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Objective: To provide a critical overview of the effect of various orthodontic and/or dentofacial orthopedic interventions on three-dimensional volumetric changes in the upper airway. Materials and methods: Four databases were searched for clinical studies concerning 3D volumetric assessments based on CBCT before and after orthodontics interventions. The quality of the studies was assessed using the quality assessment tool of the National Heart, Lung and Blood Institute. After the use of inclusion and exclusion criteria, the pre-and post-treatment volumes were used to visualize the effect of various orthodontics interventions. Results: A total of 48 studies were included in this review and none of which were RCTs. The quality of all included studies was assessed as medium. Overall, there is a tendency for an increase in airway volumes after various orthodontic interventions, except for studies concerning extraction therapy with fixed appliances in adults, in which both increases and decreases in airway volumes have been reported. Conclusion: Orthodontic treatment by growth modification and non-extraction therapy with fixed appliances, regardless of the malocclusion, generally showed positive effects on the airway volume. Orthodontic treatment in combination with extractions does not provide an unambiguous insight. A consensus on the methodology of the airway measurement and nomenclature is urgently needed in order to gain insight into the effect of different interventions on three-dimensional airway changes. Clinical relevance: Various orthodontic treatments do not negatively influence the upper airway volume. However, extraction therapy in adults should be chosen with caution, especially in subjects belonging to a group susceptible to airway obstruction. [ABSTRACT FROM AUTHOR]

Objective: To investigate the cephalometric outcome and post-treatment changes following the orthodontic treatment involving the extraction of maxillary first molars in patients presenting with a Class II division 1 malocclusion. Methods: A retrospective longitudinal study was conducted involving 83 patients treated by fixed appliances and the extraction of 16 and 26. The mean age at commencement was 13.2 ± 1.5 years. Lateral cephalograms were available pre-treatment (T1), immediately post-treatment (T2), and at 2.6 years post-treatment (T3). The sample was divided into hypodivergent (n = 18), normodivergent (n = 17), and hyperdivergent (n = 48) facial types. Mean increments, standard deviations, and 95% confidence intervals were calculated for T2-T1 and T3-T2. Increments were tested using paired-samples t-tests, and variables between groups by applying ANOVA followed by Tukey's post hoc test. Linear regression was used to examine the effect of facial type, age, and gender. Results: Significant changes occurred during treatment for most cephalometric variables. Post-treatment, the growth pattern showed a tendency to return to the original form. Facial type had only a minor influence on cephalometric increments during and after treatment. Conclusions: Post-treatment skeletal, soft tissue, and dentoalveolar changes were limited. Facial type had only a minor influence during and after treatment and care must be taken to control lower incisor inclination. [ABSTRACT FROM AUTHOR]

Bacterial adhesion to biomaterial surfaces constituting the bracket–adhesive–enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with which bacteria adhere to the surfaces of these junction materials, as the strength of these forces will determine how easy it will be to remove the bacteria. We compared the adhesion forces of five initially colonizing and four cariogenic strains of bacteria to an orthodontic adhesive, stainless steel, and enamel, with and without a salivary conditioning film. Adhesion forces were determined using atomic force microscopy and a bacterial probe. In the absence of a salivary conditioning film, the strongest bacterial adhesion forces occurred to the adhesive surface (−2.9 to −6.9 nN), while adhesion forces to the enamel surfaces were lowest (−0.8 to −2.7 nN). In the presence of a salivary conditioning film, adhesion forces were reduced strongly, to less than 1 nN, and the differences between the various materials were reduced. Generally, however, initial colonizers of dental hard surfaces presented stronger adhesion forces to the different materials (−4.7 and −0.6 nN in the absence and presence of a salivary conditioning film, respectively) than cariogenic strains (−1.8 and −0.5 nN). [ABSTRACT FROM AUTHOR]

Objective. To investigate the effect of age on root resorption and distribution along different parts of the root during prolonged light force application. Material and methods. Orthodontic appliances were placed in two groups of 30 rats (one group 6 weeks old, the other 9-12 months old), with contralateral sides as controls. Groups of animals were killed at 1, 2, 4, 8, and 12 weeks. At the study site, incidence was counted as either 1 (with resorption) or 0 (without); severity was measured as the summed length of all resorption lacunae as a percentage of study total root length. Results. Young and adult rats had the same incidence of root resorption in the early phase (<4 weeks), and both increased in the late phase (4-12 weeks) to the same level. Severity of resorption increased with prolonged tooth movement only in adult rats. However, there was no age-related difference in either the early or the late phase. In both groups, the middle part of the root had the highest incidence of resorption; the most severe resorption occurred exclusively at this part. Conclusion. Orthodontic intervention even with light forces increased both the incidence and severity of root resorption, the more so in the middle part of the root. Adult rats had increased incidence and severity with prolonged tooth movement. [ABSTRACT FROM AUTHOR]

This review aimed to evaluate studies on cytokines in the gingival crevicular fluid (GCF) during orthodontic treatment, summarizing the regulation patterns of the most commonly studied cytokines and exploring their clinical implications. To achieve this, a number of key databases were searched using MESH terms and free text terms. An additional search was made by reference tracking. The procedures suggested by the QUOROM statement were followed. Data from the included studies were extracted into orthodontic mechanics, GCF sampling/handling methods, and cytokine measurements. From the 85 relevant studies identified, 23 studies could be included. Common drawbacks consisted mainly of inadequacies in the study design (e.g. short duration and small number of study subjects). The most consistent result was a peak of cytokine levels at 24 h. Associations existed between prostaglandin E2 (PGE2) and interleukin-1β (IL-1β) and pain, velocity of tooth movement, and treatment mechanics. Interleukin-1β and PGE2 showed different patterns of up-regulation, with IL-1β being more responsive to mechanical stress and PGE2 more responsive to synergistic regulation of IL-1β and mechanical force. The results might be taken to support, at the cellular level, the use of light continuous forces for orthodontic treatment. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate tooth movement characteristics in relation to root resorption in young and adult rats. Two groups of 30 rats each (aged 6 wk and 9–12 months, respectively) were used. Standardized orthodontic appliances were placed to move the maxillary molars mesially. Animals were killed 1, 2, 4, 8, and 12 wk after the beginning of the experiment and their jaws were processed for histomorphometric analysis. In parasagittal sections of ‘pressure zones’ the extent of root resorption was measured and expressed as percentage of total root length. Whereas a negative correlation was found between the velocity of tooth movement and the extent of root resorption, a positive correlation was noted between the amount/duration of tooth movement and root resorption, but only in adult rats. The duration of tooth movement showed the highest correlation coefficient and the smallest 95% confidence interval. In younger animals, correlations were weak, and other factors are likely to be involved in the individual susceptibility to root resorption. [ABSTRACT FROM AUTHOR]

The aims of this study were to perform a systematic review of the use of rats as a model for experimental tooth movement, to give a critical evaluation of the use of elastics as a force delivery system, and to describe a newly designed well-defined model for tooth movement in rats. The literature from 1981 to 2002 indicates that in 57 per cent of animal studies on orthodontic tooth movement, rats were used, but in many of these investigations the experimental set-up was poorly documented. Only three of the 159 studies fulfilled the inclusion criteria for a good model: a force magnitude of less than 20 cN; moving molar(s) mesially; an experimental duration longer than 2 weeks; and no extra experimental condition such as drug intervention. As more than one-quarter of the studies on tooth movement in rats used elastics to produce an orthodontic force, and as the forces they produced and their force decay during decompression are unknown, their mechanical characteristics on decompression were tested. Elastics stored under dry conditions or in water showed significant force decay from around 45 N to almost O N within the first 0.2 mm of decompression. With regard to the above-mentioned shortcomings of using rats as a model for tooth movement, a newly designed experimental appliance for tooth movement in rats was evaluated. It proved to be stable and simple and able to deliver a continuous and constant force as low as 10 cN on all three molars together during an experimental period of 12 weeks without interference in animal welfare, and was able to compensate for the effects of molar distal drift and continuous incisor eruption. [ABSTRACT FROM AUTHOR]

Data sources Medline, Medline In-Process, LILACS (Latin American and Caribbean Health Sciences Literature), PUBMED, Embase, Web of Science and the Cochrane Library were searched. Search terms were rapid palatal expansion or rapid maxillary expansion (RME) and tooth or dental changes. Reference lists from retrieved articles were also examined.Study selection For inclusion, an article had to satisfy the following criteria: describe a controlled clinical trial; have dental arch measurements made for cephalometric radiographs or dental casts; and include no surgical treatment that could affect RME effects during the evaluation period. Studies without an adequate control to factor out normal growth changes were excluded.Data extraction and synthesis Selected articles were independently evaluated by three researchers. Interexaminer discrepancies were resolved by discussion to reach a consensus. A summary of sample size, retention period, measurement error and evaluation method were listed in a table.Results The search identified 164 articles, of which four met the inclusion criteria. From the final four articles, two measured changes using dental casts and two assessed changes using radiographs (one with lateral cephalometric radiographs and one with posteroanterior radiographs). Based on direct model treatment, clinically significant long-term maxillary molar width increase (3.7–4.8 mm) could be achieved. Because of crown tipping, the reported long-term increase varied according to the reference point used for measurements. The range of maxillary cuspid arch width expansion was more consistent and was similar for adolescents and adults (2.2–2.5 mm). Less mandibular molar and cuspid arch width expansion was attained in adults compared with adolescents. A significant overall gain was found in the maxillary (6 mm) and mandibular (4.5 mm) arch perimeter in adolescents treated with RME and edgewise appliances. When comparing radiographically the early-treated and late-treated groups with their respective controls, there was a significant gain of the maxillary intermolar width (2.7 and 3.5 mm, respectively) in both treated groups. No statistically or clinically significant differences were found in molar vertical position or in incisor inclination.Conclusions Similar maxillary molar and cuspid expansion could be found in adolescents and young adults. Significantly less indirect mandibular molar and cuspid expansion was attained in young adults compared with adolescents. A significant overall gain in the maxillary and mandibular arch perimeter was found in adolescents. More transverse dental arch changes were found after puberty than before, but the difference may not be clinically significant. No anteroposterior dental changes were found on lateral cephalometric radiographs.Evidence-Based Dentistry (2005) 6, 93–94. doi:10.1038/sj.ebd.6400358 [ABSTRACT FROM AUTHOR]

Data sources Medline, Medline In-Process and other Medline nonindexed citations, LILACS, Pubmed, Embase, Web of Science and the Cochrane Library were searched. Search terms were rapid palatal expansion or rapid maxillary expansion (RME), bone and bones or skeletal changes. Reference lists from retrieved articles were also examined.Study selection For inclusion, an article had to satisfy the following criteria: describe controlled clinical trials; make measurements for facial radiographs (anteroposterior and lateral cephalograms); and include no surgical or simultaneous treatment that could alter RME effects during the evaluation period. Articles without an adequate control group to factor out normal growth changes were excluded.Data extraction and synthesis Selected articles were independently evaluated by three researchers. Interexaminer discrepancies were resolved by discussion until a consensus was reached. A summary of sample size, retention period, measurement error and radiographs were listed in a table. A quality checklist of methods used was developed to evaluate the selected articles.Results The search identified 188 articles, of which three met the inclusion criteria. From the final three articles, one measured transverse changes, two anteroposterior changes, and two vertical changes. The only statistically significant difference in skeletal width increase for subjects before and after the peak pubertal growth spurt was lateronasal width (+1.5 mm). For the early-treated group, the maxillary width increase was significant (3 mm), but not for the late-treated group (0.9 mm). Regarding anteroposterior changes in the maxilla and mandible, no significant alterations were found. Short-term and long-term vertical skeletal changes associated with RME appeared to be restricted to the maxilla. The magnitude of change was small and had little, if any, clinical significance.Conclusions Long-term transverse skeletal maxillary increase is approximately 25% of the total dental expansion for prepubertal adolescents. Better long-term outcomes are expected in transverse changes because of RME in less skeletally mature patients. RME did not appear to produce clinically significant anteroposterior or vertical changes in the position of the maxilla and mandible. The conclusions from this systematic review should be considered with caution because only secondary-level evidence was found. Long-term randomised clinical trials (RCT) are needed.Evidence-Based Dentistry (2005) 6, 92. doi:10.1038/sj.ebd.6400359 [ABSTRACT FROM AUTHOR]