The European Journal of Orthodontics - current issue

Perception of discomfort during initial orthodontic tooth alignment using a self-ligating or conventional bracket system: a randomized clinical trial

Scott, P., Sherriff, M., DiBiase, A. T., Cobourne, M. T. — 2008-06-06

The aim of this study was to compare the degree of discomfort experienced during the period of initial orthodontic tooth movement using Damon3^TM self-ligating and Synthesis^TM conventional ligating pre-adjusted bracket systems. Sixty-two subjects were recruited from two centres (32 males and 30 females; mean age 16 years, 3 months) with lower incisor irregularity between 5 and 12 mm and a prescribed extraction pattern, including lower first premolar teeth. These subjects were randomly allocated for treatment with either bracket system. Fully ligated Damon^TM 0.014-inch Cu NiTi archwires were used for initial alignment in both groups. Following archwire insertion, the subjects were given a prepared discomfort diary to complete over the first week, recording discomfort by means of a 100 mm visual analogue scale at 4 hours, 24 hours, 3 days, and 1 week. The subjects also noted any self-prescribed analgesics that were taken during the period of observation. Data were analysed using repeated measures analysis of variance.

There were no statistically significant differences in perceived discomfort levels between the two appliances; discomfort did not differ at the first time point and did not develop differently across subsequent measurement times. Overall, this investigation found no evidence to suggest that Damon3 self-ligating brackets are associated with less discomfort than conventional pre-adjusted brackets during initial tooth alignment, regardless of age or gender.

Torque expression of self-ligating brackets compared with conventional metallic, ceramic, and plastic brackets

Morina, E., Eliades, T., Pandis, N., Jager, A., Bourauel, C. — 2008-06-06

The purpose of this research was to investigate the torque capacity of active and passive self-ligating brackets compared with metallic, ceramic, and polycarbonate edgewise brackets. Six types of orthodontic brackets were included in the study: the self-ligating Speed and Damon2, the stainless steel (SS), Ultratrimm and Discovery, the ceramic bracket, Fascination 2, and the polycarbonate bracket, Brillant. All brackets had a 0.022-inch slot size and were torqued with 0.019 x 0.025-inch SS archwires. For this purpose, the labial crown torque of an upper central incisor was measured in a simulated intraoral clinical situation using the orthodontic measurement and simulation system (OMSS). A torque of 20 degrees was applied and the correction of the misalignement was simulated experimentally with the OMSS. Each bracket/wire combination was measured five times. Maximum torquing moments and torque loss were determined. The results were analysed with one-way analysis of variance, with the bracket serving as the sole discriminating variable, and the Tukey test at the 0.05 level of significance.

The ceramic bracket (Fascination 2) presented the highest torquing moment (35 Nmm) and, together with a SS bracket, the lowest torque loss (4.6 degrees). Self-ligating, polycarbonate, and selective metallic brackets demonstrated almost a 7-fold decreased moment developed during insertion of a 0.019 x 0.022-inch SS wire into a 0.022-inch slot and a 100 per cent increase in loss.

Effects of rapid maxillary expansion on Holdaway soft tissue measurements

Kilic, N., Kiki, A., Oktay, H., Erdem, A. — 2008-06-06

The objective of the present study was to evaluate short-term soft tissue changes caused by rapid maxillary expansion (RME) in 18 subjects (15 females and 3 males) (mean age 13 years 6 months) with a bilateral posterior crossbite. Lateral cephalograms of the patients were obtained at three different time points: before RME (T1), after maxillary expansion (mean = 0.82 month) (T2), and after retention (mean = 5.95 months) (T3). Holdaway soft tissue measurements were used for the evaluation of soft tissue changes. Data were analysed statistically by means of paired t-tests.

The facial soft tissue angle decreased (P < 0.05), and H angle and skeletal profile convexity increased significantly (P < 0.001) at T2. During T3, the increase in the facial soft tissue angle and the decrease in H angle were minimal and not significant, while skeletal profile convexity significantly decreased (P < 0.001). The results of this study indicate that RME may affect Holdaway soft tissue measurements.

A preliminary evaluation of pre-treatment hypodontia patients using the Dental Aesthetic Index. How does it compare with other commonly used indices?

Shelton, A. T., Hobson, R. S., Slater, D. — 2008-06-06

There is currently no specific occlusal index related to hypodontia and there is a paucity of published literature on this subject. The aim of this study was to determine the relationship, if any, between the Peer Assessment Rating (PAR) Index, the Index of Complexity, Outcome and Need (ICON), and the Dental Aesthetic Index (DAI) score and the severity of hypodontia. All new patients attending the Newcastle Dental Hospital hypodontia clinic between February 2002 and March 2003 were included in the study. Of the 60 patients, two were excluded as the models were unavailable and one because they were predominantly in the primary dentition, making scoring impractical. The patient casts were scored with respect to PAR, ICON, and DAI. The mean patient age at presentation was 12 years, with a standard deviation of 1.89 and a range of 9–16 years, and a female to male ratio of 1.1:1.

A significant positive correlation, using Kendall tau b, was found between the number of missing teeth, excluding third molars, and the DAI score ( = 0.215, P = 0.027). There was no significant positive correlation between PAR ( = –0.186, P = 0.056) and ICON ( = 0.017, P = 0.861) score and the number of missing teeth. The results of this investigation indicate that further research is required in order to assess if the DAI could be used to determine whether or not to refer hypodontia patients for specialist advice.

Can persistence of primary molars be predicted in subjects with multiple tooth agenesis?

Kjaer, I., Nielsen, M. H., Skovgaard, L. T. — 2008-06-06

The purpose of this research was to create a method for predicting the persistence of primary molars in patients with multiple agenesis. Dental pantomographs (DPTs) from 51 males with agenesis of 5–17 teeth and 54 females with agenesis of 5–21 teeth were investigated. All patients (6 years 9 months to 16 years 7 months) had agenesis of one or both lower second premolars. Patients with ectodermal dysplasia and craniofacial anomalies were not included. The DPTs were classified into two groups according to tooth morphology and agenesis pattern.

Group I—ectodermal symptoms: screwdriver-shaped maxillary central incisors, invaginations in incisors or narrow incisors, taurodontic molar roots, and atypical agenesis. At least two of these ectodermal symptoms had to be present for classification into group I.

Group II: one or none of the criteria for group I.

Each group was subdivided according to the number of missing teeth. The degree of root resorption of the lower second primary molar was analysed and converted to a metric scale for statistical analysis. Ectodermal status (group I versus group II) was analysed as a binary outcome with agenesis and gender as covariates (logistic regression), whereas ordinary multiple regression was performed in order to study the dependency of root resorption score on gender, ectodermal status, and age.

The study showed that subjects with agenesis of more than seven teeth belonged more often to group I than group II, also when correcting for age differences. Root resorption of the primary molars was more severe in group I than in group II.

Agenesis of mandibular second premolars with retained primary molars. A longitudinal radiographic study of 99 subjects from 12 years of age to adulthood

Bjerklin, K., Al-Najjar, M., Karestedt, H., Andren, A. — 2008-06-06

In subjects with agenesis of the second mandibular premolar teeth, the primary molar may be left in situ. The long-term prognosis of a retained primary molar has not been established in any study that included large number of patients. The aim of this investigation was to monitor the survival of retained mandibular second primary molars, from 12–13 years of age to adulthood. The material comprised the radiographs of 99 subjects, 37 males and 62 females, with retained primary molars and agenesis of 149 mandibular second premolars. In subjects with bilateral agenesis, only one randomly selected primary molar was included to ensure that all primary molars were statistically independent units. Three variables were recorded on intraoral radiographs at 11 registration stages starting at 12–13 years of age: the distance between the permanent molar and the premolar abutting the retained primary molar, infraocclusion of the primary molar, and resorption of the primary molar roots. The mean age at the final registration was 24 years 7 months, [standard deviation (SD) 5.3 3 years, range 18.25–45.44 years]. Paired t-tests were used to analyse changes in the variables and intraclass correlation coefficient (ICC) to determine whether all primary molars could be included in the analyses.

During the observation period, only seven of the 99 primary molars were lost due to extensive root resorption, infraocclusion, or caries. Long-term survival may be expected in more than 90 per cent of patients with retained primary molars with agenesis of mandibular second premolars.

Assessment of vertical facial and dentoalveolar changes using panoramic radiography

Nohadani, N., Ruf, S. — 2008-06-06

The purpose of the study was to analyse longitudinal vertical facial and dentoalveolar changes using panoramic radiographs (PRs) and to compare the results with measurements on lateral cephalometric radiographs (LCRs) in order to determine whether, under certain circumstances, the radiation dose for a patient may be reduced by taking only a PR instead of a PR and a LCR. Pre- and post-treatment PRs and LCRs of 30 (15 females and 15 males) orthodontically treated adolescents (mean age pre-treatment 10.9 years, post-treatment 13.4 years) were analysed using Pearson's correlation coefficients and gender differences using Fisher's z-transformation.

The results revealed that most variables exhibited larger absolute values on PRs than on LCRs. Comparison of dentoskeletal morphology between the LCRs and the PRs revealed moderate to high, mostly statistically significant, interrelations both before and after orthodontic treatment. The lowest correlations were found for the maxillary jaw base angle (NL/H; r= 0.35***) and the highest for the gonial angle (ML/RL; r = 0.90***). However, when assessing the combined growth and treatment changes from before to after treatment, only weak to moderate, not statistically significant, interrelations were found between LCRs and PRs. Anterior face height (AFH; r = 0.43***), the mandibular plane angle (ML/H; r = 0.06*), and the distance of the incisal tip of the most extruded mandibular incisor to the ML-line (ii-ML; r = –0.21*) were the only statistically significant parameters. The average group differences for growth and treatment changes, however, were small for most parameters.

Analysis of vertical facial and dentoalveolar parameters on PRs delivers a moderate approximation to the situation depicted on LCRs. However, PRs cannot be recommended for the analysis of individual longitudinal changes in vertical facial and dentoalveolar parameters.

Overjet as a predictor of sagittal skeletal relationships

Zupancic, S., Pohar, M., Farcnik, F., Ovsenik, M. — 2008-06-06

Skeletal relationships in the sagittal plane do not always correspond with dental relationships. The aim of this study was to determine in which type of malocclusion the correlation between overjet and skeletal sagittal parameters assessed by lateral cephalogram analysis is the highest. The extent to which overjet can predict skeletal relationships in the sagittal plane was also assessed.

Eighty-three subjects fulfilled the inclusion criteria (40 males and 43 females, mean age 16.3 ± 4.3 years). Overjet was measured on study casts and sagittal skeletal relationships were analysed on lateral cephalograms. ANB angle, Wits appraisal, and convexity at point A were determined. Mean values and standard deviations of measured parameters were calculated for Class I, Class II division 1, and Class III malocclusion subjects. Correlation between overjet measured on study casts and sagittal skeletal parameters measured on lateral cephalogram was calculated. Overjet as a predictor of skeletal relationships was assessed by means of linear regression analysis.

A statistically significant positive correlation (P < 0.01) was found between the values of overjet and ANB (r = 0.690), overjet and Wits appraisal (r = 0.750), and overjet and convexity at point A (r = 0.608) when assessing the whole sample. When linear regression between overjet and cephalometric parameters was assessed separately in Class I, Class II division 1, and Class III malocclusion subjects, the percentage of variability was statistically significant in just four pairs.

The findings show that overjet is a good predictor of sagittal relationship only in subjects with a Class II division 1 malocclusion.

Does the degree of advancement during functional appliance therapy matter?

Rabie, A. B. M., Al-Kalaly, A. — 2008-06-06

The aim of this study was to assess the effect of varied degrees of mandibular advancement on condylar growth. Three hundred and thirty five 35-day-old female Sprague–Dawley rats were randomly divided into 10 experimental groups (n = 10) and five control groups (n = 5) for analysis of new bone formation and 10 experimental groups (n = 14) and five control groups (n = 14) for molecular analysis. The experimental animals were fitted with bite-jumping appliance to advance the mandible 2 and 4 mm. The rats were sacrificed on days 3, 7, 14, 21, and 30. A computer-assisted image analysing system was used to assess the quantity of new condylar bone formation. Molecular analysis utilizing real-time reverse transcription–polymerase chain reaction was used to assess the different levels of mRNA expression of different growth markers in the condyle.

One-way analysis of variance (ANOVA), with a Bonferroni multiple comparison test, showed significantly more newly formed bone in the 4 mm group compared with the 2 mm and control groups on days 21 and 30 (P < 0.05). Most of the examined growth markers demonstrated a significant increase during the 4 mm advancement (P < 0.05). Indian hedgehog (Ihh) mRNA showed a 7- and 5-fold change, parathyroid hormone-related peptide (PTHrP) a 5.2- and 3-fold change and type II collagen a 9.6- and 3.7-fold change in the 4 and 2 mm advancement groups, respectively.

Varied degrees of mandibular advancement result in different quantities of new bone formation and levels of expression of growth members: Ihh, PTHrP, and type II collagen.

Comparative evaluation of micro-implant and headgear anchorage used with a pre-adjusted appliance system

Ma, J., Wang, L., Zhang, W., Chen, W., Zhao, C., Smales, R. J. — 2008-06-06

The aim of this study was to compare and evaluate the anchorage effectiveness of using either micro-implants or extraoral headgear with the McLaughlin–Bennett–Trevisi (MBT) system.

Thirty young Chinese adults (14 males and 16 females) aged 18–22 years with anterior bimaxillary protrusion were divided randomly into two equal groups, treated with the MBT system anchored by either micro-implants or headgear. Nine measurements obtained before and after treatment from lateral cephalometric radiographs were assessed for the two groups, using the Mann–Whitney U test with = 0.05 for statistical significance.

The maxillary incisors in the micro-implant group were significantly more retracted and intruded, while the lower incisors were more lingually inclined, than in the headgear group. The occlusal and mandibular planes were rotated more counterclockwise in the micro-implant group than in the headgear group (P < 0.05).

Compared with headgear anchorage, micro-implant anchorage may counteract clockwise rotation of the occlusal and mandibular planes and result in different final positions for the maxillary and mandibular incisors.

Relationship between dental arch width and vertical facial morphology in untreated adults

Forster, C. M., Sunga, E., Chung, C.-H. — 2008-06-06

The objectives of this study were to investigate if a relationship exists between dental arch width and the vertical facial pattern determined by the steepness of the mandibular plane, and to examine the differences in dental arch widths between male and female untreated adults. Lateral cephalograms and dental casts were obtained from 185 untreated Caucasians (92 males, 93 females) between 18 and 68 years of age with no crossbite, minimal crowding, and spacing. The angle of the mandibular plane (MP) to the anterior cranial base (SN) was measured on cephalograms of each patient. Dental casts were used to obtain comprehensive dental measurements including maxillary and mandibular intercanine, interpremolar, and intermolar widths, as well as the amount of crowding or spacing. The arch widths of males and females were analysed and the differences between them were tested for significance using a Student's t-test. Regression analysis was used to determine the statistical significance of the relationships between MP–SN angle and dental arch width and crowding or spacing.

The results showed that male arch widths were significantly larger than those of females (P < 0.05). For both males and females, there was a trend that as MP–SN angle increased, arch width decreased. It was concluded that dental arch width is associated with gender and facial vertical morphology. Thus, using individualized archwires according to each patient's pre-treatment arch form and width is suggested during orthodontic treatment.

Prediction of arch length based on intercanine width

Paulino, V., Paredes, V., Gandia, J. L., Cibrian, R. — 2008-06-06

Arch length (AL), intercanine width (ICW), and intermolar width (IMW) are essential for diagnosis and treatment planning and are closely related factors in orthodontics. The aim of the present study was to determine correlations between these measurements and to predict some of these measurements based on others.

The dental casts of 197 Spanish patients (119 females and 78 males) with a mean age of 18 years (11–26 years) in the permanent dentition attending the Orthodontic Department of the University of Valencia, Spain, were selected. ICW, IMW, and AL on each dental cast were measured using a previously tested digital method. Correlation between variables was determined using Pearson's correlation coefficient. Linear regression analysis was applied and the 95 per cent confidence intervals (CIs) for slope and intercept were determined.

The data showed very high correlations between ICW and AL, both for the upper and lower arches and for males and females, r = 0.925. This coefficient was very close to 1, indicating a linear relationship. The regression equation for AL and ICW was AL = 1.36 ICW + 29.39 for both arches. There was very high correlations between AL and ICW for the upper and lower arches and a regression equation between both magnitudes was established indicating that the size of one factor can be predicted by knowing the other. For an increase of 1 mm in ICW, the AL increases approximately 1.36 mm with a 95 per cent CI (1.30–1.42).

Mechanobiology of tooth movement

Henneman, S., Von den Hoff, J. W., Maltha, J. C. — 2008-06-06

This review describes the mechanical and biological signalling pathways during orthodontic tooth movement and provides an update of the current literature. A theoretical model is introduced to elucidate the complex cascade of events after the application of an orthodontic force to a tooth. In this model, the events are divided into four stages: matrix strain and fluid flow, cell strain, cell activation and differentiation, and remodelling. Each stage is explained in detail and discussed using recent literature.

Identification of dentine sialoprotein in gingival crevicular fluid during physiological root resorption and orthodontic tooth movement

Kereshanan, S., Stephenson, P., Waddington, R. — 2008-06-06

Root resorption is an unwanted effect of orthodontic tooth movement. Analysis of dentine proteins in gingival crevicular fluid (GCF) is a potentially safer method of quantifying root resorption compared with conventional radiographic methods. This study aimed to identify and quantify the dentine-specific matrix protein, dentine sialoprotein (DSP), released into GCF during physiological root resorption and orthodontic tooth movement. GCF was collected using micropipettes from 50 second primary molar sites undergoing physiological root resorption in 9- to 14-year olds [coronal group (Rc) with advanced resorption (n = 33) and apical group (Ra) with minimal resorption (n = 17)] and 20 subjects aged 8–14 years with erupted mandibular second premolars (control group). In addition, GCF was collected from 20 patients undergoing treatment with fixed appliances at two time points, immediately prior to orthodontic intervention (T0) and 12 weeks following commencement of fixed appliance therapy (T1). GCF samples were analysed for DSP using an immunoassay and levels semi-quantified using image analysis. To determine differences between the means of the various experimental and control groups, data based on the relative optical density volumes, were statistically analysed using a parametric t-test.

DSP was raised in sites that were undergoing physiological resorption compared with the non-resorbing controls (P < 0.05). Notably, DSP was detected in some control samples. There was no difference in DSP levels for the Rc or Ra groups. DSP was also raised in GCF samples of teeth at 12 weeks following commencement of fixed appliance therapy (P < 0.001). The results highlight the potential for measuring DSP in GCF as a biomarker to monitor root resorption. Dentine is likely to be the major source for DSP in GCF, although alternative origins of bone and cementum are possible.

In vitro evaluation of a method for obtaining periapical radiographs for diagnosis of external apical root resorption

Gegler, A., Fontanella, V. — 2008-06-06

This in vitro study was conducted to evaluate a method to obtain reproducible periapical radiographs, using individualized positioning devices, of upper central incisors submitted to simulated orthodontic movement. Linear measurements of tooth length were carried out on 29 extracted human central incisors. The teeth were radiographed in a tissue simulator, at different inclinations in the bucco-lingual direction (0 initial, 0 control, –10, –5, +5, and +10 degrees). The radiographs were digitized and quantitative analysis of tooth length was carried out using an electronic ruler.

The linear measurements of tooth length were reproducible (r = 0.99) for repeated measurements as well as in the comparison of the initial and control images at 0 degree, where measurements did not differ significantly (analysis of variance, P = 0.827) in radiographs with different angulations. These results show that the method proposed for obtaining in vitro periapical radiographs results in reproducible images of tooth length, even when orthodontic movement is simulated by inclination of the tooth up to 20 degrees in the bucco-lingual direction.

Time-lapse observation of rat periodontal ligament during function and tooth movement, using microcomputed tomography

2008-06-06

The aim of this study was to observe the time-lapse changes in the rat periodontal ligament (PDL) during function and tooth movement. Under Nembutal anaesthesia, time-lapse changes in the thickness of the PDL of the first molars were investigated in five 12-week-old adolescent rats with microcomputed tomography. Three-dimensional (3D) images were reconstructed from the data. Histological observation was also performed, using undecalcified frozen sections of the maxillary first molar area.

The PDL appeared as a radiolucent furrow on the 3D images. A slight change in the thickness of the PDL was observed 1 hour after initiation of orthodontic force loading, which became significant after 6 hours, with the appearance of pressure–tension zones during the tooth movement. These changes were more significant 3 days after orthodontic loading.

Histological observation of the lingual cervical PDL (pressure zone) in nine 12- to 13-week-old rats demonstrated that the periodontal space had become narrow and the cellular elements appeared to be densely packed in the narrowed PDL 6 hours after orthodontic loading. Degeneration of tissues appeared 3 days after loading. Observation of the buccal cervical PDL (tension zone) demonstrated that the PDL was extended 6 hours after orthodontic force loading, and the extension continued for up to 3 days. Alkaline phosphatase activity was distributed in the PDL, except for the degenerating tissues in the pressure zone 3 days after loading.

The results suggest that the periodontal reaction was initiated within 6 hours after orthodontic force loading, which was related to the structural changes of the PDL. The changes probably induced an early response in individual cells of the PDL.

Critical thinking. Understanding and evaluating dental research, 2nd edition (2007)

Ren, Y. — 2008-06-06

Erratum

2008-06-06