongue

Chooryung J. Chung, Soonshin Hwang, Yoon-Jeong Choi, Kyung-Ho Kim — 2012-05-01

Lymphangioma of the tongue causes massive tongue enlargement, leading to difficulties in swallowing and mastication, speech disturbances, airway obstruction, and skeletal deformities such as open-bite malocclusion. Early reduction of tongue volume improved the excessive open bite in a young girl, but it was not sufficient to redirect the original hyperdivergent growth pattern. Orthodontic camouflage treatment was therefore rendered. Long-term evaluation after tongue-reduction surgery and orthodontic treatment is presented.

Multiple congenitally missing teeth treated with autotransplantation and orthodontics

Jae Hyun Park, Kiyoshi Tai, Kenji Yuasa, Daisuke Hayashi — 2012-05-01

Treatment of children with several congenitally missing teeth is challenging, because growth and development of the oral structures must be considered. The treatment options include retaining the deciduous teeth and postponing treatment until later or extracting the deciduous teeth and doing one of the following: allowing the space to close spontaneously, closing the space orthodontically, or in patients whose growth is finished, using a prosthetic or implant replacement. One other viable option, if donor teeth are available, is autotransplantation. The treatment plan for patients with missing teeth should be based on a comprehensive evaluation of the patient’s age, occlusion, and space requirements as well as on the size and shape of the adjacent teeth. This case report presents the management of a patient in the early mixed dentition with multiple missing teeth. The treatment consisted of a combination of autotransplantation of the maxillary right first premolar to the mandibular right first premolar region and orthodontic treatment with a 5-year follow-up after autotransplantation.

Arrested root formation of 4 second premolars: Report of a patient

Maria L. Pinzon, Siew-Ging Gong — 2012-05-01

The shape and size of tooth roots are genetically and phylogenetically predetermined. Clinical defects in root formation can manifest in the form of shortened roots caused by either root agenesis or root resorption. We report on a patient who came at age 7 years for space management. In the 2-year period after the initial visit, maxillary arch expansion was performed, followed by serial extractions of all 4 first premolars. A radiograph taken about 18 months after the serial extraction showed that although the crowns of all 4 second premolars had erupted fully into the arch, the roots were only about half of their normal length. With a family history of 1 sibling with a missing second premolar and the symmetrical distribution and pattern of the teeth in the 4 dental quadrants, we speculated that the arrested root development was due most likely to a genetic predisposition. Arrested root development is difficult to predict, but a potential warning sign is a family history of malformed or missing teeth. Proper, adequate, and accurate records continue to remain critical for both medical and legal purposes in the treatment of patients with potential problems in root agenesis.

Is the airway volume being correctly analyzed?

2012-05-01

Introduction: The aim of the study was to determine the most accurate threshold value for airway volume quantification based on specific experimental conditions.Methods: Ten scans from the airway prototype were obtained by using cone-beam computed tomography. The volume from each scan was measured with 8 values (25, 50, 70, 71, 72, 73, 74, and 75) of the threshold tool from the Dolphin software (Dolphin Imaging and Management Solutions, Chatsworth, Calif). The gold standard method used was the actual volume of the airway prototype, which was compared with the different threshold values. An intraclass correlation coefficient test was applied to evaluate the intraexaminer calibration and verify differences among the airway volumes measured in all cone-beam computed tomography scans. Analysis of variance with the Tukey post-hoc test was used to compare differences among the measurements with different threshold values with the gold standard.Results: The intraexaminer reliability was confirmed by the intraclass correlation coefficient, which was ≥0.99. The intraclass correlation coefficient used to verify the differences among the airway volume measurements in all cone-beam computed tomography scans was ≥0.98, showing that they were comparable. Analysis of variance and the Tukey post-hoc test showed that the volumes measured with the threshold values of the 25 and 50 filters had statistically significant differences from the gold standard. However, volumes measured with the threshold values of the 70, 71, 72, 73, 74, and 75 showed no statistically significant differences from the gold standard and among them.Conclusions: In our study for the cone-beam machine and the acquisition parameters used, the threshold value of the 73 used in Dolphin 3D software was the most accurate to measure airway volume, but the threshold values of the 70, 71, 72, 74, and 75 had no statistically significant differences compared with the gold standard, showing they are also reliable.

Digital signature of electronic dental records

Ivan Toshio Maruo, Hiroshi Maruo — 2012-05-01

Introduction: The purpose of this article is to examine the feasibility of digital signature technology to guarantee the legal validation of electronic dental records.Methods: The possible uses of digital signature technology, the actual use of digital signature technology to authenticate electronic dental records, the authentication of each part of the electronic dental record, the general legal principles involved, how to digitally sign electronic dental record files, and the limitations of this method are discussed.Results and Conclusions: It is possible to obtain electronic dental records that carry the same legal certainty as conventional, nonelectronic records. For this purpose, each part of the electronic dental records should be digitally signed by the author of the document.

Sample calculations for comparing proportions

Nikolaos Pandis — 2012-05-01

In the previous article, we introduced the concepts of power and type I and type II errors and gave an example of the required steps for sample-size calculations for comparing 2 means. In this article, we will perform a sample calculation for comparison of 2 proportions. Let us briefly remind ourselves of the information we need before we proceed with the example:

Orthodontic Pearls: A Clinician's Guide

Peter Sinclair — 2012-05-01

Dr Larry White is a well-respected clinician, author, and educator. He has authored or contributed to several books, published numerous articles, and edited several professional publications. He is currently on the faculty of the orthodontic department of Baylor College of Dentistry in Dallas, Texas.

Earn 3 hours of CE credit

Allen Moffitt — 2012-05-01

Directory: AAO Officers and Organizations

2012-05-01

Editors

2012-05-01

Information for Readers

2012-05-01

Online only abstract

2012-05-01

American Journal of Orthodontics & Dentofacial Orthopedics

What was wrong with the old practice model?

MI Paste Plus research

Author’s response

Orthodontic dental casts: The case against routine articulator mounting

Authors' response

Articulators in orthodontics

Tone of January Point/Counterpoint

Mounted dental casts

Bone anchored maxillary protraction

Author’s response

Growth patterns in identical twins

Authors' response

What's fair is fair

Residents' journal review

Conservative orthodontic treatment for a patient with a unilateral condylar fracture

Microdamage of the cortical bone during mini-implant insertion with self-drilling and self-tapping techniques: A randomized controlled trial

Root damage and repair in patients with temporary skeletal anchorage devices

Interrelationship between the position of impacted maxillary canines and the morphology of the maxilla

Orthodontic tooth movement and root resorption in ovariectomized rats treated by systemic administration of zoledronic acid

Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area

In-vitro assessment of oxidative stress generated by orthodontic archwires

Three-dimensional biometric study of palatine rugae in children with a mixed-model analysis: A 9-year longitudinal study

Influence of thermoplastic retainers on Streptococcus mutans and Lactobacillus adhesion

Mesiodistal angulation and faciolingual inclination of each whole tooth in 3-dimensional space in patients with near-normal occlusion

Three-dimensional computed tomography analysis of airway volume changes after rapid maxillary expansion

Treatment of skeletal open-bite malocclusion with lymphangioma of the tongue

Multiple congenitally missing teeth treated with autotransplantation and orthodontics

Arrested root formation of 4 second premolars: Report of a patient

Is the airway volume being correctly analyzed?

Digital signature of electronic dental records

Sample calculations for comparing proportions

Orthodontic Pearls: A Clinician's Guide

Earn 3 hours of CE credit

Directory: AAO Officers and Organizations

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