The KPG index--a novel 3D classification system for maxillary canine impactions.

INTRODUCTION: Advancements in Cone Beam Computed Tomography (CBCT) have improved localization of impacted canines. The KPG index is the first 3-D classification system for classifying the position of canines based on their distance from the norm (1). The aim of this study was to determine if this index provides an estimate of the time necessary to treat an impacted canine using closed eruption. MATERIALS AND METHODS: CBCT scans of 28 impacted canines at The University of Texas School of Dentistry at Houston Department of Orthodontics were classified using the KPG index. The scores and categories were compared to the time from surgical exposure to proper positioning. RESULTS: Four canines were classified as "Easy," 11 as "Moderate," 9 as "Difficult," and 4 as "Extremely Difficult." Average treatment times associated in months were: "Easy"--11.23, "Moderate"--11.36, "Difficult"--12.76, and "Extremely Difficult"--13.23. CONCLUSIONS: The KPG index currently cannot be confirmed as an accurate means of estimating treatment time for an impacted canine. Further verification studies should include larger sample sizes and compare differing mechanics. However, there are limitations to 2-D imaging; therefore, the 3-D CBCT images and the KPG index, with further validation, will become increasingly valuable to orthodontists.

Bond strength comparison of color change adhesives for orthodontic bonding.

This study investigated whether three different color change light-cured orthodontic bonding adhesives have comparable shear bond strengths to a conventional light-cured orthodontic bonding adhesive. The sample of 240 bovine incisors was divided into four groups of 60 each. Each group tested one of four orthodontic bonding adhesives: 3M Unitek Transbond PLUS, Ormco Gréngloo, Ormco Blúgloo, and 3M Unitek Transbond XT (control). The four groups were further divided into two subgroups of 30 with shear bond strength tested at two different times (15 minutes and 24 hours) post-bond. The shear bond strength was measured on a universal testing machine. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. The average shear bond strength was greater at 24 hours than at 15 minutes for Transbond PLUS, Blúgloo, and Transbond XT. For Gréngloo, the average shear bond strength was greater at 15 minutes than at 24 hours. Gréngloo tested at 15 minutes had the highest average shear bond strength. Gréngloo tested at 24 hours had the lowest average shear bond strength. All four orthodontic bonding adhesives demonstrated bond strengths considered to be clinically acceptable for orthodontic purposes.

Longitudinal growth changes of the cranial base from puberty to adulthood. A comparison of different superimposition methods.

OBJECTIVE: To investigate the stability of cranial reference landmarks from puberty through adulthood and to compare the displacement of these landmarks among the superimposition methods of Björk, Ricketts, Steiner, and the proposed tuberculum sella-wing (T-W) reference line. MATERIALS AND METHODS: The sample consisted of serial lateral cephalometric radiographs of 30 Class II division 1 patients taken at the pretreatment (T1; mean age, 11.98 years), posttreatment (T2; mean age, 15.32 years) and postretention (T3; mean age, 32.12 years) periods. All cephalometric radiographs were superimposed at the cranial base according to the overall superimposition methods of Björk, Ricketts, Steiner, and the T-W method. The horizontal and vertical displacements of cranial landmarks (nasion, wing, tuberculum sella, sella, basion, and pterygomaxillare) were assessed by paired t-test according to Björk's structural method. One-way analysis of variance (ANOVA) was used for comparison of the displacement of cranial landmarks among the superimposition methods. RESULTS: The tuberculum sella and wing were the most stable cranial landmarks of the cranial base. The stability of sella and pterygomaxillare points were somewhat questionable. Nasion and basion were highly variable. The displacements of all cranial landmarks were similar between the Björk and T-W methods in all study periods. Most of the cranial landmarks displaced similarly in the horizontal direction among the methods. Vertically, the behaviors of the cranial landmarks were frequently different. CONCLUSIONS: T-W is the most similar superimposition method to Björk's structural method; thus, it is a reliable method for examining overall facial changes.

Temporary anchorage devices for tooth movement: a review and case reports.

BACKGROUND: Temporary anchorage devices (TADs) are immediately loaded miniscrews and osseointegrated palatal implants that are placed to control tooth movement during orthodontic treatment and removed when the treatment is completed. They are a relatively new addition to the dental armamentarium and can be used in some cases to replace traditional orthodontic extraoral appliances. Because placement requires a surgical procedure, orthodontists often refer patients to periodontists for this stage of the overall treatment plan. METHODS: The purpose of this article is to introduce TADs to the periodontal community by reviewing their purpose, various systems that are available, indications for use, site selection, and surgical technique. Case reports are included to illustrate this new treatment approach. RESULTS: Placement of osseointegrated implants for restorative purposes is an established procedure in most periodontal offices. Although placement of TADs is a modification of these familiar techniques, most of these devices serve a very different purpose, involving new loading protocols with no expectation of osseointegration in patients usually not receiving concomitant periodontal therapy. CONCLUSIONS: Periodontists' knowledge of soft and hard tissue anatomy and their ability to manage soft tissue position them well to collaborate with orthodontists in this multidisciplinary treatment. However, as with every new modality, clinicians need to understand the specific uses and limitations of TADs and work closely with their referring orthodontists in identifying patients for whom miniscrew implants are a viable option. Periodontal practices are based primarily on referrals from dental colleagues, and the concept of periodontists working cooperatively with orthodontists is not new. Including TAD placement among the services periodontists offer provides another opportunity to further this relationship and to establish periodontists as appropriate resources for this segment of orthodontic treatment.