Level Of Root Apex Research Articles

More molar distal movement than pretreatment cone-beam computed tomography posterior space available at the root level in mandibular dentition distalization with microimplants.

To compare the mandibular posterior space available before treatment and the distance of molar distalization achieved after mandibular dentition distalization with microimplants. A total of 66 Class I or III adult patients (mean age = 24.46 ± 4.89 years) who underwent molar distalization using microimplants were retrospectively included. The posterior space available distal to the second molar before treatment and the distance of distalization achieved after treatment were measured using axial cone-beam computed tomography images (0, 2, 4, and 6 mm apical to the second molar root furcation). Changes in lingual cortical thickness and molar root length after treatment were examined. Paired t-test or Wilcoxon signed-rank test was performed to compare measurements before and after treatment. Spearman correlation analysis was performed to assess the relationship between thinning of the cortical plate and root resorption. Achieved distalization distance was significantly greater than pretreatment posterior space available by 0.8 mm at all root levels (P < .001). The difference was greater toward the root apex level and greater in the Class III group than the Class I group. Lingual cortical thickness was significantly decreased after treatment along with resorption of the second molar distal root (P < .001). In addition, a positive correlation was found between thinning of the cortical plate and distal root resorption of the molar (P < .001). Achieved distalization distance of the mandibular molar using microimplants was greater than the pretreatment posterior space available. Thinning of the lingual cortex and root resorption were observed after distalization.

Alveolar bone changes around maxillary incisors after intrusion and retraction with controlled tipping versus bodily movement : Aretrospective cone-beam computed tomography study.

To compare the effect of maxillary incisor intrusion and retraction with controlled tipping (CT) versus bodily movement (BM) in extraction cases on alveolar bone height and thickness, using cone-beam computed tomography (CBCT). Correlations between changes in alveolar dimensions and crown or root retraction, incisor inclination, and intrusion were also investigated. In all, 144 incisors of 36 women were retrospectively evaluated. All patients were treated with anterior intrusion and retraction with either controlled tipping (CT) (group1) or bodily movement (BM) (group2). CBCT scans were taken before and after retraction and intrusion and measurements of alveolar bone height and thickness at the level of mid-root and root apex were measured. The prevalence of dehiscence was also calculated. Labial bone thickness (BT) increased at the level of the root apex with increased total BT in the CT group (p < 0.05). The BM group showed decreased palatal BT. Significant vertical bone loss with an increased incidence of dehiscences occurred on the palatal side in both groups. Changes in palatal bone area was negatively correlated with the amount of root apex retraction, while the total BT at the level of root apex was positively correlated with amount of intrusion. Bodily retraction can result in reduced palatal bone dimensions and an increase risk of iatrogenic sequelae following anterior retraction in extraction cases. Vertical bone loss and an increased incidence of dehiscences is to be expected following anterior retraction. Careful attention must be paid to the bone boundary conditions to avoid moving the incisors out of the alveolar housing.

Assessment and Correlation of Variation in Lingual Cortical Plate Thickness with Different Angulations of Impacted Mandibular Third Molar Using Cone Beam Computed Tomography in North Indian Population.

The extraction of impacted mandibular third molar is associated with various types of intraoperative and postoperative complications, one of them is injury to lingual nerve. The present study aims to assess and correlate the variation in lingual cortical plate thickness with different angulations and determine the topographic relationship between the root apex of impacted mandibular third molar and lingual cortical plate using Cone Beam Computed Tomography (CBCT). This prospective cohort study enrolled 140 patients with impacted mandibular third molars who underwent preoperative CBCT imaging. The CBCT images were used to evaluate the outcome variables such as lingual cortical plate thickness and topographical relationship between root apex of impacted mandibular third molar and lingual cortical plate. The predictor variables included age, gender, inclination of third molar, mesiodistal angle, buccolingual angle and lingual plate morphology. The temporary lingual nerve paresthesia was reported by 1 patient (0.71%) out of 140 patients. The lingual bone in distoangular and vertical impacted third molar was found to be 1.20 times thicker than mesioangular and horizontal teeth. Lingual bone thinning at mid-root level was observed in maximum number of cases with mesioangular teeth (68.5%), whereas horizontal impacted teeth showed lingual bone thinning (90.9%) at root apex level. The mean buccolingual angle of impacted mandibular third molar was found to be significantly associated with lingual bone perforation (p value = 0.0258). The morphology of lingual plate was observed as undercut type (37.14%) followed by slanted (36.43%), parallel (19.29%) and round type (7.14%). Increase in buccolingual angle of impacted mandibular third molar decreases lingual bone thickness which is the natural barrier for protecting injury to lingual nerve. Also undercut and slanted lingual plate shapes were recognised as risk factors for contact/perforation between root apex and lingual plate. Therefore, proper screening and planning of high risk patients before third molar extraction is crucial.

Biomechanical effect of selective osteotomy and corticotomy on orthodontic molar uprighting

Uprighting mesially tipped molars is often a necessary step before implant placement. However, the orthodontic treatment can be lengthy and discourage patients from choosing implant prostheses. Periodontally accelerated osteogenic orthodontics is reported to facilitate molar movements. This study aimed to evaluate the biomechanical effects of various corticotomy and osteotomy approaches on the uprighting of a mesially tipped mandibular secondmolar in a 3-dimensional finite element analysis model. The initial tooth displacement and periodontal ligament (PDL) strain in 9 finite element analysis models with various corticotomy and osteotomy simulations were compared under 3 intended tooth movement scenarios: distal crown tipping, mesial root movement with restraints, and mesial root movement without restraints. Corticotomy or osteotomy approaches altered the tooth displacement and the PDL strain in all 3 intended molar uprighting scenarios. The 2 most extensive surgical approaches, the combined mesial and distal osteotomy with horizontal corticotomy and the circumferential corticotomy at root apex level, resulted in increased tooth movement but had a distinct impact on PDL strain. It was revealed that different combinations of corticotomy and osteotomy had a biomechanical impact on orthodontic molar uprighting movements.

An isopentenyl transferase transgenic wheat isoline exhibits less seminal root growth impairment and a differential metabolite profile under Cd stress.

Cadmium is one of the most important contaminants and it induces severe plant growth restriction. In this study, we analyzed the metabolic changes associated with root growth restriction caused by cadmium in the early seminal root apex of wheat. Our study included two genotypes: the commercial variety ProINTA Federal (WT) and the PSARK ::IPT (IPT) line which exhibit high-grade yield performance under water deficit. Root tips of seedlings grown for 72 h without or with 10μM CdCl2 (Cd-WT and Cd-IPT) were compared. Root length reduction was more severe in Cd-WT than Cd-IPT. Cd decreased superoxide dismutase activity in both lines and increased catalase activity only in the WT. In Cd-IPT, ascorbate and guaiacol peroxidase activities raised compared to Cd-WT. The hormonal homeostasis was altered by the metal, with significant decreases in abscisic acid, jasmonic acid, 12-oxophytodienoic acid, gibberellins GA20, and GA7 levels. Increases in flavonoids and phenylamides were also found. Root growth impairment was not associated with a decrease in expansin (EXP) transcripts. On the contrary, TaEXPB8 expression increased in the WT treated by Cd. Our findings suggest that the line expressing the PSARK ::IPT construction increased the homeostatic range to cope with Cd stress, which is visible by a lesser reduction of the root elongation compared to WT plants. The decline of root growth produced by Cd was associated with hormonal imbalance at the root apex level. We hypothesize that activation of phenolic secondary metabolism could enhance antioxidant defenses and contribute to cell wall reinforcement to deal with Cd toxicity.

Architectural changes in alveolar bone for dental decompensation before surgery in Class III patients with differing facial divergence: a CBCT study

This study aimed to investigate alveolar bone change around mandibular anterior teeth during orthodontic decompensation in patients with skeletal Class III malocclusion and different vertical facial patterns. The records of 29 consecutive Class III patients selected from those pending two-jaw orthognathic surgery were divided into low (≤ 28°), average (30°–37°), and high (≥ 39°) mandibular plane angle (MPA) groups. The DICOM files of CBCT scans and STL files of digital dental models, taken before (T1) and after (T2) presurgical orthodontic treatment, were imported into Dolphin imaging software to reconstruct dentoskeletal images. T1 and T2 images were superimposed and analyzed for bone thickness and height at the level of root apex on each mid-sagittal slice of six mandibular anterior teeth. Differences between T1 and T2 were analyzed by non-parametric tests and mixed-effect model analysis. The results showed that the measurements of alveolar bone height generally decreased after treatment, regardless of MPA. The facial divergence, incisor irregularity, tooth site, treatment time, and change in proclination were identified as the significant factors affecting alveolar bone thickness and height during treatment. The presurgical orthodontic treatment to decompensate mandibular anterior teeth should be very careful in all MPA groups.

Incidence of Pre-Existing Lingual Cortex Perforation Before Removal of Mandibular Third Molars

The objective of this study was to determine the relationship between the mandibular third molar tooth (Md3) and the adjacent lingual cortical bone and determine the incidence of lingual cortex perforation by Md3s. This retrospective study was designed and implemented from 100 cone-beam computed tomographic scans (CBCTs) of patients with age ranging from 18 to 65years old. The primary outcome was to assess the incidence of mandibular third molars (Md3s) with existing lingual cortex perforation by their roots. Perforation was assessed at the level of root apex and the most lingual portion on the apical half of the root. Other outcome variables included average thickness of covering lingual bone in the nonperforation group, lingual cortex morphology, impaction, and demographics. Descriptive statistics were computed. More than half the radiographs showed lingual cortex perforation at the level of root apex and most lingual portion on the apical one half of the root (51.2% and 52.8%, respectively). The average thickness of the covering lingual bone was 1.25mm around the root apex and 0.93mm around the most lingual portion on the apical half of the root. The most common lingual cortex morphology was the undercut shape. There was statistically significant association between the presence of Md3 impaction and perforation at both root levels [(P value<.001, Effect size=0.378) and (P value<.001, Effect size=0.445)]. Perforation of the lingual cortex by Md3s, whether erupted or impacted, was found in >50% of patients as determined by a preoperative CBCT scan. Therefore, the finding of lingual cortex perforation after removal of Md3s is likely to be evidence of a pre-existing condition rather than a result of surgery.

Morphometric evaluation of the alveolar bone around central incisors during surgical orthodontic treatment of high-angle skeletal class III malocclusion.

To evaluate morphometric characteristics of alveolar bone around the incisors of high-angle skeletal class III patients receiving surgical orthodontic treatment. Thirty high-angle skeletal class III patients (mean age, 20.94±3.25years) underwent cone-beam computed tomography before treatment (T0), after pre-surgical orthodontic treatment (T1) and after treatment (T2). The vertical bone level (VBL), alveolar bone thickness (ABT), alveolar bone area (ABA) and position of upper and lower central incisors (UCIs and LCIs) were evaluated. The ABT included five levels (4, 6, 8mm from the cemento-enamel junction, midroot and root apex level). One-way repeated measures ANOVA with Bonferroni's multiple-comparison test and matched t test was performed to compare variables. Before treatment, the average labial ABT was approximately 1mm in UCIs and 0.38~0.79mm in LCIs, and the VBL of the LCIs was over 2mm. After treatment, the VBL increased by 2.19±1.96mm (P<.001) on the lingual side of UCIs and 2.78±2.29mm and 3.09±2.52mm on the labial and lingual sides of LCIs, respectively (all P<.001). ABT at every level decreased significantly, decreasing by 1.66±1.93mm at the 8mm level of UCIs and 1.06±1.01mm at the apex of LCIs (P<.001). The lingual ABA of UCIs and LCIs decreased by over 50% (P<.001). In high-angle skeletal class III patients, the condition of alveolar bone around UCIs and LCIs was extremely poor before treatment. Further alveolar bone resorption occurred during surgical orthodontic treatment. More attention should be paid to the movement of anterior teeth in cases of severe alveolar bone loss.

Cone beam computed tomographic-Based retrospective study on newark population for the assessment of distance between incisive canal and maxillary central incisors: Clinical implications.

To calculate the relative distance between the incisive canal and maxillary central incisors using cone beam computed tomography (CBCT) and utilize the results in treatment planning in a clinical setting. A retrospective study was conducted on CBCT taken for other purposes in the Oral and Maxillofacial Radiology Department. All the quantitative measurements were performed between the incisive canal and both maxillary central incisors using CBCT on 61 subjects. The anterior-posterior measurements were taken on both sides and the average of both values was considered for the statistical analysis. All the linear measurements were performed on the axial plane at three different vertical reference points located on the sagittal plane. The interexaminer reliability was tested by interclass correlation coefficient using two-way mixed and absolute agreement model. The comparison of linear measurement among each level was done by "Repeated measure ANOVA" and contrast method was used for pair-wise comparison when repeated measure analysis of variance (ANOVA) was significant. The average anterior-posterior distance between the maxillary central incisor roots and the incisive canal measured was approximately 5-6 mm. The incisive canal width increases from the root apex level of maxillary central incisors (P3) to the oral opening level of the incisive canal (P1). The results of our study could be helpful in a clinical setting requires significant retraction of maxillary incisors or implant placement in maxillary anterior region.

Long-term Effects of Augmented Corticotomy-Assisted Orthodontics in Patients With Mandibular Anterior Alveolar Defect.

The purpose of this study was to quantitatively investigate the long-term effects of augmented corticotomy-assisted orthodontics in adult patients with alveolar defect in mandibular anterior region. Thirty lower incisors with alveolar defect on the labial sides were included in this study from 10 adult patients received augmented corticotomy-assisted orthodontics in mandibular anterior region. Cone-beam computed tomography images were obtained before orthodontic treatment (T0), 3 months after augmented corticotomy (T1) and 2 years after removal of orthodontic appliance (T2). Measurements of variables at different time points were compared using Student-Newman-Keuls test. Each patient completed augmented corticotomy-assisted orthodontics successfully. In the 30 subjects studied, root length and bone thickness on the labial side at 1/2 root length level were maintained from T0 to T2 (P >.05). Bone thickness at 3/4 root length level increased from T0 to T1 (P <.001), then decreased from T1 to T2 (P <.001), and which of T2 is greater than that of T0 (P <.001). Bone thickness at root apex level increased from T0 to T1 (P <.001), and remained steady from T1 to T2 (P >.05). Augmented corticotomy-assisted orthodontics is a promising approach for the treatment of adult patients with alveolar defect, which showed stable long-term effect of bone augmentation and minimal periodontal iatrogenic sequelae during treatment.

CONE BEAM COMPUTED TOMOGRAPHIC ASSESSMENT OF THE DISTANCE BETWEEN THE INCISIVE CANAL AND MAXILLARY CENTRAL INCISORS

Background Maxillary anterior teeth play an important role in aesthetics, phonetics, and mastication. Because of the aesthetic and functional significance, it is important to evaluate their position in association with surrounding structures in 3-D before initiating orthodontic treatment. With the advent of cone beam computed tomography (CBCT) in orthodontic diagnosis, it is now possible to identify these structures. One such structure is the incisive canal. Uncertainty in locating the canal can cause root resorption postorthodontic retraction of anterior maxillary teeth. Objective(s) The aim of this study was to calculate the relative distance between the incisive canal and maxillary central incisor using CBCT and utilize the results for orthodontic treatment planning. Study Design All quantitative measurements between the incisive canal and both maxillary central incisors were performed using CBCT on 61 patients. The anteroposterior measurements were taken on both sides, and the average of both values was considered for the statistical analysis. The Steiner cephalometric analysis was performed to select patients with skeletal and dental Class I relationship. All linear measurements were performed on the axial plane at 3 different vertical reference points located on the sagittal plane: (1) the palatal opening of the incisive canal (opening level, P1), (2) midlevel between the opening level and the root apex of the maxillary central incisors (midlevel, P2), and (3) the root apex of the maxillary central incisors (root apex level, P3). Results The average anteroposterior distance between the maxillary central incisor roots and the incisive canal was approximately 56 mm. Discussion/Conclusions The results of our study could be clinically helpful to plan orthodontic treatment that requires significant retraction of maxillary incisors. The authors support the idea of a pretreatment CBCT in cases that require maximum anterior retraction in the maxilla. Maxillary anterior teeth play an important role in aesthetics, phonetics, and mastication. Because of the aesthetic and functional significance, it is important to evaluate their position in association with surrounding structures in 3-D before initiating orthodontic treatment. With the advent of cone beam computed tomography (CBCT) in orthodontic diagnosis, it is now possible to identify these structures. One such structure is the incisive canal. Uncertainty in locating the canal can cause root resorption postorthodontic retraction of anterior maxillary teeth. The aim of this study was to calculate the relative distance between the incisive canal and maxillary central incisor using CBCT and utilize the results for orthodontic treatment planning. All quantitative measurements between the incisive canal and both maxillary central incisors were performed using CBCT on 61 patients. The anteroposterior measurements were taken on both sides, and the average of both values was considered for the statistical analysis. The Steiner cephalometric analysis was performed to select patients with skeletal and dental Class I relationship. All linear measurements were performed on the axial plane at 3 different vertical reference points located on the sagittal plane: (1) the palatal opening of the incisive canal (opening level, P1), (2) midlevel between the opening level and the root apex of the maxillary central incisors (midlevel, P2), and (3) the root apex of the maxillary central incisors (root apex level, P3). The average anteroposterior distance between the maxillary central incisor roots and the incisive canal was approximately 56 mm. The results of our study could be clinically helpful to plan orthodontic treatment that requires significant retraction of maxillary incisors. The authors support the idea of a pretreatment CBCT in cases that require maximum anterior retraction in the maxilla.

The preliminary study for three-dimensional alveolar bone morphologic characteristics for alveolar bone restoration

BackgroundThe concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone.MethodsThis study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed.ResultsThe horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level.ConclusionsThe results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

3D CBCT morphometric assessment of mental foramen in Arabic population and global comparison: imperative for invasive and non-invasive procedures in mandible

Background: Recent advancements in clinical dentistry have increased the possibilities of surgical procedures in the mental region. A detailed knowledge of mental foramen (MF) morphometry is significant to preserve integrity of the mental nerve trunk in surgical interventions such as orthognathic surgery, implant placement and anaesthetic block.Objective: The aim of this study was to determine the most accurate position of the mental foramen by using new assessment approach in a sample of dental patients presenting to the specialist dental clinic, College of Dentistry, Al Jouf University, Saudi Arabia.Study design: A retrospective study was performed using cone beam computed tomography (CBCT) of 600 patients (40.1 ± 11.78 years old). Following inclusion and exclusion criteria, 395 CBCT were finally obtained and analyzed for the most accurate position of the mental foramen (MF) by OnDemand 3D software (Seoul, Korea). Prevalence of shape of MF and accessory MF were also assessed. Pearson chi-square test was employed to test significant differences between genders and races.Results: The most common horizontal and vertical position of the mental foramen was in line with the long axis of 2nd premolar (41.3%) and below the root apex level (93.2%), respectively. The most common shape of MF was round type (72.66%). The prevalence of accessory 2MF and 3MF was 2.28% and 0.25%, respectively.Conclusion: New information about MF presented in this article can help anatomists, prosthodontists, orthodontists, surgeons, forensic odontologists and paleoanthropologists to predict the position of the MF and perform safer surgeries.

Topographic relationship between root apex of mesially and horizontally impacted mandibular third molar and lingual plate: cross-sectional analysis using CBCT.

The present study was aimed to determine the topographic relationship between root apex of the mesially and horizontally impacted mandibular third molar and lingual plate of mandible. The original cone beam computed tomography (CBCT) data of 364 teeth from 223 patients were retrospectively collected and analyzed. The topographic relationship between root apex and lingual plate on cross-sectional CBCT images was classified as non-contact (99), contact (145) and perforation (120). The cross-sectional morphology of lingual plate at the level of root apex was defined as parallel (28), undercut (38), slanted (29) and round (4). The distribution of topographic relationship between root apex and lingual plate significantly associated with gender, impaction depth, root number and lingual plate morphology. Moreover, the average bone thickness of lingual cortex and distance between root apex and the outer surface of lingual plate were 1.02 and 1.39 mm, respectively. Furthermore, multivariate regression analyses identified impaction depth and lingual plate morphology as the risk factors for the contact and perforation subtypes between root apex and lingual plate. Collectively, our findings reveal the topographic proximity of root apex of impacted mandibular third molar to the lingual plate, which might be associated with intraoperative and postoperative complications during tooth extraction.

Alveolar bone thickness and root length changes in the treatment of skeletal Class III patients facilitated by improved corticotomy: a cone-beam CT analysis

To evaluate the alveolar bone thickness and root length changes of anterior teeth with cone-beam computed tomography (CBCT). CBCT scans were taken for 12 skeletal Class III patients who accepted the improved corticotomy (IC) procedures during pre-surgical orthodontics. The CBCT data in T1 (the maxillary dental arch was aligned and leveled) and T2 (extraction space closure) were superimposed and the alveolar bone thickness at root apex level and root length measurements were done. From T1 to T2, the buccal alveolar bone thickness for the upper lateral incisors increased from (1.89±0.83) to (2.47±1.02) mm (P<0.05), and for central incisors and for canines from (2.32±0.71) to (2.68±1.48) mm and from (2.28±1.08) to (2.41±1.40) mm, respectively. According to Sharpe Grading System, the root resorption grade for 69 teeth of 72 was located in Grade 1, two teeth in Grade 2, one tooth in Grade 3. The improved corticotomy had the potential to increase the buccal alveolar bone thickness and the root resorption in most teeth was in Grade 1 according to Sharpe grading system.

Correlation between cortical plate proximity and apical root resorption

Root resorption is one of the most common iatrogenic sequelae of orthodontic treatment. Recently, root contact with the labial or palatal cortical plate at root apex level during orthodontic tooth movement was reported to be related to root resorption, and dentofacial morphology was suggested to predispose certain persons to root contact with the cortical plate. In this study, we constructed a best-fit straight line for the maxillary palatal cortical plate and set a line for the labial cortical plate from A point to Prosthion point in order to obtain measurements of proximity of root apices with the cortical plates of the maxillary alveolus. We investigated the correlation between apical root resorption and the measured variables. Our findings suggest that root approximation to the palatal cortical plate during orthodontic treatment could explain approximately 12% of the variance observed in the level of root resorption and the maxillary alveolar bone width about 2%. Tooth extrusion and crown lingualization also contributed to root resorption. We concluded that maxillary central incisor apical root resorption is influenced by root approximation to the palatal cortical plate during orthodontic treatment. (Am J Orthod Dentofacial Orthop 1998;114:311-8.)