Computational protocol: Analysis of correlation between initial alveolar bone density and apicalroot resorption after 12 months of orthodontic treatment withoutextraction

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Protocol publication

[…] A prospective study was carried out with a sample of 91 upper incisors in 47 patients, 11 years old or older who had participated in a previous study. All patients had a complete fixed appliance installed with straight-wire orthodontics at the clinics of the Orthodontic Postgraduate Program of the State University of Maringá and at Maringá Dental Association (Brazil) between July 2008 and April 2009. In selecting the sample, the following inclusion criteria were applied: Signed informed consent form; patients who were 11 years old or older; fully intact crown of upper incisors or only with proximal restorations; and scheduled orthodontic treatment without extractions and ⁄or incisor intrusion. The exclusion criteria were: Previous history of fixed orthodontic treatment; previous root resorption; history of dentoalveolar trauma to upper incisors; history of osteoporosis or rickets and hyperparathyroidism.All procedures were approved by the State University of Maringá Institutional Review Board, Brazil (190 ⁄ 2008). Each volunteer was submitted to periapical radiography of the upper incisor region either immediately prior to or immediately after bracket bonding (T1), as well as 12 months after orthodontic treatment (T2). Radiographs were taken using the RX Timex 70 C (Gnatus, Ribeirão Preto, SP, Brazil) and Pro 70-Intra (Prodental, Ribeirão Preto, São Paulo, Brazil) x-ray equipment operating with 70 kVp, 7 mA and a 0.25-second exposure time. A five-step 2 x 20 x 3.5 mm aluminum wedge (Al step-wedge) was attached to the apical region perpendicular to the film (Agfa Dentus M2 "Comfort"). Kodak developing and fixing solutions (Kodak do Brazil, Comércio e Indústria Ltda, São José dos Campos, SP, Brazil) were used to develop the radiographs. The radiographic film was processed manually using the time-temperature method. Development time was determined after verifying the liquid temperature (2 minutes in developer with temperature between 20 and 26oC). Intermediate washing was standardized at 30 seconds and fixing time was standardized at 10 minutes. Radiographic images were digitized using a scanner under 400 ppi resolution (ArtixScan 18000F, Microtek, São Paulo, SP, Brazil). [...] Tooth length (TL) and crown length (CL) of upper incisors (#11 and #21) at both evaluation times (TLT1 and TLT2; CLT1 and CLT2) were measured at a precision of 0.1 mm with the aid of CorelDRAW X4 software. , , , These measures corresponded to the distance from the incisal edge to the root apex and the greatest distance between the incisal edge and the cementum-enamel junction. The long axis of the tooth was used as reference (). To compensate for possible variations in inclination during radiograph taking at different times (presuming that the crown measure remains unaltered during treatment), , , expected tooth length at T2 was calculated using the following equation: , , Figure 2 TLT2 expected = CLT2 . TLT1/CLT1 The amount of EARR was determined by subtracting expected tooth length at T2 by tooth length at T2: EARR T2 = TLT2 expected - TLT2 The amount of EARR was expressed in percentage in relation to initial tooth length. 0% resorption was classified as absent; 1 to 4% was classified as rounding of roots; 4 to 8% was classified as mild; and 8 to 12% was classified as moderate. Intra-examiner reliability was statistically assessed by analyzing the differences between duplicate measures on the radiographic images of 25 randomly selected patients (tooth and crown length, optical densities of the alveolar bone and second step of the aluminum wedge) with a 15-day interval between measures at both T1 and T2. The error of the method was calculated using Dahlberg's formula: In which 'd' is the difference between pairs of measurements and 'n' is the number of pairs of measurements. Spearman's correlation coefficient (r) was also employed. Although no statistically significant differences were found between the first and second measures, the mean of each variable was used in the subsequent statistical tests to minimize random error. […]

Pipeline specifications

Software tools TiMEx, CorelDraw
Applications Miscellaneous, Phylogenetics
Organisms Homo sapiens
Diseases Root Resorption, Alveolar Bone Loss