To estimate the applicability of potential sites for insertion of orthodontic mini-implants (OMIs) by a systematic review of studies that used computed tomography (CT) or cone beam CT to evaluate anatomical bone quality and quantity parameters, such as bone thickness, available space, and bone density.
Materials and methods:
Medline and the Cochrane Database of Systematic Reviews were searched to identify all relevant papers. Several key words were used, such as computerized/computed tomography, mini-implants, and OMIs. The anatomical variables that were assigned in each article to a specific site suggesting it as the ideal or best alternative were assessed separately and evaluated with a scoring system.
Twenty-two articles were included in the study. The most favorable areas for OMI insertion in the maxilla are proposed between the first and second molars buccally and palatally. The best area in the mandible is also between the first and second molars, both buccally and lingually. In the palate, the paramedian area 3 to 6 mm posterior to and 2 to 9 mm lateral to the incisive foramen was identified as the best site for OMI placement.
Despite the heterogeneity of the studies, there was considerable agreement regarding the optimal site for OMI insertion among most studies that investigated anatomical hard tissue parameters based on CT or CBCT data. In this respect, the posterior area from the second premolar to the second molar is the best option for OMI placement in alveolar bone.
"Regarding the human jaws at various heights of the alveolar crest characterizing the interradicular zones, the buccal mandibular posterior sites showed statistically greater bone densities compared to the related maxilla-sites, while the differences in the anterior areas were not significantly different . The correlation between CT or CBCT and the success rate of OMIs in the alveolar bone was determined from a literature review . It was concluded that the posterior area is the best site for inserting mini implants, with no preference for the left or right side. "
[Show abstract][Hide abstract] ABSTRACT: Objectives: Orthodontic mini implants can be inserted at the interradicular site. The bone quality at this site may affect the stability and anchorage of the implant. Bone density is clinically evaluated by Hounsfield units (HU) obtained from cone beam CT (CBCT). The objective of this study was to determine the correlations between HU, microhardness and cortical bone thickness of interradicular site at various segments (anterior/posterior) and aspects (buccal/lingual) of both jaws in a swine model.Materials and methods: Eight mandible and maxilla swine bones were scanned by CBCT. The HU and thickness of the above-mentioned sites were determined. Then, a Knoop microhardness test was applied and the Knoop Hardness Number was obtained (KHN).
The mandible parameters spread over a wider range than the maxilla. The buccal aspect of the maxilla had higher HU and KHN values than the mandible. The lingual aspect of the mandible had higher KHN values than the maxilla. Posterior segments had higher HU and KHN values. The thickness of the alveolar cortical bone was greater in the maxilla than in the mandible. Correlations were found between HU and KHN for 3 of the 4 sites (anterior or posterior, buccal or lingual) of the mandible only. No correlations were found for the maxilla. Upon pooling the HU and KHN data for the whole jaw, correlation was found for the maxilla as well.
Relying on HU values as a predictor of cortical bone hardness should be considered with caution.
Head & Face Medicine 04/2014; 10(1):12. DOI:10.1186/1746-160X-10-12 · 0.85 Impact Factor
"Recent digital volumetric imaging studies analysed palatal thickness and revealed that the thickest part of the palate is in the anterior region and that in the posterior region, mini-screws of appropriate lengths can also be placed ,[26-28], which makes all proposed screw positions reasonable. The thick palatal bone allows wide and long screws to be used, as planned by several participants. "
[Show abstract][Hide abstract] ABSTRACT: Background
The aim of the survey was to obtain information on the treatment plan preferences, mechanics and characteristics of temporary anchorage device (TAD) application using a single case presented to orthodontists in Switzerland.
A structured questionnaire to be completed by all study participants with case-specific (treatment plan including mechanics and TAD usage) and general questions (general fixed appliance and TAD usage as well as professional, educational and demographic questions) together with an orthodontic borderline case was utilised. The case was a female adult with dental Class II/2, deep bite and maxillary anterior crowing, who had been treated in childhood with extraction of four premolars and fixed appliance followed by wisdom tooth extraction.
The response rate was 24.4% (108 out of 443). The majority (96.3%, 104) proposed comprehensive treatment, while 3.7% (4) planned only alignment of maxillary teeth. 8.3% (9) included a surgical approach in their treatment plan. An additional 0.9% (1) combined the surgical approach with Class II mechanics. 75.1% (81) decided on distalization on the maxilla using TADs, 7.4% (8) planned various types of Class II appliances and 3.7% (4) combined distalization using TADs or headgear with Class II appliances and surgery. Palatal implants were the most popular choice (70.6%, 60), followed by mini-screws (22.4%, 19) and mini-plates on the infrazygomatic crests (7.0%, 6). The preferred site of TAD insertion showed more variation in sagittal than in transversal dimension, and the median size of mini-screws used was 10.0-mm long (interquartile range (IQR) 2.3 mm) and 2.0-mm wide (IQR 0.3 mm).
Distalization against palatal implants and then distalization against mini-screws were the most popular treatment plans. Preferred site for TAD insertion varied depending on type and size but varied more widely in the sagittal than in the transversal dimension.
"The possible regions of the hard palate are in the mid-sagittal plane (Triaca et al., 1992; Wehrbein et al., 1996; Stockmann et al., 2009) or at paramedian locations (Bernhart et al., 2000, 2001). The median-sagittal area may be characterized by relatively low vertical bone support, so the paramedian region is a good alternative to place the palatal implants (Bernhart et al., 2000; Alsamak et al., 2012). "
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