Evaluation of mandibular cortical bone thickness for placement of temporary anchorage devices (TADs)

Effect of micro-osteoperforations (MOPs) on the rate of en masse orthodontic tooth retraction : A randomized controlled trial

PURPOSE

To evaluate the effect of micro-osteoperforations (MOPs) on the rate of orthodontic tooth movement (OTM) during en masse anterior retraction.

MATERIALS AND METHODS

Twenty patients were randomly allocated into experimental and control group of 10 each. In the control group, en masse retraction was performed with sliding mechanics with a coil spring. In the experimental group after alignment and levelling, MOPs were performed mesially and distally to all six anterior teeth in the interdental cortical region on the labial aspect of both arches. MOPs were performed at the beginning of space closure (T0) and 1 month after beginning of space closure (T1). En masse retraction was performed with sliding mechanics with a coil spring. Measurements were recorded on digital models made from scanned plaster casts at the beginning of space closure (T0) and monthly at each follow-up visit for the next 4 months (T1, T2, T3, T4). The monthly rate of OTM, the overall rate of OTM, and the difference between OTM in the MOP period (T0-T2) and post-MOP (T2-T4) period in the experimental and control group were evaluated. A visual analogue scale (VAS) was used to evaluate patients' pain experience.

RESULTS

The overall rate of OTM was significantly greater in the experimental group for both arches in the MOP period (T0-T2) and also in the post-MOP period (T2-T4) as compared to the control group. Within the experimental group, the rate of OTM in the MOP period was significantly greater than in the post-MOP period, which in turn was greater than that of the control group. The patients reported only mild discomfort for 24 h after performing the MOPs, which then gradually decreased.

CONCLUSIONS

The use of MOPs is effective in increasing the rate of en masse tooth retraction in both the maxillary and the mandibular arch. The rate of tooth movement was greater even in the post-MOP period as compared to the control group.

The Use of CAD/CAM Technology in Mandibular Canine Disimpaction: A Case Report

This case report of an 11-year-old subject shows the digital workflow for the management of an impacted mandibular canine using Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) technology along with Temporary Anchorage Devices (TADs). The miniscrew insertion site was planned using software, and a surgical guide was digitally designed and 3D printed. Orthodontic traction was performed using a 3D-designed and -printed device. In a single sitting, the miniscrew was inserted and the disimpaction device was also delivered. The primary objective of recovery and the repositioning of the impacted mandibular canine in the axis with its eruptive path was achieved. The space available and the subject's early stage of mixed dentition was considered favourable to a spontaneous eruption. This case report shows how CAD/CAM digital technology, combined with 3D printing, enables the creation of a surgical guide to position the miniscrew and the customized devices used for mandibular canine disimpaction. CAD/CAM surgical guides can help clinicians to position TADs with more accuracy and predictability, ensuring high quality bone support offering primary stability. Although orthodontic traction is the most complex therapeutic choice to implement, with the aid of CAD/CAM technology it is possible to proceed with accurate and minimally invasive orthodontic traction in order to recover a mandibular canine.

Relevant factors of posterior mandible lingual plate perforation during immediate implant placement: a virtual implant placement study using CBCT

BACKGROUND

To explore the influence of cross-sectional type and morphological parameters at the mandibular molar sites on lingual plate perforation (LPP) during the immediate implant placement (IIP).

METHODS

181 implants were virtually placed in the mandibular molar sites on the cone beam computed tomography (CBCT). Each cross-section of the implantation site was divided into the Undercut (U)/Parallel (P)/Convex (C) types. Morphologically relevant parameters were measured on the cross-sections, including width of the upper end (Wb), width of the lower end (Wc), vertical height (V), angle between the natural crown axis and the alveolar bone axis (∠β), LC depth (LCD), LC height, and angle between the horizontal line and the line connecting the most prominent point and the most concave point of lingual plate (∠α). Besides, the distance from the end of the virtual implant and the lingual bone plate of the cross-section (D_IL) was calculated. Relationships between all the morphologically relevant parameters and the D_IL were further analyzed.

RESULTS

A total of 77 (42.5%) cross-sections were classified as U-type, which was the most common one, accounting for 63% of the second molar regions. All LPP cases and most of the nearly LPP (87.9%) cases occurred at the U-type cross-sections, and the relationship between the D_IL and the morphological parameters can be expressed by a multivariate linear equation.

CONCLUSIONS

The occurrence rate of U-type cross-sections in the second molar region was very high, and the risk of LPP should be considered during IIP. Except for the U-type, significant large LCD, small Wc, and large ∠β were the important relevant factors. CBCT and multivariate linear equations could help to assess the LPP risk and provide a reference for implant placement design pre-surgery.

Cone Beam CT Assessment of Bone Width of Upper and Lower Jaws for Dental Implant Placement: An Iraqi Study

Background

Implantology focuses on the measurement of bone thickness in both the lower and upper jaws. This study aimed to measure and compare alveolar bone thickness of the upper and lower jaws at single edentate sites and cortical bone thickness of their mesial and distal dentate sites.

Methods

Thickness of alveolar bone thickness was measured in 80 upper and 80 lower implant edentate sites and that of buccal and lingual cortical plates of their mesial and distal dentate sites using Cone beam CT. The bone thickness of the edentulous sites was recorded at 3 points (crestal bone, five mm from the crest, and ten mm from the crest), while the bone thickness of the dentate sites was determined at four points (crestal bone, midroot bone, mid of the alveolar bone housing, and apical portion).

Results

An increased amount of bone was measured from the crest to the apical portion of the dentate sites on the buccal and lingual sides of both jaws with a highly significant difference detected among all the tested points (P <  0.0001). No statistical difference was detected between the means of buccal bone width at the first 3 points, except at point 4 (the apical portion), where the mean of the lower jaw (3.35 ± 0.54) was significantly larger than that of the upper jaw (3.17 ± 0.55) (P = 0.04). Bone width measured in the edentulous sites showed a gradual increase from the crest to the apical portions in both jaws.

Conclusion

Bone thickness at the coronal levels is low and susceptible to resorption compared to the apical portions regardless of the dentate state.

Evaluation of Orthodontic Mini-Implant Placement in the Maxillary Anterior Alveolar Region in 15 Patients by Cone Beam Computed Tomography at a Single Center in South India

BACKGROUND In this study, we aimed to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region by cone beam computed tomography (CBCT) in 15 patients at a single center in South India. MATERIAL AND METHODS A total of 15 CBCT scans of orthodontic patients after completion of leveling and aligning stage were included. The thickness of labial alveolar bone, labio-palatal bone, and inter-radicular distance between the maxillary central incisors (U1-U1), maxillary central and lateral incisor (U1-U2), and maxillary lateral incisor and canine (U2-U3) at vertical levels 4 mm, 6 mm, and 8 mm above the interdental cementoenamel junction were measured. Descriptive statistics, ANOVA, and Tukey post hoc tests were done to assess the differences among the groups. An independent t test was done to analyze differences by sex. RESULTS The thickness of cortical bone in the labial region was higher in the U2-U3 site than in the U1-U1 site, at a height of 4 mm. Also, there was a significant difference between 4 mm and 8 mm heights in the U2-U3 region. No significant difference was noted in bone dimensions among men and women and in the labio-palatal bone thickness among the different sites. The inter-radicular distance was the highest between the U2-U3 site, while it was the lowest in the U1-U2 site. CONCLUSIONS The findings from this center showed that when CBCT was used to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region, the U2-U3 and U1-U1 locations at heights between 6 mm to 8 mm apical to the interdental cementoenamel junction were optimal for placement of the mini-implants.

Three-dimensional Analysis of Alveolar Bone With and Without Periodontitis

OBJECTIVE

The aim of this study was to investigate the alveolar bone density and thickness in Chinese participants with and without periodontitis.

METHODOLOGY

This study was retrospective and cross-sectional in nature and used cone-beam computed tomography (CBCT) to evaluate alveolar bone loss, bone density, and bone thickness around 668 mandibular molars (344 periodontally healthy teeth and 324 teeth with periodontitis). Comparative statistical tests were done related to the age, sex, tooth type, tooth side, and degree of bone loss. The significance level was set to be P < .05.

RESULTS

The alveolar bone density significantly differed between the healthy and periodontitis groups (mean difference = 24.4 Hounsfield units; P = .007). Similarly, the alveolar bone thickness of the healthy group was significantly higher than that of the periodontitis group (4.6 ± 1.8 mm compared to 4.2 ± 1.1 mm). Teeth in females demonstrated a significantly (P ˂ .001) higher bone density compared with males in both healthy and compromised groups. However, males showed a significantly (P ˂ .05) thicker bone of the teeth than females in relation to the healthy group. The alveolar bone density and thickness in both healthy and periodontitis groups significantly differed between the first and the second molars (P < .001). The alveolar bone thickness had a highly significant difference (P < .001) between the different degrees of bone loss.

CONCLUSIONS

Alveolar bone thickness and density were reduced at periodontally diseased teeth.

Interradicular sites and cortical bone thickness for miniscrew insertion: A systematic review with meta-analysis

INTRODUCTION

Safe zone maps are useful for the clinician to plan miniscrew insertion and possibly reduce radiation exposure. This study aimed to investigate the available evidence regarding the presence of sufficient interradicular space and adequate cortical bone thickness in patients with a complete permanent dentition, in the vestibular and palatal or lingual interradicular sites, mesial to the second molar.

METHODS

PubMed, Scopus, Web of Science, Cochrane Library, and OpenGrey databases were searched up to January 2019 for observational studies involving patients with fully erupted second molars that investigated the amount of interradicular space and/or the cortical thickness of the alveolar processes using 3-dimensional data sets. A custom tool was prepared and used to assess the risk of bias in individual studies. A meta-analysis was performed when at least 4 different studies evaluated 1 identical parameter homogeneously. Publication bias was assessed with the Egger linear regression test.

RESULTS

Twenty-seven observational articles were included in the qualitative synthesis. Only 11 articles were at low risk of bias. Fifteen articles were included in the meta-analysis. The results were graphically reported in "safe-zone" maps.

CONCLUSIONS

In the maxilla, the most suitable insertion sites are those from mesial to the first molar to distal to the first premolar, and between the canine and the lateral incisor, all at 6 mm from the cementoenamel junction. In those areas, the cortical bone has adequate thickness, not requiring predrilling. In the mandible, the preferable vestibular interradicular spaces are those between first and second molars and between first and second premolars, both at 5 mm from the cementoenamel junction, and predrilling is suggested in these areas.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42016042081.

The ideal insertion angle after immediate loading in Jeil, Storm, and Thunder miniscrews: A 3D-FEM study

OBJECTIVE

The miniscrew is effectively used to provide additional anchorage for orthodontic purposes. The aim of this study was to identify an optimal insertion angle for Jeil, Storm, and Thunder miniscrews on stress distribution at the bone miniscrew interface.

MATERIALS AND METHODS

To perform 3-dimensional finite element model analysis, a 3-dimensional model with a bone block was constructed with type D2 of bone quality, and with miniscrews of Storm, Thunder, Jeil, with the diameter of 2, 1.5. 1.6mm and length 15.9, 12.4, 14.4mm respectively. The miniscrews were inserted at 15° 30°, 45°, 60°, 75° and 90° to the bone surface. A simulated horizontal orthodontic force of 200 gram was applied to the centre of the miniscrews head in all models, and stress distribution and its magnitude were evaluated with a 3-dimensional finite element analysis program.

RESULTS

In the cancellous bone, minimum stress was found at placement angles of 90° for Jeil and Storm, which was 0.37 and 0.39MPa respectively, and 15° for Thunder, which was 0.85MPa. The maximum von Mises stresses in the cancellous bone for Jeil was at 60°, which was 0.92MPa, and for Thunder at 90°, which was 1.3MPa.

CONCLUSION

Each miniscrew has an ideal insertion angle, optimal insertion positions were found within 90° for Jeil and for Storm but 15° for Thunder. Clinical significance 3-dimensional finite element analysis confirmed that each miniscrew has an ideal insertion angle according to its characteristics.

Cone-beam computed tomography-based quantitative analysis of the thickness of mandibular alveolar bone in adult females with different vertical facial patterns

Objectives:

The objectives of the study were to investigate the relationship between the thicknesses of the mandibular alveolar bone in the incisor, canine, premolar, and molar areas in adult female patients with different vertical skeletal patterns using cone-beam computed tomography (CBCT).

Materials and Methods:

CBCT images of 50 adult female patients before orthodontic treatment were analyzed. Based on the mandibular plane angle, they were divided into three groups: Low, average, and high-angle. The thicknesses of the alveolar and cancellous bones of the mandible were measured at the apices of the incisor, canine, first premolar, and first molar on both sides.

Results:

The thicknesses of the alveolar and cancellous bones were significantly larger in the low-angle group than in the high-angle group in all areas. At the incisal and canine areas, the thicknesses of the alveolar and cancellous bones were significantly larger in the average angle group than in the high-angle group. In the canine and first premolar areas, the thickness of the alveolar bone was larger in the low-angle group than in the average angle group.

Conclusions:

Vertical facial pattern is a significant factor in the width of the mandibular alveolar bone, especially in the incisor and canine areas. For planning labiobuccal movement in mandibular canines and incisors, information about the mandibular morphology is thought to be important, particularly in high-angle cases.

Assessment of the cortical bone thickness by CT-scan and its association with orthodontic implant position in a young adult Eastern Mediterranean population: A cross sectional study

OBJECTIVE

This study was conducted to assess cortical bone thickness in the alveolar process of maxilla and mandible and to investigate its association with different orthodontic implant positions in Eastern Mediterranean young adults.

MATERIALS AND METHODS

Computed tomography images of 50 patients aged between 18-35 years were included. Buccal, palatal and lingual cortical bone thicknesses were measured at 2, 4, 6, and 8mm from cemento-enamel junction starting from the mesial side of the second molar to the contralateral side. Pearson correlation was used to assess the association between cortical bone thickness and proposed orthodontic implant positions at all inter-radicular sites (p<0.05).

RESULTS

The highest value of buccal cortical bone thickness was found mesial to the second molar in the maxilla and mandible for both genders. The value of palatal cortical bone thickness was found to be at the highest rate mesial to canine and first premolar in males and females respectively. On the other hand, the highest value of lingual cortical bone thickness was recorded to be mesial to the first molar in both genders. In addition to that, the buccal cortical bone thickness was significantly higher than palatal at the area mesial to the second molar at all four levels from the cemento-enamel junction. A significant correlation was found between cortical bone thickness and 2, 4, 6, and 8mm orthodontic implant levels in all inter-radicular sites. The values of correlation coefficients ranged from 0.280 to 0.674 in the maxillary arch and from 0.266 to 0.605 in the mandibular arch.

CONCLUSIONS

From this study, we can conclude that as the position of the orthodontic implant moved more posteriorly and apically more cortical bone thickness was expected to be found in both jaws. A significant correlation was found between cortical bone thickness and the site of the orthodontic implant. Cortical bone thickness and its relationship with implant position should be taken into consideration when attempts are made to insert the orthodontic implant.

Cone-beam computed tomography analysis of cemento-osseous dysplasia-induced changes in adjacent structures in a Brazilian population

OBJECTIVES

To describe the effects of cemento-osseous dysplasia (COD) on anatomical structures.

METHODS

CBCT scans were retrospectively selected from a database of individuals who attended an Oral Medicine service. Cases with a confirmed diagnosis of periapical, focal, or florid COD were included. Two oral and maxillofacial radiologists assessed the scans. Frequencies of the variables were described according to COD case, lesion areas, and teeth.

RESULTS

Sixty COD cases affected 244 areas and 426 teeth. Florid COD was the most common (n = 48). Cortical bone (buccal, lingual, palatine, or mandibular) (n = 42) and the maxillary sinus (n = 13) were the structures most frequently affected by displacement or perforation. Thinning (n = 80), expansion (n = 62), and perforation (n = 60) of the cortical bone were common effects. The median size of the lesions was 12 mm in the mesiodistal direction, 8 mm in the buccal-lingual/palatal direction, and 9 mm in the superior-inferior direction. Root resorption was observed in 18.1% of all teeth, while tooth displacement was uncommon (0.6%). All teeth affected by COD had a discontinuous lamina dura and non-uniformly visible periodontal ligament space.

CONCLUSIONS

CBCT images revealed that cortical bone, lamina dura, and periodontal ligament space were the structures most affected by COD and the effects of COD on anatomical structures were more frequent than previously described.

CLINICAL RELEVANCE

CODs are fibro-osseous lesions common in the clinical practice, and relationship with anatomical structures is poorly described. CBCT is an appropriate method for the diagnosis and follow-up of patients with COD.

Quantitative CBCT evaluation of maxillary and mandibular cortical bone thickness and density variability for orthodontic miniplate placement

OBJECTIVE

To assess whether cortical bone thickness and density vary in relation to age, sex and skeletal pattern at the maxillary and mandibular areas suitable for miniplates placement for orthodontic purposes.

MATERIALS AND METHODS

CBCT of 92 subjects (42 males and 50 females) with skeletal class I, II or III malocclusion, divided between adolescents and adults, were examined. InVivoDental^® software (Anatomage Inc, USA) was used to measure 34 maxillary areas and 40 mandibular areas per side. Values obtained were then compared between the groups of subjects. Statistical analysis was performed using the non-parametric Wilcoxon-Mann-Whitney rank-sum test for independent samples.

RESULTS

No significant differences were found in the cortical bone thickness values between the three skeletal patterns, and according to sex and age. Both maxilla and mandible showed an increase in cortical bone thickness from the anterior towards the posterior regions, and from the alveolar boneto the basal bone. Cortical bone density significantly varied in relation to the subject's age, with adults always showing higher values. Slight clinically significant differences were found between the three skeletal patterns and sex.

CONCLUSION

In terms of cortical bone thickness, age, sex and skeletal pattern do not represent valid decision criteria for the evaluation of the best insertion areas for miniplates, while in terms of cortical bone density, only age is useful as a decision criterion.

Stress distributions in peri-miniscrew areas from cylindrical and tapered miniscrews inserted at different angles

Objective

The purpose of this study was to analyze stress distributions in the roots, periodontal ligaments (PDLs), and bones around cylindrical and tapered miniscrews inserted at different angles using a finite element analysis.

Methods

We created a three-dimensional (3D) maxilla model of a dentition with extracted first premolars and used 2 types of miniscrews (tapered and cylindrical) with 1.45-mm diameters and 8-mm lengths. The miniscrews were inserted at 30°, 60°, and 90° angles with respect to the bone surface. A simulated horizontal orthodontic force of 2 N was applied to the miniscrew heads. Then, the stress distributions, magnitudes during miniscrew placement, and force applications were analyzed with a 3D finite element analysis.

Results

Stresses were primarily absorbed by cortical bone. Moreover, very little stress was transmitted to the roots, PDLs, and cancellous bone. During cylindrical miniscrew insertion, the maximum von Mises stress increased as insertion angle decreased. Tapered miniscrews exhibited greater maximum von Mises stress than cylindrical miniscrews. During force application, maximum von Mises stresses increased in both groups as insertion angles decreased.

Conclusions

For both cylindrical and tapered miniscrew designs, placement as perpendicular to the bone surface as possible is recommended to reduce stress in the surrounding bone.

COMPARATIVE EVALUATION OF THE MECHANICAL PROPERTIES OF RESORBABLE AND TITANIUM MINIPLATES USED FOR FIXATION OF MANDIBULAR CONDYLE FRACTURES

In this paper, comparative evaluation of the mechanical properties of resorbable and titanium miniplates, which are used for the fixation of the mandibular condyle fractures, was carried out using finite element analysis (FEA). To do so, first two-dimensional (2D) computed tomography (CT) images of mandibles recorded from 10 adult patients were converted into three-dimensional (3D) solid body models. Then these models were transferred to the finite element software. In the finite element stage of the study, a condyle fracture was created onto the mandible and double-titanium and double-resorbable miniplates were separately fixed to the mandible surface such that the fractured sites to be firmly attached. Stress distribution over the plates and interfragmentary displacements between adjacent surfaces, which stem from the clenching force applying to the mandible, were calculated using FEA. It was observed from the results that maximum tensile stresses occurred in the titanium miniplates were significantly higher than those obtained from resorbable miniplates (p < 0.01). Higher maximum displacements between fractured surfaces were observed in the case of resorbable plate systems (p < 0.01). Maximum stress and displacement values obtained from both titanium and resorbable plate systems were under clinically acceptable limits. According to results, resorbable plates showed a similar reliability with titanium miniplates in terms of withstanding various stress and strain deformations.

Gene profiling of bone around orthodontic mini-implants by RNA-sequencing analysis

This study aimed to evaluate the genes that were expressed in the healing bones around SLA-treated titanium orthodontic mini-implants in a beagle at early (1-week) and late (4-week) stages with RNA-sequencing (RNA-Seq). Samples from sites of surgical defects were used as controls. Total RNA was extracted from the tissue around the implants, and an RNA-Seq analysis was performed with Illumina TruSeq. In the 1-week group, genes in the gene ontology (GO) categories of cell growth and the extracellular matrix (ECM) were upregulated, while genes in the categories of the oxidation-reduction process, intermediate filaments, and structural molecule activity were downregulated. In the 4-week group, the genes upregulated included ECM binding, stem cell fate specification, and intramembranous ossification, while genes in the oxidation-reduction process category were downregulated. GO analysis revealed an upregulation of genes that were related to significant mechanisms, including those with roles in cell proliferation, the ECM, growth factors, and osteogenic-related pathways, which are associated with bone formation. From these results, implant-induced bone formation progressed considerably during the times examined in this study. The upregulation or downregulation of selected genes was confirmed with real-time reverse transcription polymerase chain reaction. The RNA-Seq strategy was useful for defining the biological responses to orthodontic mini-implants and identifying the specific genetic networks for targeted evaluations of successful peri-implant bone remodeling.

Interradicular trabecular bone density of the lateral maxilla for temporary anchorage devices--a histomorphometric study

OBJECTIVE

To analyze the interradicular trabecular bone density of the lateral maxilla regarding the insertion of temporary anchorage devices (TADs).

MATERIAL AND METHODS

The material consisted of tissue blocks of autopsy material from 20 subjects (17 male, 3 female, 16 - 63y). The specimens comprised the dentated alveolar bone of the lateral maxilla. The interradicular areas (IRA) from canine to distally of the second molar (IRA 3-4, 4-5, 5-6, 6-7, 7d) were histomorphometrically measured with respect to the hard tissue fraction of the trabecular bone (HTFTB, %) and statistically analyzed.

RESULTS

Histomorphometric measurements showed the following results: Mean HTFTB of IRA 3-4 was 44.08%, of IRA 4-5 31.07%, of IRA 5-6 33.96%, of IRA 6-7 36.33% and of IRA 7d 25.40%. Only the difference between the HTFTB of IRA 3-4 and the other IRAs was statistically significant (p < 0.05). Regarding the minimum and maximum HTFTB value of each IRA, there was a great amount of difference, especially for IRA 3-4: minimum HTFTB was 17.20% and maximum 67.03%.

CONCLUSION

Apart from the IRA between canine and first premolar, the HTFTB in the IRAs of the lateral maxilla have to be classified as low or even moderate. IRA 3-4 should also be considered cautious regarding its minimum values. Thus, it seems that the interradicular trabecular bone density of the lateral maxilla is unfavorable to achieve a good primary stability of TADs.

Miniscrews versus surgical archwires for intermaxillary fixation in adults after orthognathic surgery

Objective

We compared the skeletal and dental changes that resulted from the use of two methods of intermaxillary fixation (IMF)-miniscrews and surgical archwire-in 74 adult patients who had Class III malocclusion and were treated with the same orthognathic surgical procedure at a hospital in Korea.

Methods

All the patients underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy with rigid fixation. They were divided into two groups according to the type of IMF used-group 1 underwent surgical archwire fixation and group 2 underwent orthodontic miniscrew fixation. In a series of cephalograms for each patient, we compared vertical and horizontal tooth-position measurements: (a) immediately after surgery (T₀), (b) 3 months after surgery (T₁), and (c) 6 months after surgery (T₂). Cephalometric changes within each group were examined using one-way analysis of variance (ANOVA) while the independent samples t-test procedure was used to compare the two groups.

Results

After surgery, the maxillary incisors tended to be proclined in both groups although there were no significant differences. Incisor overbite increased significantly in both groups from T₀ to T₁, and the miniscrew group (group 2) showed slightly greater overbite than the archwire group (group 1).

Conclusions

This study suggest that the use of orthodontic miniscrews and orthodontic surgical archwire for IMF in adult patients results in similar skeletal and dental changes.

Modified titanium implant as a gateway to the human body: the implant mediated drug delivery system

The aim of this study was to investigate the efficacy of a proposed new implant mediated drug delivery system (IMDDS) in rabbits. The drug delivery system is applied through a modified titanium implant that is configured to be implanted into bone. The implant is hollow and has multiple microholes that can continuously deliver therapeutic agents into the systematic body. To examine the efficacy and feasibility of the IMDDS, we investigated the pharmacokinetic behavior of dexamethasone in plasma after a single dose was delivered via the modified implant placed in the rabbit tibia. After measuring the plasma concentration, the areas under the curve showed that the IMDDS provided a sustained release for a relatively long period. The result suggests that the IMDDS can deliver a sustained release of certain drug components with a high bioavailability. Accordingly, the IMDDS may provide the basis for a novel approach to treating patients with chronic diseases.

Three-dimensional evaluation of maxillary anterior alveolar bone for optimal placement of miniscrew implants

OBJECTIVE

This study aimed to propose clinical guidelines for placing miniscrew implants using the results obtained from 3-dimensional analysis of maxillary anterior interdental alveolar bone by cone-beam computed tomography (CBCT).

METHODS

By using CBCT data from 52 adult patients (17 men and 35 women; mean age, 27.9 years), alveolar bone were measured in 3 regions: between the maxillary central incisors (U1-U1), between the maxillary central incisor and maxillary lateral incisor (U1-U2), and between the maxillary lateral incisor and the canine (U2-U3). Cortical bone thickness, labio-palatal thickness, and interdental root distance were measured at 4 mm, 6 mm, and 8 mm apical to the interdental cementoenamel junction (ICEJ).

RESULTS

The cortical bone thickness significantly increased from the U1-U1 region to the U2-U3 region (p < 0.05). The labio-palatal thickness was significantly less in the U1-U1 region (p < 0.05), and the interdental root distance was significantly less in the U1-U2 region (p < 0.05).

CONCLUSIONS

The results of this study suggest that the interdental root regions U2-U3 and U1-U1 are the best sites for placing miniscrew implants into maxillary anterior alveolar bone.