Placement Of Orthodontic Mini-implants Research Articles

Accuracy of fully guided orthodontic mini-implant placement evaluated by cone-beam computed tomography: a study involving human cadaver heads

ObjectivesThe aim of this study was to evaluate the accuracy of fully guided orthodontic mini-implant (OMI) placements supported by tooth- (TBGs) or gingiva-borne silicone guides (GBGs) based on virtually superimposed lateral cephalograms on virtual plaster models.Materials and methodsLateral cephalograms and corresponding plaster models were virtually superimposed for the planning of OMI positions; fully guided TBGs and GBGs were fabricated (each, n = 10). A total of 40 OMIs were inserted in a paramedian position into the palate of 20 human cadavers. Postoperative cone-beam computer tomographies (CBCTs) were carried out, and an accuracy evaluation was performed by comparing preoperative planning models and postoperative CBCTs. Deviations of the axis, tip, centre of the shoulder and vertical position of each of the implants were evaluated. Furthermore, the transfer accuracy measured by postoperative CBCT scans were compared with the accuracy determined using an intraoral scanner.ResultsA significant deviation between TBGs (2.81° SD 2.69) and GBGs (6.22° SD 4.26) regarding implant angulation was evaluated (p = 0.005). Implant tip and implant shoulder deviations revealed no statistical differences between the guides. Accuracy values of oral scans regarding vertical deviations were significantly more inaccurate when compared with CBCTs (p < 0.001).ConclusionsThe accuracy of an OMI position can be significantly increased by using a guide extension over the teeth. Vertical implant positions presented the lowest deviations. Postoperative oral scans and CBCTs represent diverging accuracy measurements when compared with virtual planning.Clinical relevanceUsers must keep in mind that despite virtual planning deviations, inaccuracies of a few millimetres may occur.

Measurement of buccal cortical plate thickness in the mandible of dentate adults in an Iranian population using cone-beam computed tomography

Objectives: This study aimed to measure the buccal cortical plate thickness in the mandible of dentate adults in an Iranian population using cone-beam computed tomography (CBCT). Materials and Methods: Eighty CBCT images were evaluated in this study using NNT Viewer 6.0 software. Images had high-resolution and had been taken by NewTom CBCT scanner with 11 x 8cm field of view. Measurements were made using the digital ruler of the software with 0.1mm accuracy. All analyses were performed by two observers: an oral and maxillofacial radiologist and a general dentist. In case of disagreement between the observers, measurements were repeated and the mean value was used for analysis. Data were analyzed by using linear regression. Results: The results showed that the thickness of buccal cortical plate increased from the canine towards the second molar site. The second molar site had the greatest density and thickness. Gender had a significant effect on the thickness of buccal cortical plate (P&lt;0.05) but the effect of right/ left quadrant was not significant (P&gt;0.05). The effect of age on this thickness was insignificant in some (P&gt;0.05) and significant (P&lt;0.05) in some other areas such that by an increase in age of patients, this thickness decreased (i.e. at the apex of canine, second premolar and second molar teeth). Conclusion: The buccal cortical plate thickness of the mandible increases from the anterior towards the posterior region, and the second molar area has the greatest thickness and density suitable for placement of orthodontic mini-implants or harvesting autogenous grafts.

Influence of age and gender in the assessment of inter-radicular and cortical bone thickness of the anterior maxilla and mandible for the placement of orthodontic mini-implants by cone-beam computed tomography: A retrospective study

Aim: To evaluate the cortical bone thickness in the anterior maxilla and mandible for the placement of orthodontic mini-implant in different age and gender using cone-beam computed tomography (CBCT). Objectives: To determine whether the studied anatomic measurements vary with age and gender of the patients and to determine the optimal sites for mini-implant placement by measuring inter-radicular and cortical bone thickness in the anterior maxilla and mandible. Materials and Methods: CBCT images of 120 (60 males and 60 females) patients were divided into three age groups (15–20, 21–30, and 31–40 years). Measurements were done for each inter-radicular space in the anterior maxilla and mandible at four different depths, i.e., at a distance from cementoenamel junction (CEJ) up to 3, 5, 7, and 9 mm apical to CEJ. The mesiodistal (MD), buccolingual (BL), Palartal cortical (PC), Lingual Cortical (LC) bone thickness was measured. Results: The mean measurement of MD, BL and buccal cortical (BC), and PC/LC cortical bone thickness on both sides of the maxilla at 9 mm is highest at distal to 13 and 23; in the mandible, it is highest between 42 and 43, 32 and 33. BL width at 3, 5, 7, and 9 mm is significantly highest in the maxilla in males. In mandible BL, width at 3 mm was significantly highest in males. PC thickness at 3mm (1.856±0.789) and BC (1.214 ±0.224 ), PC (2.226 ±2.114) thickness at 9mm bone level in maxilla was significantly highest at 31-40 years. Conclusion: There is an influence of age and gender on inter-radicular and cortical bone thickness of the anterior maxilla and mandible for the placement of orthodontic mini-implants.

Evaluation of stress pattern in periodontium and change in inclination during en masse retraction: Finite element analysis

ObjectiveUnderstanding the effects of retraction accompanied by intrusion on the periodontium of the anterior teeth along with the change in displacement during the en masse retraction of the maxillary anteriors using orthodontic mini-implants (OMIs) and retraction hooks at different levels. DesignFinite element analysis. Materials and methodThe finite element model of maxillary dentition was made using a computed tomographic scan. The implants of 1.5 × 8.0-mm dimensions were inserted at an angle of 90° at distance of 7 mm (low OMI) and10 mm (high OMI) with anterior retraction hooks (ARH) at 3, 6, and 9 mm. Six models were constructed for the study. After the boundary conditions were defined, 200 g of retractive force was applied from ARH at low and high OMI traction. The stresses on periodontal ligament (PDL), bone, bone surrounding implant, and cementum, along with change in inclination and displacements of anterior and posterior teeth along the y- and z-axis were determined. ResultsAn overall tipping and extrusion was seen in all the cases. Low OMI placement with retraction hooks at 3 mm and 6 mm showed more tipping movements, whereas high OMI with 9-mm ARH showed more bodily movement. Both high and low OMI with 9-mm ARH showed more root movement. The stresses in PDL, bone, and cementum were less at 3-mm ARH in both low and high OMI groups. The stresses were more in cortical bone than cancellous bone and also more on lateral incisors than central incisors. ConclusionIf controlled lingual tipping of anterior teeth is required with minimum torque loss, high OMI with low ARH is recommended, whereas if lingual root movements with retraction is required, high OMI and high ARH is recommended.

Evaluation of palatal support tissues for placement of orthodontic mini-implants in mouth breathers with high-narrow palates versus nose breathers with normal palates: a retrospective study.

The aim of this study was to compare the palatal total support tissues (TSTs) and bone support tissues (BSTs) at 5-mm paramedian section to the midsagittal suture between mouth breathers with high-narrow palates and nose breathers with normal palates and confirm the practicability and limitation on superimposition of lateral cephalograms and plaster models for orthodontic mini-implant (OMI) implantation in these patients. The sample consisted of 27 mouth breathers with high-narrow palates (study group (SG)) and 27 nose breathers with normal palates (control group (CG)). Upper digital dental models were superimposed with corresponding cone beam computed tomography (CBCT) images; then, TSTs and BSTs vertical to the curvature of the palatal mucosa were measured on the 5-mm paramedian section to the midsagittal suture. The measuring sites were the third ruga (R) and the sites anterior and posterior to R at 2-mm interval (A2, A4, A6, and A8; P2, P4, P6, and P8) along the palatal mucosa outline. TSTs and BSTs were also measured on the superimposition of lateral cephalograms and plaster models, and the site with the largest TST value in each patient was recorded. Descriptive statistics, independent-samples t test, and hierarchical clustering heat map were used for statistical analysis. The greatest average values of TSTs and BSTs in SG were 12.24 ± 2.63mm and 9.59 ± 2.36mm at P2 site, and those in CG were 12.96 ± 2.39mm and 10.56 ± 2.38mm at R site, respectively. The average values of both TSTs and BSTs in SG were less than those in CG at all insertion sites. Significant differences (P < 0.05) were found at A4, A6, and R for TSTs and at R and P4 for BSTs. P2 and R were clustered together for both TSTs and BSTs by the cluster analysis on heat map in both SG and CG. In both groups, only one patient from SG was found to have the insertion site with the largest TST value on 2D superimposition located in the blue area on the heat map, where the measurement values of TSTs were less than 8.5mm and those of BSTs were less than 5mm. Mouth breathers with high-narrow palates may have less palatal support tissues than nose breathers with normal palates at 5-mm paramedian section to the midsagittal suture of palate. The site a little posterior to R is more suitable for OMI implantation in mouth breathers. Two-dimensional superimposition of lateral cephalograms and plaster models can provide relatively effective assessment for the site choice of OMI implantation in both mouth breathers with high-narrow palates and nose breathers with normal palates. Three-dimensional superimposition of CBCT data and digital dental model can provide accurate information for palatal OMI implantation. Meanwhile, 2D superimposition of lateral cephalograms and plaster models can be used for assessing the implantation sites at 5-mm paramedian section to the midsagittal suture of palates in mouth breathers under most conditions even those who have less palatal support tissues.

CAD-CAM–fabricated mini-implant insertion guides for the delivery of a distalization appliance in a single appointment

This article reports on the technical aspects of using a computer-aided design-computer-aided manufacturing (CAD-CAM) insertion guide for the placement of orthodontic mini-implants used for the purpose of providing anchorage support for maxillary molar distalization. A 10-year-old girl presented with a bilateral full-step Angle Class II molar relationship in the permanent dentition, with anterior arch-length insufficiency and blocked out maxillary canine teeth. The primary treatment objective was to provide an esthetic and functional occlusal outcome, and secondarily to avoid the removal of multiple premolar teeth. The patient was initially treated with an implant-supported distalization device, and the occlusion was subsequently detailed with preadjusted fixed orthodontic appliances. The CAD-CAM procedure facilitates the safe and precise insertion of mini-implants in the anterior palate, potentially broadening the scope of use of palatal mini-implants for less experienced clinicians. The illustrated protocol allows for the insertion of mini-implants and fitting of a prefabricated appliance in a single office appointment.

Accuracy of orthodontic mini-implants placed at the anterior palate by tooth-borne or gingiva-borne guide support: a cadaveric study.

The aim of this cadaveric study was to measure the transfer accuracy of orthodontic mini-implant placement at the anterior palate depending on tooth-borne or gingiva-borne guide support. Forty orthodontic mini-implants were placed paramedian in the anterior palate of 20 cadaver heads using tooth-borne (TBG) or gingiva-borne guides (GBG). Placement was planned after superimposition of lateral cephalograms and corresponding plaster models. After mini-implant placement, digital impressions were taken with scanbodies. For the measurement of both linear and angle deviations, virtual planning models and postoperative oral scans were compared using automatic surface registration based on an iterative closest point algorithm. Statistical differences between TBG and GBG were detected for lateral deviations 0.88mm (SD 0.46) versus 1.65mm (SD 1.03) (p = .004) and sagittal angular deviations 3.67° (SD 2.25) versus 6.46° (SD 5.5) (p = .043). No differences were found for vertical deviations 2.34mm (SD 0.74) versus 2.14mm (SD 0.73) (p = .40) and transverse angular deviations 3.60° (SD 2.89) versus 4.06° (SD 3.04) (p = .62). The use of surgical guides based on silicone provides sufficient control of orthodontic mini-implant placement and is comparable to CAD/CAM templates. However, when compared with guided dental implantology, the planned mini-implant position is more inaccurate. However, accuracy can be significantly increased by guide extension involving the teeth. Clinical investigations have to prove if the accuracy is sufficient for receiving an orthodontic appliance. The use of lateral cephalograms and plaster models for silicone guide construction leads to lower radiation exposure and provides sufficient accuracy for palatal orthodontic mini-implant placement.

Bone and soft tissue palatal morphology and potential anchorage sides in cleft palate patients

AimThe aim of this study was to evaluate palatal vertical bone thickness and density in relation to soft tissue on the hard palate for better selection of adequate bone regions for the insertion of orthodontic mini-implants (MIs) in cleft palate patients. Materials and methodsCone beam computed tomography scans (CBCT) were obtained from 60 patients (mean age range 9–12). The study population included patients with isolate right side cleft palate formation (n = 20; 6 females; 14 males), left side cleft palate formation (n = 20; 9 females; 11 males) and without cleft formation as control group (n = 20; 15 females; 5 males). Bone and soft tissue measurements were performed vertical at a 90° angle to the bone surface, on previously defined measurement points (n = 88) on the hard palate. Bone density was measured on ten vertical layers in caudo-cranial direction. ResultsIn non-cleft patient the highest bone thickness was in the anterior palate and decreased significantly in posterior direction. In patients with right and left cleft palate, the highest vertical bone level could be observed at the palatal premaxillary border opposite to the cleft side. Patients in the control group showed a significantly lower vertical soft tissue thickness than patients with palatal cleft formation. The evaluation of bone density showed no significant differences in all three groups. ConclusionThe results suggest that the favorable region for orthodontic MI placement is in the similar anatomical region compared to non-cleft patients, but differs from one side in each group. In unilateral cleft palate patients, the highest bone level was found on the anterior palate side opposite to the cleft side, indicating the most effective region for MIs placement.

The measurement of buccal cortical bone thickness with CT images in jaw deformity patients undergoing orthodontic mini‐implants

Background Recently, placement of orthodontic mini-implants (anchor screws) is widely used in orthodontic treatment. One of the anatomical factors affecting the stability of the anchor screws is the bone characteristics (shape, bone mineral density, cortical bone thickness). It is necessary to understand anatomical factors in the area of placement with preoperative diagnostic imaging. Aim/Hypothesis In this study, we measured and evaluated the buccal cortical thickness of the mesio-distal interdental space at the mandibular first molar with multi-detector low computed tomography (MDCT) images of jaw deformity patients. Material and Methods MDCT images of 28 jaw deformity patients participating in the study were acquired and used for the preoperative planning of sagittal split ramus osteotomy (SSRO) surgery. All patients had been previously diagnosed as having an Angle class III malocclusion. After acquisition of MDCT data, all data were transferred to a workstation and evaluated using Zio Cube software (Ziosoft, Inc, Tokyo). The standard plane of all MDCT data was set at the occlusal plane. The cortical thickness on the mesial and distal part of the first molar were measured on the reconstructed cross-sectional images at the level of 5 and 10 mm inferior to the cement-enamel junction (CEJ) on each mesial and distal side. On the same images, the inclination of the mandibular bone was also recorded. The MDCT images were excluded from this study if- (1) Pathological findings were seen in the posterior mandible, and (2) The images were found to exhibit insufficient image quality due to metal artifacts from acquisition. Results Initially, all MDCT images were screened. From these, 5 were excluded according to the exclusion criteria. Thus, a total of 46 sides from 23 patients were used in the analysis. The 23 patients consisted of 15 females and 8 males with a mean age of 22.9 years (range from 18–33 years). The average thickness at the 5 and 10 mm level form the CEJ on the mesial portion of the first molar were 1.44 and 1.91 mm respectively, and on the distal portion were 1.80 and 2.68 mm respectively. Statistical differences were confirmed for buccal cortical thickness at 5 and 10 mm from the CEJ in both the mesial and distal portions of the mandibular first molar. The average lingual inclination of the mandible was by 80.5° n the mesial and 71.2° in the posterior portion. Conclusions and Clinical Implications A detailed understanding of the anatomical characteristics is absolutely critical in maxillofacial surgical procedures, including the placement of anchor screws. To reduce postoperative discomfort, the clinician should be aware of each patient's morphological characteristics.

Utility of CBCT for the measurement of palatal bone thickness

IntroductionThe palate is an alternative anchoring site for orthodontic implants. Adequate bone at mini-implant placement site can influence the success or failure of anchorage. Hence, it is imperative to measure the thickness of the palatal bone. Materials and methodsCBCT scans of 30 subjects in the age range of 12 to 28 years were retrospectively analyzed with the objective of measuring the palatal bone thickness. Thirty sites were identified on each CBCT scan with incisive foramen as a landmark and measurements were obtained anteroposteriorly as well as mediolaterally, using Carestream 3D imaging software. The data collected was analyzed using one-way ANOVA. ResultsStatistical analysis revealed higher palatal bone thickness at the median and paramedian regions of anterior palate, 4mm and 8mm distal to incisive foramen. ConclusionCBCT is an ideal modality for measuring palatal bone thickness and can be utilized for locating the ideal site for placement of orthodontic mini-implants.

Anatomic landmarks and availability of bone for placement of orthodontic mini-implants for normal and short maxillary body lengths.

Increasing numbers of orthodontic mini-implants are placed in the anterior maxilla. To our knowledge, bone levels and root proximity of patients with cephalometrically short maxillae have not been investigated before. The first, second, and third rugae were used as clinical reference lines, and the aim of this study was to measure bone availability in that area by comparing patients with short and normal maxillary body lengths. The sample consisted of 21 patients in each group: short maxillary body length and normal maxillary body length. The patients' study models were bisected, and the outline of the palatal contour was marked on the surface. The models were scanned, and the palatal contours were superimposed on the palatal structures of their respective initial cephalometric headfilms, and the vertical and oblique bone levels of the sagittal plane were compared using the Student t test. The level of significance was set at P<0.05. Compared with maxillae of normal maxillary body length, less bone was available in maxillae of short maxillary body length. However, the differences did not reach clinical or statistical significance (P>0.05) at the third rugae. Almost equivalent average bone depth at the third rugae in patients with normal and short maxillary body lengths suggests that this site can be used for 8-mm long obliquely inserted orthodontic mini-implants.

Quantitative evaluation of maxillary alveolar cortical bone thickness and density using computed tomography imaging.

Primary stability is essential to the success of orthodontic mini-implants (OMIs) and heavily depends on the mechanical retention between OMIs and their supporting bone. Alveolar cortical bone commonly serves as the supporting bone for OMIs during treatment. The purposes of this study were to characterize alveolar cortical bone thickness and density in the maxilla and to explore patient factors that may significantly affect these bone properties. Sixty medical computed tomography scans of the maxilla were analyzed from a selected sample of patients seen at the Radiology Department of Boston Children's Hospital. Interradicular alveolarbone thickness and density were measured at 2, 4, 6, and 8mm from the buccal and palatal alveolar bone crests using the Synapse 3D software (version 4.1; FUJIFILM Medical Systems USA, Stamford, Conn). Analyses were conducted with STATA /1C (version 12.0 for Windows; StataCorp, College Station, Tex) using multivariate mixed-effects regression models and paired t tests. Mean age and body mass index of the study sample were 17.88years and 22.94kg/m2, respectively. Cortical bone density and thickness significantly increased from the coronal (2mm) to the apical (8mm) regions of the alveolar bone (P<0.05). At 8mm from the alveolar crest, interradicular buccal cortical bone was thickest (1mm) and densest (1395 Hounsfield units) between the first and secondmolars. On the palatal side, the thickest bone (1.15mm) was found between the canine and first premolar; it was similarly densest (1406 Hounsfield units) between the first premolar and canine, and between the first premolar and second premolar interradicular bones. On average, palatal cortical bone was thicker and denser compared with buccal; this difference was statistically significant (P<0.01) in the anterior and middle maxilla, with the anterior maxillary region showing the greatest difference. Female subjects have significantly denser bone compared with male subjects; however, sex is not significantly associated with bone thickness. Body mass index and age are positively associated with bone thickness and density. Radiologic absence of bone was more commonly seen in the anterior maxilla. Alveolar bone properties vary in the maxilla in patterns that could guide clinicians in selecting sites best suited for placement of OMIs.

Relationship Between the Thickness of Cortical Bone at Maxillary Mid-palatal Area and Facial Height Using CBCT.

Introduction : Orthodontic mini-implants have been incorporated into orthodontic treatment modalities. Adequate bone at mini-implant placement site can influence the success or failure of anchorage. The present study was to determine the thickness of cortical bone in the maxillary mid-palatal area at predetermined points for the placement of orthodontic mini-implants using Cone Beam CT technique in order to evaluate the relationship of these values with the facial height. Materials and Methods : A total of 161 patients, consisting of 63 males (39.13%) and 98 females (60.87%), were evaluated in the present study; 38% of the subjects had normal facial height, 29% had short face and 33% had long face. In order to determine which patient belongs to which facial height category, i.e. normal, long or short, two angular and linear evaluations were used: the angle between S-N and Go-Me lines and the S-Go/N-Me ratio. Twenty points were evaluated in all the samples. First the incisive foramen was located. The paracoronal cross-sections were prepared at distances of 4, 8, 16 and 24 mm from the distal wall of the incisive foramen and on each cross-section the mid-sagittal and para-sagittal areas were determined bilaterally at 3- and 6-mm distances (a total of 5 points). The thicknesses of the cortical plate of bone were determined at the predetermined points. Results : There was a significant relationship between the mean cortical bone thickness and facial height (p<0.01), with significantly less thickness in long faces compared to short faces. However, the thickness of cortical bone in normal faces was similar to that in long and short faces. Separate evaluation of the points showed that at point a16 subjects with short faces had thicker cortical bone compared to subjects with long and normal faces. At point b8 in long faces, the thickness of the cortical bone was significantly less than that in short and normal faces. At point d8, the thickness of the cortical bone in subjects with short faces was significantly higher than that in subjects with long faces. Conclusion : At the point a16 the cortical bone thickness in short faces was significantly higher than normal and long faces. The lower thickness of the cortical bone in the palatal area at points b8 and d8 in subjects with long faces might indicate a lower anchorage value of these points in these subjects.

Quantitative evaluation of maxillary interradicular bone with cone-beam computed tomography for bicortical placement of orthodontic mini-implants

The purpose of this study was to propose a protocol for safe bicortical placement of mini-implants by measuring the interradicular spaces of the maxillary teeth and the bone quality. Cone-beam computed tomography data were obtained from 50 adults. Three-dimensional reconstructions and measurements were made with SimplantPro software (Materialise, Leuven, Belgium). For each interradicular site, the bone thicknesses and interradicular distances at the planes 1.5, 3, 6, and 9 mm above the cementoenamel junction were measured. Standard bone units were defined to evaluate the influences of bone density and the different placement patterns on the stability of the mini-implants. The safe interradicular sites in the maxilla for bicortical placement of 1.5-mm-diameter mini-implants were in all planes between the first and second premolars, and between the second premolar and the first molar. The safe palatal sites were between the first and second molars, and the safe labial sites of the 9-mm plane were between the central incisors, and between the lateral incisor and the canine. The safe buccal sites of the 6- and 9-mm planes were between the first and second molars, and the safe buccal sites of the 3-, 6-, and 9-mm planes were between the canine and the first premolar. Most bone thicknesses were from 8 to 12 mm. The optimal placement angle between the second premolar and the first molar was 58°. Bicortical placement could have more standard bone units than unicortical placement in the maxilla. Bicortical placement would be more stable in the maxilla. For the site between the molars, special care should be taken at a plane higher than 6 mm to prevent maxillary sinus penetration. The most favorable interradicular area in the maxilla was between the second premolar and the first molar.

Maximum principal strain as a criterion for prediction of orthodontic mini-implants failure in subject-specific finite element models.

To investigate the most reliable stress or strain parameters in subject-specific finite element (FE) models to predict success or failure of orthodontic mini-implants (OMIs). Subject-specific FE analysis was applied to 28 OMIs used for anchorage. Each model was developed using two computed tomography data sets, the first taken before OMI placement and the second taken immediately after placement. Of the 28 OMIs, 6 failed during the first 5 months, and 22 were successful. The bone compartment was divided into four zones in the FE models, and peak stress and strain parameters were calculated for each. Logistic regression of the failure (vs success) of OMIs on the stress and strain parameters in the models was conducted to verify the ability of these parameters to predict OMI failure. Failure was significantly dependent on principal strain parameters rather than stress parameters. Peak maximum principal strain in the bone 0.5 to 1 mm from the OMI surface was the best predictor of failure (R(2) = 0.8151). We propose the use of the maximum principal strain as a criterion for predicting OMI failure in FE models.

The most distal palatal ruga for placement of orthodontic mini-implants.

To evaluate the stability and bone availability of the most distal (third) palatal ruga, as an anatomical region for safe insertion of orthodontic mini-implants (OMIs) in the anterior palate. Orthodontic records of 35 patients were analysed. Initial (T1) and final (T2) study models were bisected and the outline of the palatal contour was marked on the surface. Models were scanned and the palatal contours were superimposed on the palatal structures on the respective initial and final cephalometric images. Cephalometric measurements were used to assess vertical (3rdRug-PP, 2ndRug-PP, and 1stRug-PP), and oblique bone levels (3rdRug-U1, 2ndRug-U1, 1stRug-U1, and 3rdRug-U1(o)). Paired Student's t-test was used to compare measurements between T1 and T2. The position of the third palatal ruga remained stable during orthodontic treatment (Δ2ndRug-3rdRug P = 0.1mm; P = 0.61 and Δ1stRug-3rdRug P = 0.2mm; P = 0.39). Bone availability also remained adequate (3rdRug-U1T2 (o) = 9.9mm). The third palatal ruga is a reliable clinical landmark to evaluate bone availability for the placement of OMIs in the anterior palate.

Hard and soft tissue considerations at mini-implant insertion sites.

Various factors influence where orthodontic mini-implants will be placed. This article highlights the pertinent variables that should find consideration when planning the placement of orthodontic mini-implants.

Positional Guidelines for Orthodontic Mini-implant Placement in the Anterior Alveolar Region: A Systematic Review

To investigate the adequacy of potential sites for insertion of orthodontic mini-implants (OMIs) in the anterior alveolar region (delimited by the first premolars) through a systematic review of studies that used computed tomography (CT) or cone beam CT (CBCT) to assess anatomical hard tissue parameters, such as bone thickness, available space, and bone density. MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews were searched to identify all relevant papers published between 1980 and September 2011. An extensive search strategy was performed that included the key words "computerized (computed) tomography" and "mini-implants." Information was extracted from the eligible articles for three anatomical areas: maxillary anterior buccal, maxillary anterior palatal, and mandibular anterior buccal. Quantitative data obtained for each anatomical variable under study were evaluated qualitatively with a scoring system. Of the 790 articles identified by the search, 8 were eligible to be included in the study. The most favorable area for OMI insertion in the anterior maxilla (buccally and palatally) and mandible is between the canine and the first premolar. The best alternative area in the maxilla (buccally) and the mandible is between the lateral incisor and the canine, while in the maxillary palatal area it is between the central incisors or between the lateral incisor and the canine. Although there is considerable heterogeneity among studies, there is a good level of agreement regarding the optimal site for OMI placement in the anterior region among investigations of anatomical hard tissue parameters based on CT or CBCT scans. In this context, the area between the lateral incisor and the first premolar is the most favorable. However, interroot distance seems to be a critical factor that should be evaluated carefully.

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis

ObjectiveTo examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction.MethodsFive finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth.ResultsWith regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction.ConclusionsThese results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs.

Assessment of potential orthodontic mini-implant insertion sites based on anatomical hard tissue parameters: a systematic review.

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. 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.