Evaluation of alveolar cortical bone thickness and density for orthodontic mini-implant placement

A cross-sectional study of the anatomy of the jaws of a central-European caucasian population using cone beam computer tomography as a prerequisite for designing pre-formed calcium phosphate cement scaffolds

PURPOSE

This study aims to measure the cortical and cancellous bone thickness in the upper and lower jaws, serving as a data template for developing pre-defined calcium phosphate cement primary implant forms. These measurements are crucial for creating a biphasic scaffold.

METHODS

Forty complete jaws were assessed for cortical bone shape and thickness using statistical analysis and specific software tools. Sex and age were considered, and four groups were created.

RESULTS

The cumulative thickness of the cortical layer varied from region to region. In both the upper and lower jaws, the cortical layer in the molar region was significantly thicker than in the frontal region. Within the alveolar process, cortical thickness increases with distance from the alveolar crest on both sides. The oral side of the lower jaw is significantly thicker than the vestibular side. For the upper jaw, no significant differences between the oral and vestibular sides were found in this study. Additionally, it is noteworthy that men have a significantly thicker cortical layer than women. Regarding age, no significant overall differences were found.

CONCLUSION

Mathematical analysis of anatomical forms using polynomial functions improves understanding of jaw anatomy. This approach facilitates the design of patient-specific scaffold structures, minimizing the need for costly and time-consuming planning and enabling more efficient implementation of optimal therapy.

How does arch form and interproximal contact size affect the 3D displacements and rotations of teeth: a finite element analysis

OBJECTIVE

The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF).

METHODS

Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar.

RESULTS

Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models.

CONCLUSIONS

Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.

Comparative analysis of anchorage strength and histomorphometric changes after implantation of miniscrews in adults and adolescents: an experimental study in Beagles

OBJECTIVES

This study aimed to explore the differences in anchorage strength and histomorphometric changes in orthodontic miniscrews between adult and adolescent beagles.

MATERIAL AND METHOD

Six adult beagles and six young beagles were used as experimental subjects, and eight miniscrews were symmetrically placed in the posterior mandible of each dog. Measurement of the displacement (mm) of two adjacent miniscrews after load application was performed to compare the anchorage strength between the adult and adolescent groups. Three intravital bone fluorochromes (oxytetracycline, calcein green, xylenol orange) were administered postoperatively to mark the active bone-forming surface. Subsequently, the mineral apposition rate and bone-implant contact ratio were measured for dynamic and static histomorphometry. Finally, the expression levels of the RANKL/OPG ratio were evaluated by immunohistochemistry.

RESULTS

The average displacement of miniscrews in the adult group was significantly less than that in the adolescent group after load application. For histomorphometry analysis, the mineral exposure rate in the adolescent group was higher than that in the adult group with or without force application. In addition, more fractures and new bone formation but deceased bone-implant contact ratios were observed in the adolescent group than in the adult group. The ratio of RANKL/OPG expression increased more in the adolescent group than in the adult group.

CONCLUSION

Miniscrews do not remain in the same position as skeletal anchors, and the amount of displacement was higher in adolescent group than that in adult group, reflecting the weaker anchorage strength of miniscrews in adolescents due to the higher bone turnover rate and active bone remodelling. Therefore, it is feasible to apply orthodontic loading to the miniscrews in adult patients earlier, even immediately, but it is recommended to wait a period for the adolescents.

Temporary anchorage devices in orthodontics: a bibliometric analysis of the 50 most-cited articles from 2012 to 2022

OBJECTIVES

To identify and analyze the 50 most cited articles on temporary anchorage devices (TADs) and investigate the achievement and development of scientific research about the topic through a bibliometric analysis.

MATERIALS AND METHODS

On August 22, 2022, a computerized database search was performed to detect papers published in the scientific literature about TADs from 2012 to 2022. Metrics data were identified using the Incites Journal Citation Reports (Clarivate Analytics) data set. The Scopus database was used to obtain information on the authors' affiliations, country of origin, and h-index. Key words were automatically harvested from the selected articles to implement the visualized analysis.

RESULTS

From a total of 1858 papers screened by searching the database, a list of the top 50 most cited articles was created. The total number of citations collected by the 50 most cited articles in TADs was 2380. Among the 50 most cited articles on TADs, 38 were original research papers (76.0%) and 12 were reviews (24.0%). As shown by the key word-network analysis, Orthodontic anchorage procedure was identified as the larger node.

CONCLUSIONS

Findings of this bibliometric study showed an increasing number of citations for papers on TADs, accompanied by a simultaneous rise in scientific interest in this topic in the past decade. The present work identifies the most influential articles, emphasizing the journals, the authors, and the topics addressed.

Evaluation of trabecular bone and mandibular cortical thickness in adults with different vertical facial types

OBJECTIVES

This study investigated differences in trabecular structure and mandibular cortical thickness in adults related to vertical facial type (VFT), sex, and their interactions.

STUDY DESIGN

Lateral cephalometric radiographs (LCRs) and panoramic radiographs (PRs) of 256 patients were reviewed. The VFT classification into low-angle, normal, and high-angle groups was determined using angular and linear measurements on LCRs. Fractal dimension (FD) values and mandibular radiomorphometric indices (RMIs) were calculated on PRs.

RESULTS

Two-way analysis of variance revealed significant differences in FD overall among VFT groups in all sites (P < .001), with pairwise comparisons indicating the greatest values in the high-angle group in the condyle (P < .05) but in the low-angle group elsewhere (P < .001). RMIs were significantly different overall regarding VFT only in the posterior mandible (P = .004), with pairwise comparisons revealing low-angle and normal group values greater than high-angle group values (P < .05). Patient sex and the interaction of facial type and sex had no significant effect on any bone measurements.

CONCLUSIONS

VFT had significant effects on trabecular structure at all measured sites, but cortical thickness was affected only in 1 location.

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.

Evaluation of Cortical Bone Thickness of Posterior Implant Sites Using CBCT in Iraqi Population

Background. Cortical bone thickness (CBT) is a critical factor for implant success and for determining the long-term dental implant treatment outcome. Objectives. The objective of this investigation was to examine posterior cortical bone thickness buccally and lingually in dentate and edentulous implant sites according to gender. Materials and Methods. CBT of 160 patients requiring a single posterior tooth implant was investigated by CBCT. The study included 80 males and 80 females. CBT was measured for implant edentulous sites at 3 levels including crestal bone (level 1), five mm from the crest (level 2), and ten mm from the crest (level 3). CBT was also measured for dentate sites at 3 levels including crestal bone (level 1), midroot bone (level 2), and apical portion (level 3). The differences of bone thickness between the levels of dentate sites were statistically analyzed using a Kruskal–Wallis one-way analysis of variance. Mann–Whitney test was used to determine the specific differences between group members. For the edentulous site, a one-way ANOVA was used. Results. CBT increased gradually from the crestal level to the apical level in all groups (buccal and lingual side, male and female). However, CBT at lingual side was statistically higher than that at buccal side in all groups. The mean value of CBT was significantly higher in males than females for both edentulous and dentate site. The dentate site shows a higher CBT in the apical level than the edentulous group in both male and female/buccal and lingual groups. Conclusion. CBT at the coronal levels is low and susceptible for resorption compared to the apical portion, especially for the female group. Moreover, CBT is thicker in males than females. It is essential to measure the CBT before making a treatment plan with dental implant prosthesis.

Thickness of the Buccal and Alveolar Bones Overlying Central Incisors: A Radiographic Iraqi Study

Background. Initial bone thickness has a substantial impact on the success of dental implant treatments. The objective of the current study was to analyze the thickness of the buccal and alveolar bone at the central incisors using CBCT in relation to gender and side to determine the anatomical features and choose the best implant treatment option for minimizing the surgical complications. Methods. One hundred CBCT images were investigated (50 females and 50 males, aged 20 to 50 years old). The buccal bone thickness and alveolar bone thickness were evaluated for right and left sides of each subject at three sites; C: crest (3 mm); M: middle (6 mm); A: apical (9 mm) from the cementoenamel junction. Results. The mean thickness of buccal bone was less than 2 mm on the incisors according to side and gender. Buccal bone thickness revealed a statistically significant difference between right and left sides at the apical point in both females and males with $p$ values of ( $p\le 0.001$ ) and (0.001), respectively. The buccal bone thickness displayed statistically significant differences between genders at all sites. The alveolar thickness demonstrated similar significant differences between genders except for the crest site. Conclusions. Iraqi participants had about 1 mm buccal bone thickness at 3 mm apical from the CEJ in right and left central incisors with a progressive rise in bone thickness to be less than 2 mm at the apex. Alveolar bone also showed the same increase in bone thickness from crest to apex. Bone thickness was greater in males than females. The present study provided valuable CBCT data on bone thickness of the esthetic maxillary region as a preoperative analysis for establishing an immediate implant treatment plan with aesthetically pleasing long-term outcomes.

Evaluation of Optimal Sites for the Insertion of Orthodontic Mini Implants at Mandibular Symphysis Region through Cone-Beam Computed Tomography

This study aims to evaluate the overall bone thickness (OBT) and cortical bone thickness (CBT) of mandibular symphysis and to determine the optimal sites for the insertion of orthodontic mini implants. Cone-beam computed tomography (CBCT) images of 32 patients were included in this study. The sample was further categorized into three facial types: low-, average-, and high-angle. OBT and CBT were measured at the mandibular symphysis region. All measurements were performed at six different heights from the cementoenamel junction [CEJ] and at seven different angles to the occlusal plane. Analysis of variance (ANOVA) was used for statistical comparison and a p value less than 0.05 was considered statistically significant. Our results revealed that neither OBT nor CBT was influenced by age or sex, except for the observation that CBT was significantly greater in adults than in adolescents. OBT and CBT were significantly greater in low-angle cases than in average- and high-angle cases. Both OBT and CBT were significantly influenced by insertion locations, heights and angles, and their interactions. CBT and OBT were greatest at the location between two lower central incisors, and became greater with increases in insertion height and angle. Both recommended and optimal insertion sites were mapped. The mandibular symphysis region was suitable for the placement of orthodontic mini implants. The optimal insertion site was 6–10 mm apical to the CEJ between two lower central incisors, with an insertion angle being 0–60 degrees to the occlusal plane.

Anesthetic efficacies of buccal with palatal injection versus buccal with intra-septal injection in permanent maxillary first molars of pediatric patients

The high success rate of dental treatment is dependent on the cooperation of pediatric patients during procedures. Dental treatment often causes pain, particularly in children. The factors in providing treatment to pediatric patients include the characteristics and location of the tooth, profoundness of the anesthesia including the type of local anesthetic, and cooperation of the patient. Previous studies have examined several techniques to successfully achieve profound pulpal anesthesia in maxillary permanent teeth. The dentist should select the injection technique to be used based on patient needs. In children, either buccal with palatal injections or buccal with intra-septal injections may be used to anesthetize the permanent maxillary first molar. Buccal with palatal injections are commonly used prior to routine maxillary dental procedures. Currently, there are only a few studies on the employment of buccal with intra-septal injections to anesthetize permanent maxillary first molars in pediatric patients. This review will focus on efficacy of buccal with palatal versus buccal with intra-septal pulpal anesthesia of the permanent maxillary first molars in pediatric patients and aim to determine which technique should be used during routine dental procedures.

Assessment of Maxillary Incisors' Angulation and Position in Different Types of Malocclusions Using Cone-Beam Computed Tomography

Background:

This study is aimed to assess the maxillary incisors' root position, angulation, and buccal alveolar bone thickness in both genders and different classes of malocclusion using cone-beam computed tomography (CBCT).

Materials and Methods:

Two hundred and six CBCT images were gathered and analyzed by three-dimensional On-Demand software to measure the variables of 803 maxillary central and lateral incisors. Genders and class difference was determined by unpaired t-test, one-way ANOVA, and Chi-square tests.

Results:

Buccal root position of the maxillary incisors accounted for in the majority of the cases followed by the middle and palatal positions. The thickness of alveolar bone appears to have nearly the same pattern of decreasing in the mean values above the level of 2 mm from the crest of the bone up to the 6 mm level then increase in the apex of the root. The angle between the long axis of the maxillary incisors and the corresponding alveolar bone is higher significantly in class II followed by class I and III with no significant gender difference.

Conclusions:

most of the maxillary incisors examined were located in a very close position to the buccal cortical plate and covered by a thin buccal bone wall. The apparent association was noted between the incisors' root position and angulation in the alveolar bone with the buccal bone thickness.

Quantitative cone-beam computed tomography evaluation of hard and soft tissue thicknesses in the midpalatal suture region to facilitate orthodontic mini-implant placement

Objective

To identify the most favorable sites that optimize the initial stability and survival rate of orthodontic mini-implants, this study measured hard and soft tissue thicknesses in the median and paramedian regions of the palate using cone-beam computed tomography (CBCT) and determined possible sexand age-related differences in these thicknesses.

Methods

The study sample comprised CBCT images of 189 healthy subjects. The sample was divided into four groups according to age. A grid area was set for the measurement of hard and soft tissue thicknesses in the palate. Vertical lines were marked at intervals of 0, 1.5, and 3.0 mm lateral to the midpalatal suture, while horizontal lines were marked at 2-mm intervals up to 24 mm from the posterior margin of the incisive foramen. Measurements were made at 65 points of intersection between the horizontal and vertical lines.

Results

The palatal hard tissue thickness decreased from the anterior to the posterior region, with a decrease in the medial-to-lateral direction in the middle and posterior regions. While the soft tissue was rather thick around the lateral aspects of the palatal arch, it formed a constant layer that was only 1-2-mm thick throughout the palate. Statistically significant differences were observed according to sex and age.

Conclusions

The anterolateral palate as well as the midpalatal suture seem to be the most favorable sites for insertion of orthodontic mini-implants. The thickness of the palate differed by age and sex; these differences should be considered while planning the placement of orthodontic mini-implants.

Influence of low-level-laser therapy on the stability of orthodontic mini-screw implants. A systematic review and meta-analysis

BACKGROUND

The influence of low-level-laser therapy (LLLT) on the stability of orthodontic mini-screw implants (MSIs) has not been systematically reviewed.

OBJECTIVES

The aim was to assess the influence of LLLT on the stability of orthodontic MSIs.

METHODS

An unrestricted search of indexed databases was performed.

SELECTION CRITERIA

Randomized controlled clinical trials (RCTs) investigating the influence of LLLT on orthodontic MSI stability.

DATA COLLECTION AND ANALYSIS

Two authors independently performed study retrieval and selection, and data extraction. The risk of bias (RoB) of individual studies was assessed using the Cochrane RoB Tool for RCTs. Meta-analyses were performed separately for RCTs using periotest and resonance frequency analysis (RFA) to measure MSI stability; and a random effects model was applied. Subgroup analyses were performed based on the time-points of MSI stability evaluation. The quality of available evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

Initially, 1332 articles were screened. Six RCTs with a split-mouth design were included. The periotest was used in 4 RCTs and 2 RCTs used RFA to measure MSI stability. All RCTs had a low RoB. Subgroup analyses based on periotest indicated that MSIs treated with LLLT had significantly higher stability than untreated MSIs at 21 and 30 days [weighted mean difference (MD) = -2.76, confidence interval (CI): [-4.17, -1.36], P-value = 0.0001) and at 60 days (weighted MD = -3.47, CI: [-4.58, -2.36], P < 0.00001); and the level of certainty was high. Subgroup analyses based on RFA showed higher stability of MSIs treated with than without LLLT at 56 and 60 days (standardized MD = 0.82, CI: [0.32, 1.32], P = 0.001), and at 70 and 90 days (standardized MD = 0.86, CI: [0.36, 1.36], P = 0.0007); and the level of certainty was moderate.

LIMITATIONS

Due to limited number of relevant studies, it was not possible to perform sensitivity analysis, subgroup analyses for patient and intervention-related characteristics, and reporting biases assessment.

CONCLUSIONS

The role of LLLT on the secondary stability of MSIs placed in patients undergoing OT remains debatable.

CLINICAL TRIAL REGISTRATION

PROSPERO (CRD42021230291).

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study

Introduction:

Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient.

Objective:

To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician.

Methods:

82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort.

Results:

The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only.

Conclusions:

Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

Cone-beam computed tomography assessment of bone using grayscale values in patients with diabetes mellitus. A case-control observational study

Background:

The density of cortical and cancellous bone is a key reason for implant anchorage which might be severely affected during diabetes.

Aim:

The aim of the study was to establish the role of cone-beam computed tomography (CBCT) using grayscale values in determining bone density in different jaw sites and in comparing the values in healthy with diabetic patients.

Materials and Methods:

Bone densities in 322 possible implant sites in healthy and diabetic patients were evaluated using NewTomGiano CBCT machine. Cross-sections obtained were assessed for bone densities in terms of Hounsfield Unit on different sites using New Net Technologies software version 6.1.

Statistical Analysis:

Data were statistically analyzed using SPSS software (version 19.0).

Results:

Age-wise cortical and cancellous bone densities were compared and no statistical significance was obtained. Gender-wise bone density was compared and significant results were found in males. Jaw-wise bone density was compared and was found to be significantly high in the mandible. The mean cortical bone density in control group was 1608.572 (±380.36), whereas in diabetic group was 1395.368 (±296.97), and the mean cancellous bone density in control was 906.918 (±185.40) and in diabetic was 559.868 (±128.16). Teeth wise in cortical bone significant values were found at premolar region (P = 0.046) and in cancellous bone significant values were found at canine and premolar region (P = 0.012) and highly significant values were found at molar region (P = 0.001).

Conclusion:

CBCT unveils a distinct pattern of cortical and cancellous bone density. A high degree of concordance between different regions of the mouth in cortical and cancellous bones was obtained in different study groups. CBCT could be used for bone density analysis.

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.

3D Analysis of Tooth Movement Using 3D Technology

PURPOSE OF REVIEW

3D cone beam imaging (CBCT) has allowed clinicians to better understand the anatomical variations of cranial anatomy. One crucial aspect of this technology plays is the understanding of alveolar bone morphology and remodeling. Variations in cortical bone thickness between individuals have been reported. No published study has analyzed the relationship between cortical bone thickness and rate of tooth movement. The aim of this study is to begin answering the question: is there an association between rate of tooth movement and cortical bone thickness?

RECENT FINDINGS

Twenty-three patients underwent extraction of a single premolar in each of the four quadrants prior to orthodontic therapy. Routine clinical records including 3D CBCT images were acquired of all patients prior to first premolar extractions. Rate of tooth movement in each quadrant for each patient was determined via mesiodistal millimetric measurements obtained by a single calibrated operator. With CBCT images, cortical bone thickness was measured at various levels from the alveolar crest along the long axis of the to-be-extracted first premolars. The association between cortical bone thickness and rate of tooth movement was analyzed. Statistically significant associations were found between rate of tooth movement and cortical bone thickness at levels 2 mm, 5 mm, and 8 mm, apical to the alveolar crest in both the right and left maxillary quadrants (p < 0.05). Statistically significant associations were found between rate of tooth movement and cortical bone thickness at levels 5 mm and 8 mm apical to the alveolar crest in both mandibular quadrants (p < 0.05). Increased cortical bone thickness was associated with decreased rate of tooth movement. There was no statistically significant association between rate of tooth movement and cortical bone thickness 2 mm apical to the alveolar crest of the to-be-extracted first premolars in the mandibular left nor right quadrants (p > 0.05). Results suggest an inverse relationship may exist between cortical bone thickness and rate of tooth movement in both the maxilla and mandible. Cortical bone thickness may have the potential to serve as a predictive tool for rate of orthodontic tooth movement.

Relationship between Cortical Bone Thickness and Cancellous Bone Density at Dental Implant Sites in the Jawbone

Dental implant surgery is a common treatment for missing teeth. Its survival rate is considerably affected by host bone quality and quantity, which is often assessed prior to surgery through dental cone-beam computed tomography (CBCT). Dental CBCT was used in this study to evaluate dental implant sites for (1) differences in and (2) correlations between cancellous bone density and cortical bone thickness among four regions of the jawbone. In total, 315 dental implant sites (39 in the anterior mandible, 42 in the anterior maxilla, 107 in the posterior mandible, and 127 in the posterior maxilla) were identified in dental CBCT images from 128 patients. All CBCT images were loaded into Mimics 15.0 to measure cancellous bone density (unit: grayscale value (GV) and cortical bone thickness (unit: mm)). Differences among the four regions of the jawbone were evaluated using one-way analysis of variance and Scheffe's posttest. Pearson coefficients for correlations between cancellous bone density and cortical bone thickness were also calculated for the four jawbone regions. The results revealed that the mean cancellous bone density was highest in the anterior mandible (722 ± 227 GV), followed by the anterior maxilla (542 ± 208 GV), posterior mandible (535 ± 206 GV), and posterior maxilla (388 ± 206 GV). Cortical bone thickness was highest in the posterior mandible (1.15 ± 0.42 mm), followed by the anterior mandible (1.01 ± 0.32 mm), anterior maxilla (0.89 ± 0.26 mm), and posterior maxilla (0.72 ± 0.19 mm). In the whole jawbone, a weak correlation (r = 0.133, p = 0.041) was detected between cancellous bone density and cortical bone thickness. Furthermore, except for the anterior maxilla (r = 0.306, p = 0.048), no correlation between the two bone parameters was observed (all p > 0.05). Cancellous bone density and cortical bone thickness varies by implant site in the four regions of the jawbone. The cortical and cancellous bone of a jawbone dental implant site should be evaluated individually before surgery.

Effect of enamel matrix derivative on alveolar ridge preservation in the posterior maxilla: A randomized controlled clinical trial

BACKGROUND

EMD has been considered to exert positive effects on wound healing, postoperative discomfort, and bone regeneration.

PURPOSE

The aim of this randomized controlled clinical trial was to investigate and compare (a) horizontal and vertical bone dimensional changes, (b) early postoperative discomfort and soft tissue wound healing outcomes, and (c) treatment modalities for implant placement, following posterior maxillary alveolar ridge preservation (ARP) with and without adjunctive use of EMD.

METHODS

Twenty-eight participants were randomly assigned to three groups: extraction sockets filled with bovine bone mineral and membrane with EMD (test group 1, n = 10) and without EMD (test group 2, n = 10) and spontaneous healing (control group, n = 8). Alveolar bone dimensional changes were measured using cone-beam computed tomography 5 months after ARP, and postoperative pain and wound healing outcomes were also evaluated.

RESULTS

There were no significant differences in horizontal or vertical bone dimensional changes between test groups 1 (horizontal width changes at 1 mm apically below the alveolar ridge crest [HW]: -1.44 ± 0.54 mm) and 2 (HW: -1.42 ± 0.26 mm), but the changes at HW (-2.36 ± 1.03 mm) in the control group were significantly greater than those in test groups 1 and 2 (P < .05). Early postoperative discomfort and soft tissue wound healing outcomes were not significantly different between the two test groups. Furthermore, unlike the control group, both the test groups 1 and 2 were implanted without sinus floor elevation using the lateral approach.

CONCLUSION

Within the limitations of this study, EMD failed to provide additional benefits in ARP in the posterior maxilla.

Optimal sites for mini-implant insertion in the lingual or palatal alveolar cortical bone as assessed by cone beam computed tomography in South Indian population

OBJECTIVES

To determine the optimal sites of mini-implant placement in the palatal alveolar cortical bone by using cone beam computed tomography (CBCT).

SUBJECTS AND METHODS

Cone beam computed tomography records of 60 patients were divided into two groups of equal sizes, based on age and sex. The images were analysed using Planmeca Romexis Software (Version 4.1.2). The measurements were made in axial sections of the maxilla and mandible, at 2, 4 and 6 mm from the CEJ. The optimal sites were defined in terms of (a) Palatal or lingual alveolar cortical bone thickness and (b) Mesiodistal palatal or lingual inter-radicular width.

RESULTS

The optimal site for mini-implant insertion, anteriorly, was the canine-lateral incisor embrasure in both the jaws. Posteriorly, the inter-molar embrasure in the mandible and the molar-premolar embrasure in the maxilla were optimal sites. Females demonstrated significantly lesser bone widths in all areas of the maxilla (P < .05) but greater bone thickness in the mandibular regions, as compared to males. The adolescent age group demonstrated a significantly lesser bone thickness but greater mesiodistal widths than the adult population in both the jaws (P < .05).

CONCLUSION

The optimal sites for mini-implant insertion were the anterior canine-lateral incisor and posterior buccal inter-radicular embrasures, in both the jaws. Significant differences existed between age and gender groups, which need to be kept in mind while choosing the locations for placing mini-implants.

Sex-, growth pattern-, and growth status-related variability in maxillary and mandibular buccal cortical thickness and density

Objective

The primary objective of this study was to quantitatively analyze the bone parameters (thickness and density) at four different interdental areas from the distal region of the canine to the mesial region of the second molar in the maxilla and the mandible. The secondary aim was to compare and contrast the bone parameters at these specific locations in terms of sex, growth status, and facial type.

Methods

This retrospective cone-beam computed tomography (CBCT) study reviewed 290 CBCT images of patients seeking orthodontic treatment. Cortical bone thickness in millimeters (mm) and density in pixel intensity value were measured for the regions (1) between the canine and first premolar, (2) between the first and second premolars, (3) between the second premolar and first molar, and (4) between the first and second molars. At each location, the bone thickness and density were measured at distances of 2, 6, and 10 mm from the alveolar crest.

Results

The sex comparison (male vs. female) in cortical bone thickness showed no significant difference (p > 0.001). The bone density in growing subjects was significantly (p < 0.001) lower than that in non-growing subjects for most locations. There was no significant difference (p > 0.001) in bone parameters in relation to facial pattern in the maxilla and mandible for most sites.

Conclusions

There was no significant sex-related difference in cortical bone thickness. The buccal cortical bone density was higher in females than in males. Bone parameters were similar for subjects with hyperdivergent, hypodivergent, and normodivergent facial patterns.

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.

Correlation between Dental Vestibular-Palatal Inclination and Alveolar Bone Remodeling after Orthodontic Treatment: A CBCT Analysis

The aim of this study was to evaluate the correlation between dental vestibular-palatal inclination changes and the cortical bone remodeling after fixed orthodontic treatment using cone beam computed tomography (CBCT). Twenty-two patients with Angle Class I malocclusion, permanent dentition, and mild to moderate dental crowding were included in the present three-dimensional (3D) analysis. Bone dimensions were evaluated by CBCT scans obtained before and after orthodontic treatment, whereas the torque values were calculated by means of digital models using the 3D VistaDent software. A paired t-test was used to compare the changes between the pretreatment and post-treatment measurements. The correlations between variables were analyzed with linear regression analysis. A significant correlation between torque variations and bone thickness changes was observed for the apical buccal level of the anterior side (P < 0.05). Limited and not significant alveolar bone resorption for the apical thickness of anterior teeth occurred at ± 5 degrees of torque variation, while for tooth inclination exceeding +5 or -5 degrees, the bone remodeling was more evident. The present study demonstrated that anterior region was the most affected area by bone remodeling and that torque variation was highly related to apical bone thickness adaptation for maxillary and mandibular incisors and maxillary canines.

Miniscrew-supported distal jet versus conventional distal jet appliance: A pilot study

Background

Maxillary molar distalization is the most frequently used nonextraction treatment in the correction of Class II malocclusion. The use of traditional intra-oral devices shows unreliable results. Nowadays the use of miniscrew-supported appliances helps prevent anchorage loss. The aim of this pilot study is to compare the amount of upper first molar distalization and the dentoalveolar side effects using traditional distal jet appliance and miniscrew-supported distal jet appliance.

Material and Methods

20 patients were randomly assigned to receive a treatment with miniscrew-supported distal jet appliance (Group A) or with traditional distal jet appliance (Group B). To ensure a safe and minimally invasive miniscrew insertion a surgical guide was used. Digital models and lateral cephalograms were obtained and analyzed before orthodontic treatment and at 6-month follow-up. Intergroup differences were determined using T- test. The significance was set at p ≤0.05. The intra-operator reliability was evaluated using a 2 sample T-test. The difference was not statistically significant (P ≤0.05 ), demonstrating an intra-operator reliability.

Results

In Group A, a greater maxillary first molar distalization was recorded (P=0.002). Considering the dentoalveolar side effects, in Group A, a spontaneous distalization of the first premolars and a retroclination of central incisors were determined. In Group B, the first premolars tipped mesially with a proclination of the maxillary central incisors.

Conclusions

Miniscrew-supported distal jet appliance achieved a greater first molar distalization at 6-month follow-up and did not cause dento-alveolar side effects, such as the mesial drift of the premolars and the incisors. Key words:Molar distalization, distal jet appliance, skeletal anchorage, miniscrew, 3D printed surgical guide.

Three-dimensional quantitative assessment of palatal bone height for insertion of orthodontic implants - a retrospective CBCT study

Background

Orthodontic implants have found widespread use as means of maximum skeletal anchorage in fixed orthodontic treatment, their optimal insertion location in the hard palate, however, is still controversial. The aim of this study was therefore to assess mean bone height across the hard palate and possible age- and sex related differences to identify the most favourable location according to maximum bone height, optimizing primary stability and survival of inserted orthodontic implants.

Methods

In this retrospective cross-sectional study, maxillary pretreatment CBCT scans of 180 healthy orthodontic patients (95♀, 85♂, age 8–40 years) were analysed with regard to vertical palatal bone height in the midpalatal area at 88 validated points distanced 2 mm from each other forming a grid of 0–14 mm posterior to the incisive foramen and 10 mm lateral of the midpalatal suture. Differences in bone height regarding sex and topographical location were assessed by three-way ANOVA.

Results

In general, the midpalatal suture as well as the anterior-lateral palatal region showed distinctly higher mean palatal bone height with its maximum 4 mm posterior of the incisive foramen, whereas bone height was limited at the posterior region of the midpalatal suture. Women generally had significantly decreased palatal bone height compared to men at all measurement points. Higher age was associated with a decrease of bone height in the anterior and posterior lateral palatal region and the median palatal raphe with significant age differences.

Conclusions

The midpalatal suture as well as the anterior lateral palate seem to be most suitable for the insertion of orthodontic implants. Palatal bone height, however, was found to be sex- and age-specific, thus sex- and age-related differences should be taken into account, particularly regarding implant length. The ideal insertion site in the palate with sufficient bone height for orthodontic implants is 0-8 mm (men) or 0-6 mm (women) posterior to the incisive foramen and 10 mm lateral to the midpalatal suture.

Trial registraion

This study has been registered and approved by the Ethics Committee of the University of Witten/Herdecke, Germany (12/2016).

Electronic supplementary material

The online version of this article (10.1186/s13005-019-0193-9) contains supplementary material, which is available to authorized users.

Influence of vertical misfit in screw fatigue behavior in dental implants: A three-dimensional finite element approach

Misfit is unavoidable in dental implant-supported prostheses due to machining process or inappropriate assembling, and the definition of an admissible misfit is still a controversial issue. This work aims to understand the behavior of the screws in dental implant-supported prostheses to estimate an admissible vertical misfit value in terms of screw fatigue failure. For that purpose, a finite element model of a dental implant-supported prosthesis was created and analyzed. Vertical misfits were introduced in different positions, the lower and upper screws were tightened to the bolting force values recommended by the manufacturer, and two different occlusal loads were analyzed. In addition, two different prosthesis materials were studied. Screw load variations were reported and a fatigue analysis was performed. As a result, it was observed that the screw tightening sequence closed small vertical misfits (equal to or less than 40 µm), whereas larger misfits (more than 40 µm) remained open. If the vertical misfit is closed by the end of the tightening sequence, it may be considered equivalent to the ideal fit situation in regard to screw fatigue failure. The prosthesis material had no significant influence on the fatigue behavior.

Performance of Cone Beam Computed Tomography Systems in Visualizing the Cortical Plate in 3D Image Reconstruction: An In Vitro Study

INTRODUCTION

Cortical bone is an important anatomical structure and its thickness needs to be determined prior to many dental procedures to ensure treatment success. Imaging modalities are necessarily used in dentistry for treatment planning and dental procedures. Three-dimensional image reconstruction not only provides visual information but also enables accurate measurement of anatomical structures; thus, it is necessarily required for maxillofacial examination and in case of skeletal problems in this region.

AIMS

This study aimed to assess the ability of three Cone Beam Computed Tomography (CBCT) systems including Cranex 3D, NewTom 3G and 3D Promax for Three-Dimensional (3D) image reconstruction of the cortical plate with variable thicknesses.

METHODS

Depending on the cortical bone thickness, samples were evaluated in three groups of ≤ 0. 5 mm, 0.6 -1 mm and 1.1-1.5 mm cortical bone thickness. The CBCT scans were obtained from each sample using three systems, their respective FOVs, and 3D scans were reconstructed using their software programs. Two observers viewed the images twice with a two-week interval. The ability of each system in the 3D reconstruction of different thicknesses of cortical bone was determined based on its visualization on the scans. The data were analyzed using SPSS and Kappa test.

RESULTS

The three systems showed the greatest difference in the 3D reconstruction of cortical bone with < 0.5 mm thickness. Cranex 3D with 4×6 cm2 FOV had the highest and 3D Promax with 8×8 cm2 FOV had the lowest efficacy for 3D reconstruction of cortical bone. Cranex 3D with 4×6 cm2 and 6×8 cm2 FOVs and NewTom 3G with 5×5 cm2 and 8×5 cm2 FOVs showed significantly higher efficacy for 3D reconstruction of cortical bone with 0.6-1mm thickness while 3D Promax followed by NewTom 3G with 8×8 cm2 FOV had the lowest efficacy for this purpose.

CONCLUSION

Most CBCT systems have high efficacy for 3D image reconstruction of cortical bone with thicknesses over 1 mm while they have poor efficacy for image reconstruction of cortical bone with less than 0.5 mm thickness. Thus, for accurate visualization of anatomical structures on CBCT scans, systems with smaller FOVs and consequently smaller voxel size are preferred.

Nutrient canals and porosity of the bony palate: A basis for the biological plausibility of the anterior middle superior alveolar nerve block

BACKGROUND

The authors investigated morphologic parameters of the palatal cortex that affect the diffusion of local anesthetic solution in the region of the anterior middle superior alveolar (AMSA) nerve block injection site.

METHODS

The authors used computed tomographic (CT) and micro-CT imaging to assess 20 human skulls from an anatomic collection. Analysis of the CT images included frequency, distribution, and width of the nutrient canals in the bony palate, according to to the person's sex and age. Micro-CT analysis involved measuring the thickness and porosity of palatal cortical bone in the area of the AMSA injection site in relation to the thickness and porosity of the opposite buccal cortical bone.

RESULTS

There was a statistically significant difference (P = .042) in the location of the nutrient canals between male specimens (> 50% in the border region) and female specimens (> 50% in the palatal process). Furthermore, the female skulls had significantly wider nutrient canal foramina (P = .042) than did the male skulls. Despite greater thickness, the palatal cortex in the area of the AMSA injection site had slightly greater porosity than did the buccal cortex. A significantly greater number of microcanals penetrated the whole cortical thickness in palatal than in buccal cortical bone (P = .001).

CONCLUSIONS

The distribution and width of nutrient canals differed between male and female skulls. At the microscopic level, structural characteristics of the palatal cortex provide a good anatomic basis for the potential of a satisfactory AMSA injection success rate.

PRACTICAL IMPLICATIONS

The AMSA technique success rate might be increased if the clinician adjusts the injection site to the distribution of nutrient canals, depending on the sex of the patient.

Palatal orthodontic miniscrew insertion using a CAD-CAM surgical guide: description of a technique

The aim of this report was to describe a new computer-guided technique for a controlled site preparation and palatal orthodontic miniscrew insertion using a dedicated software. A surgical guide was designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. Pre- and postoperative CBCT images were compared and the angular, coronal, and apical deviations between the planned and the placed miniscrews were calculated. The mean coronal and apical deviations were 1.38mm (range: 3.48-0.15mm; standard deviation (SD): 0.65) and 1.73mm (range: 5.41-0.10mm; SD: 1.03), respectively, while the mean angular deviation was 4.60° (range: 15.23-0.54°; SD: 2.54). The present surgical guide allows a controlled and accurate palatal miniscrew placement in three dimensions.

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.

COMPARATIVE STRESS ANALYSIS OF LINGUALIZED AND CONVENTIONAL BALANCED OCCLUSION SCHEMES IN A FULL-ARCH FIXED IMPLANT PROSTHESIS USING FINITE ELEMENT ANALYSIS

This study compares the biomechanical behavior of a mandibular full-arch fixed implant prosthesis with four implants under lingualized and conventional balanced occlusion schemes. The acrylic resin denture was supported by four titanium cylindrical implants and connected via a titanium prosthetic rectangular bar. Orthotropic material was used for the cortical and cancellous bones. The applied loadings were vertical and bilateral: 100[Formula: see text]N on first molar and 50[Formula: see text]N on first and second premolars each. For the lingualized balanced occlusion, the loadings were applied in central fossae of the posterior teeth, whereas for the conventional balanced occlusion the loadings were applied in central fossae and buccal cusps. The maximum von-Mises stresses for the lingualized and conventional balanced schemes were 301[Formula: see text]MPa and 25[Formula: see text]MPa, respectively, and were located at the neck of the posterior implants. In the denture teeth, the highest stress was located at the beginning of the cantilever extension. In the cortical bone, according to Tsai–Wu criterion, the failure index for the lingualized balanced occlusion was 1.10 and for the conventional balanced occlusion was 0.83. Thus, the conventional balanced occlusion demonstrated more favorable stress distribution in the implants and the cortical bone than the lingualized balanced occlusion.

Case Selection is Critical for Successful Outcomes Following Immediate Implant Placement in the Esthetic Zone

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Immediate versus delayed implant placement after anterior single tooth extraction: the timing randomized controlled clinical trial. Tonetti MS, Cortellini P, Graziani F, Cairo F, Lang NP, Abundo R, Conforti GP, Marquardt S, Rasperini G, Silvestri M, Wallkamm B, Wetzel A. Journal of Clinical Periodontology 2017;44(2):215-24.

SOURCE OF FUNDING

Nonprofit, Foundations: European Research Group on Periodontology, Genova, Italy Industry: Thommen Medical AG, Switzerland and Geistlich AG, Switzerland (biomaterials).

TYPE OF STUDY/DESIGN

Randomized controlled trial.

Three-D imaging of dental alveolar bone change after fixed orthodontic treatment in patients with periodontitis

OBJECTIVES

The objective of this study was to radiographically quantify bone height and bone density in patients with periodontitis after fixed orthodontic treatment using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 81 patients including 40 patients with chronic periodontitis (group 1) and 41 patients with normal periodontal tissues (group 2) were selected. CBCT scanning for anterior teeth were taken before and after orthodontic treatment. Measurements of bone height and bone density were performed using CBCT software.

RESULTS

The group 1 presented a statistically lesser bone density and bone height when compared to group 2 before treatment. There was a significant loss of bone density for both groups after orthodontic treatment, but bone density loss was significantly greater in the group 1. There was no statistically significant bone height change in two groups after treatment.

CONCLUSIONS

This study demonstrated that orthodontic treatment can preserve bone height but not capable of maintaining bone density, especially for patients with periodontitis. It is indicated that the change of bone density may be more susceptible than that of bone height when radiographically evaluating bone status under this combined periodontal and orthodontic therapy.

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.

Morphological and topographical characteristics of posterior supernumerary molar teeth: an epidemiological study on 25,186 subjects

Objectives: To investigate the prevalence , gender difference , arch , morphology and position within the arch of supernumerary molar (SM) teeth in a referred Italian Caucasian population. Study Design: Records of 25,186 young patients were evaluated. Only data related to supernumerary teeth in the posterior region of the jaws were analyzed. The diagnosis of hyperdontia was formulated during the clinical and radiological examinations based on panoramic radiographs. Statistical analysis was conducted at level of subjects in the assessment of prevalence of SMs and sex ratio. Statistical analysis was conducted at level of teeth according to their morphological and topographic characteristics. The analysis of association between supernumerary morphology and arch, between supernumerary position and arch and between morphology and position was performed using the χ2 test (P≤ 0.05). Results: 61 posterior supernumerary teeth were found in 45 patients. The male to female ratio was 2.5:1 ;the mean age was 21.23 (IC:95%).The SMs were found more frequently in the maxilla (62.3%) than in the mandible; supernumerary teeth (60.7%) were more frequent than supplemental teeth. The SMs were mostly of tuberculate shape (56.8%) and paramolars teeth (64.9%) were more common than distomolars. 54% of teeth were erupted in the arch. No statistically significant relationship were found between the supernumerary teeth shape and the arch (P= 0.087) , between supernumerary teeth position and the arch (P=0.511) and between morphology and position (P=0.216). Conclusions: Epidemiological studies related to supernumerary teeth can be useful to clinicians in the early diagnosis of this anomaly. In this retrospective study the prevalence of SMs was 0.18%. SMs were more frequent in males and in the maxilla. Supernumerary were more frequent than supplemental; the conical morphology and paramolar position were the most common shape and position.

Key words:Hyperdontia, prevalence, supernumerary molars, distomolar, paramolar.