Movement Of Molars Research Articles

How malocclusion interferes with tissue inhibitor of metalloproteinase-1 expression and morphology of the articular cartilage of the mandible in female rats

ObjectiveThe purpose of this study was to investigate morphological alterations and tissue inhibitor of metalloproteinase-1 expression in the articular cartilage of the mandible under conditions of experimentally induced malocclusion. DesignTwenty-four 8-week-old female Wistar rats were used and divided into control and experimental groups with two different treatment periods (2 and 4 weeks). Sagittal malocclusions were orthodontically created, causing mesial movement of the first molars and distalization of the third molars unilaterally and on opposite sides of the arches. Sagittal sections of the articular cartilage of the mandible were subjected to hematoxylin and eosin and immunohistochemistry for tissue inhibitor of metalloproteinase-1. Chi-square and MannWhitney U tests were applied. ResultsAnimals treated for 2 and 4 weeks showed morphological alterations in articular cartilage of the mandible. The main findings were thickening of the posterior third, layer derangement, osteoclast activity and osteophyte formation. Among the cellular aspects, the presence of chondrocytes with condensed nuclei and cytoplasm reduction were observed. The enzyme in control animals was observed only in the mature layer. Treated animals showed immunopositive cells in the proliferative and mature layers, and in the 2-week treated group, the posterior third of the cartilage had more immunolabeled cells than control (P=0.0291). ConclusionsThe occlusal disorder caused morphological changes in articular cartilage of the mandible, probably due to the attempt to adapt to the new condition. Tissue inhibitor of metalloproteinase-1 expression may play a role as an initial modulator in the biological events observed in articular cartilage of the mandible.

The effects of fulvic acids and low-level laser therapy on orthodontic retention in rats

BackgroundShortening retention time and minimizing relapse rates are ongoing challenges in orthodontics. This study investigated the effects of natural fulvic acids (FAs) and low-level laser therapy (LLLT) on orthodontic retention in rats.MethodsSeventy-two male Sprague-Dawley rats underwent mesial movement of the left maxillary first molar using a 50 g force via a nickel-titanium tension spring. After three weeks of movement, the rats entered the retention phase with retainer wires and were divided into four groups: Control (no intervention), FAs (80 mg/kg orally daily), LLLT (808 nm laser twice weekly), and FAs + LLLT (both treatments). Retainers were removed on days 7, 14, and 21 for a 3-day relapse assessment. Maxillary impressions were analyzed for relapse rates using 3Shape software, alongside histological and immunohistochemical evaluations of bone morphogenetic protein-2 (BMP-2) expression in periodontal tissues, with differences among groups analyzed using an ordinary two-way analysis of variance (ANOVA).ResultsThe relapse rate decreased over time, particularly at 10, 17, and 24 days (p < 0.001). The FAs group did not significantly affect relapse rates compared to the control group (p = 0.084). In contrast, both the LLLT and FAs + LLLT groups significantly reduced relapse rate (p < 0.001), with no significant difference between these groups (p = 0.555). Histological examination revealed active osteoclasts on day 10, decreasing by days 17 and 24. The LLLT and FAs + LLLT groups showed less local cementum resorption and better periodontal fiber arrangement. All treatment groups significantly increased BMP-2 expression (P < 0.05) compared to controls. with LLLT and FAs + LLLT differing significantly from FAs (P < 0.001), though no difference was observed between LLLT and FAs + LLLT (P = 0.578).ConclusionsFAs did not significantly reduce relapse rate with retainers, while LLLT effectively reduced relapse rates, showing no additional benefit from combining FAs with LLLT. Both FAs and LLLT increased BMP-2 expression in PDL fibroblasts but with no synergistic effect.

Comparison of the Effects of Different Palatal Morphology on Maxillary Expansion via RME and MSE: A Finite Element Analysis.

This study aims to compare and analyze the biomechanical effect and the displacement trend of RME and MSE on the maxillofacial complex under different palatal shapes by using finite element analysis. The three-dimensional model of maxillofacial complex was obtained from a computed tomography image of a person with a normal palate. Then, we modified the shape of the palate to obtain the model with a high palate. Additionally, two expander devices were considered. MSE and RME were created and four models were made: Model 1: Normal-palate craniomaxillofacial complex with RME expander; Model 2: Normal-palate craniomaxillofacial complex with MSE expander; Model 3: High-palate craniomaxillofacial complex with RME expander; Model 4: High-palate craniomaxillofacial complex with MSE expander. Then, lateral forced displacement was applied and the analysis results were obtained. The lateral displacement of the palatal suture of Model 3 is greater than that of Model 1, and the maxilla has more rotation. The crown/root ratio of Model 1 is significantly greater than that of the other three groups. Compared with Model 1, Model 3 has greater stress concentration in the superstructure of the craniomaxillofacial complex. Both of them have greater stress in the anchorage area than Model 2 and Model 4. Different shapes of the palate interfere with the effects of RME and MSE, and its influence on the stress distribution and displacement of the craniomaxillary complex when using RME is greater than MSE. The lateral displacement of the palatal suture of MSE is significantly larger than that of RME. It is more prone to tipping movement of the anchor teeth using RME under normal palate, and MSE may manage the vertical control better due to the smaller crown/root ratio than RME and intrusive movement of molars.

Taming the vertical growth of mandible in a growing patient with skeletal open bite: A case report

Skeletal open bite poses a significant challenge due to its association with downward and backward mandibular rotation and vertical maxillary overgrowth. Early intervention is critical, especially in patients with a hyperdivergent skeletal phenotype, as facial growth patterns are established early in development. This case report details the treatment of a 9-year-old male with a severe anterior open bite of 6 mm, vertical growth pattern, and class I skeletal relationship. Initial treatment included high-pull headgear with an intraoral transpalatal arch and tongue cribs to control the molar eruption and tongue posture. Over nine months, this approach reduced the open bite by restricting maxillary molar movement and promoting mandibular autorotation. In the second phase of treatment, temporary anchorage devices (TADs) were placed in the parasagittal region along with a transpalatal arch to achieve active molar intrusion and improve incisor exposure. The combination of orthopedic appliances and TADs successfully eliminated the open bite and corrected overjet, while improving incisor alignment, facial profile, and smile esthetics. Cephalometric analysis revealed a reduction in the mandibular plane angle, lower anterior facial height, and improved incisor extrusion. This case highlights the efficacy of early skeletal open bite correction using non-surgical methods, with TADs providing effective molar intrusion and stable long-term results. The integration of headgear and skeletal anchorage offers an effective treatment modality for young patients with severe open bites, potentially eliminating the need for more invasive surgical procedures in the future.

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.

Effectiveness of Clear Aligners on Sequential Maxillary Molar Distalization: Discrepancy between Treatment Goal and Outcome.

Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement.

The treatment effects of maxillary asymmetric mechanics with the use of the mesial-distalslider: A retrospective study

This study had 2 objectives: (1) to evaluate the clinical efficacy of the Mesial-Distalslider (MD) appliance when used for simultaneous maxillary molar mesialization and distalization in patients with a maxillary asymmetrical relationship and (2) to compare the outcomes with those achieved using the unilateral Mesialslider (UM) appliance. The sample included 40 subjects (25 females and 15 males) with a mean age of 22 years (range, 8-55 years). The patients were divided into 2 groups: 20 patients treated with an MD appliance (group 1) and a group of 20 patients treated with a UM appliance (group 2). Superimposition of digital dental models using regions of interest on the palate was performed to evaluate the 3-dimensional molar movements, the proclination or retroclination of the maxillary incisors, and the displacement of the maxillary midline. At the end of the treatment, the MD group's total movements were 4.5 ± 2.2 mm (sagittal), -0.4 ± 2.4 mm (transverse), and 0.3 ± 0.9 mm (vertical) along the mesialization side and -2.4 ± 1.7 mm (sagittal), -0.5 ± 1.5 mm (transverse), and 0.2 ± 1.4 (vertical) along the distalization side. UM group total movements were 5.5 ± 3.6 mm (sagittal), -0.4 ± 2.7 mm (transverse), and 0.1 ± 2.0 mm (vertical). Incisor displacements were minimal. No statistically significant differences were found between the MD and UM groups for all the parameters. The use of the MD enables controlled movements in the sagittal direction with negligible dental side effects in the other planes (transverse and vertical). Furthermore, it facilitates asymmetrical movements simultaneously in the desired direction without the patient's compliance and provides good anchorage control.

MiR-20a: a key regulator of orthodontic tooth movement via BMP2 signaling pathway modulation

ABSTRACT Aim In this study, we aimed to establish a rat tooth movement model to assess miR-20’s ability in enhancing the BMP2 signaling pathway and facilitate alveolar bone remodeling. Method 60 male SD rats had nickel titanium spring devices placed between their left upper first molars and incisors, with the right side serving as the control. Forces were applied at varying durations (18h, 24h, 30h, 36h, 42h, 1d, 3d, 5d, 7d, 14d), and their bilateral maxillary molars and surrounding alveolar bones were retrieved for analysis. Fluorescent quantitative PCR was conducted to assess miR-20a, BMP2, Runx2, Bambi and Smad6 gene expression in alveolar bone, and western blot was performed to determine the protein levels of BMP2, Runx2, Bambi, and Smad6 after mechanical loading. Result We successfully established an orthodontic tooth movement model in SD rats and revealed upregulated miR-20a expression and significantly increased BMP2 and Runx2 gene expression and protein synthesis in alveolar bone during molar tooth movement. Although Bambi and Smad6 gene expression did not significantly increase, their protein synthesis was found to decrease significantly. Conclusion MiR-20a was found to be involved in rat tooth movement model alveolar bone remodeling, wherein it promoted remodeling by reducing Bambi and Smad6 protein synthesis through the BMP2 signaling pathway.

Effects of different tooth movement patterns and aligner thicknesses on maxillary arch expansion with clear aligners: a three-dimensional finite element study.

The objective of this study was to investigate the biomechanical effects of different tooth movement patterns and aligner thicknesses on teeth and periodontal tissues during maxillary arch expansion with clear aligners, to facilitate more precise and efficient clinical orthodontic treatments. Three-dimensional models including teeth, maxilla, periodontal ligament, and aligner were constructed and subjected to finite element analysis. Tooth displacement trends and periodontal ligament stresses were measured for seven tooth displacement patterns (divided into three categories including overall movement of premolars and molars with gradually increasing molar expansion in each step; distributed movement of premolars and molars; and alternating movement between premolars and molars at intervals) and two aligner thicknesses (0.5mm and 0.75mm) during maxillary arch expansion with clear aligners. When expanding the maxillary arch with clear aligners, the effective expansion of the target teeth mainly showed a tilting movement trend. Increasing the amount of molar expansion increased the buccal displacement of the first molar but decreased the buccal displacement of the premolars. The mean buccal displacement of the target teeth was greater in the posterior teeth interval alternating movement group (0.026mm) than in the premolar/molar distributed movement group (0.016mm) and the overall movement group (0.015mm). Increasing aligner thickness resulted in greater buccal displacement of the crowns and increased stress on the periodontal ligaments. Increasing the amount of molar expansion reduces the efficiency of premolar expansion. Alternating movement of premolars and molars at intervals achieves a higher arch expansion efficiency, but attention should be paid to the anchorage of adjacent teeth. Increasing the thickness of the aligner increases the expansion efficiency but may also increase the burden on the periodontal tissues.

Orthodontic maxillary molar movement-induced zygomatic pillar remodeling and its consequences on occlusal characteristics and stress distribution

ObjectiveWe aimed to evaluate changes in the zygomatic pillar during orthodontic treatment involving premolar extraction, analyze the effects of maxillary first molar movement on zygomatic pillar remodeling, and examine occlusal characteristics and stress distribution after remodeling.MethodsTwenty-five patients who underwent premolar extraction were included in the study. The zygomatic pillar measurement range was defined, and cross-sectional areas, surface landmark coordinates, alveolar and cortical bone thicknesses, and density changes were assessed using Mimics software based on the cone-beam computed tomography scans taken before (T0) and after the treatment (T1). Multiple linear regression analysis was performed to determine the correlation between changes in the zygomatic pillar and maxillary first molar three-dimensional (3D) movement and rotation. Additionally, the correlation between pillar remodeling and occlusal characteristics was analyzed by Teetester. Pre- and post-reconstruction 3D finite element models were constructed and loaded with an average occlusal force of two periods.ResultsThe morphological and structural remodeling of the zygomatic pillar after orthodontic treatment involving premolar extraction showed a decreased cross-sectional area of the lower segment of the zygomatic pillar. The zygomatic process point moved inward and backward, whereas the zygomatico-maxillary suture point moved backward. The thicknesses of the zygomatic pillar alveolar and cortical bones were thinner, and reduced alveolar bone density was observed. Simultaneously, the movement and angle change of the maxillary first molar could predict zygomatic pillar reconstruction to a certain extent. With decreasing the total occlusal force and the occlusal force of the first molar, occlusal force distribution was more uniform. With zygomatic pillar remodeling, occlusal stress distribution in the zygomatic alveolar ridge decreased, and occlusal stress was concentrated at the junction of the vertical and horizontal parts of the zygomatic bone and the posterior part of the zygomatic arch.ConclusionsOrthodontic treatment involving premolar extraction led to zygomatic pillar remodeling, making it more fragile than before and reducing the occlusal force of the maxillary first molar and the entire dentition with stress concentrated in weak areas.Clinical relevanceNo other study has focused on the effects of orthodontics on pillar structures. The present study indicates that the mesial movement of the maxillary first molar weakened the zygomatic pillar and reduced occlusal function, thereby providing insights for inserting anchorage screws and facial esthetics.

Beyond the ARCH: Examining mandibular third molar movements in response to premolar and single incisor extractions in orthodontic practice

Mandibular third molars have been the interest of the orthodontic professionals, not only because of their Position Eruptive pattern, also because of their possible role in the development of late incisor crowding. The impaction rate of the third molars (mandible &amp;#62; maxilla) is high compared to any other teeth. The impaction incidence of M3s may be lower in patients with orthodontic premolar extraction due to mesial movement of the posterior teeth. In this study angular and positional changes of mandibular 3 molars will be evaluated with premolars as well as single incisor extraction.: This study includes 30 Pre-treatment and post-treatment orthopantomogram (OPG) of patients seeking orthodontic treatment with extractions of premolars, single incisor are categorized into 2 groups -Group I includes premolar extractions, Group II includes single incisor extractions.The study concluded that extracting premolars or single incisors did not result in improved mandibular M3 angulation on both left and right sides during the observation period.The insignificant change in angulation suggests that there are other factors that play a role in the process of alteration of third molar angulation

Three-Dimensional Evaluation of Treatment Effects and Post-Treatment Stability of Maxillary Molar Intrusion Using Temporary Anchorage Devices in Open Bite Malocclusion.

Background: We investigated treatment outcomes and post-treatment stability in 10 patients with an anterior open bite and nonsurgical orthodontics. Methods: The patients underwent maxillary molar intrusion using temporary anchorage devices (TADs) to deepen the overbite due to mandibular autorotation. Lateral cephalograms and dental cast models were obtained before treatment (T0), immediately after it (T1), and >1 year after it (T2). Skeletal and dental cephalometric changes and three-dimensional movements of the maxillary dentitions were evaluated. Results: At T0, cephalometric analysis indicated that patients had skeletal class I with tendencies for a class II jaw relationship and a skeletal open bite. During active treatment (T0 to T1), the maxillary first molar intruded by 1.6 mm, the mandibular first molar extruded by 0.3 mm, the Frankfort-mandibular plane angle decreased by 1.1°, and the overbite increased by 4.1 mm. Statistically significant changes were observed in the amount of vertical movement of the maxillary first molar, Frankfort-mandibular plane angle, and overbite. Three-dimensional (3D) dental cast analysis revealed that the maxillary first and second molars intruded, whereas the anterior teeth extruded, with the second premolar as an infection point. In addition, the maxillary molar was tipped distally by 2.9° and rotated distally by 0.91°. Statistically significant changes were observed in the amount of vertical movement of the central incisor, lateral incisor, canine and first molar, and molar angulation. From T1 to T2, no significant changes in cephalometric measurements or the 3D position of the maxillary dentition were observed. The maxillary and mandibular dentitions did not significantly change during post-treatment follow-up. Conclusions: Maxillary molar intrusion using mini-screws is an effective treatment for open bite correction, with the achieved occlusion demonstrating 3D stability at least 1 year after treatment.

Upper Midline Correction Using the Mesial-Distalslider.

The purpose of the present study is the three-dimensional (3D) analysis of molar and incisor movements that occur during the correction of the upper midline deviation by using the Mesial-Distalslider appliance. A total of 20 consecutive patients (12 women and 8 men; mean age 19.6 ± 11.1 years) were selected from the Orthodontic Department of Heinrich-Heine University of Düsseldorf. To correct the upper midline deviation (>2 mm), the patients were treated with asymmetric mechanics (mesialization on one side and distalization on the contralateral side) with the aid of Mesial-Distalslider. Dental casts were taken for each patient before (T0) and after the treatment (T1). The casts were 3D digitized and the models were superimposed on the palatal anterior region. Three-dimensional molar movements and sagittal incisor movements (proclination and retroclination) were assessed for T0 and T1. At the end of the treatment, the total movements of the molars resulted in 4.5 ± 2.2 mm (antero-posterior direction), -0.4 ± 2.4 mm (transverse direction) and 0.3 ± 0.9 mm (vertical direction) on the mesialization side, and -2.4 ± 1.7 mm (antero-posterior direction), -0.5 ± 1.5 mm (transverse direction) and 0.2 ± 1.4 mm (vertical direction) on the distalization side. Incisor displacement was 0.9 mm ± 1.7 (mesialization side) and 0.6 mm ± 0.7 (distalization side). The Mesial-Distalslider appliance could be considered a valuable tool in orthodontic treatment for upper midline correction. Within the limits of a retrospective study, asymmetric molar movements appeared possible without clinically relevant anchorage loss.

Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor ҡB, receptor activator of nuclear factor ҡB ligand, and osteoprotegerin pathway

Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement. Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n= 13) and control group (n= 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor ҡB (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry. Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P<0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P<0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P<0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P<0.05). The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Evaluating the Effects of Carriere Motion Appliance and Twin Block Appliances in Class II Correction-A Retrospective Study.

The treatment of 38 patients was assessed. Pre- and post-treatment cephalometric radiographs were analyzed to evaluate skeletal, dental, and soft tissue treatment outcomes and efficacy. Both appliances effectively corrected the Class II molar relationship. When measured at the distal aspect of the first molar, TB achieved 4.22 mm, while CMA had a 2.55 mm correction. When measured in the mesial aspect, the CMA achieved a 3.9 mm correction. The changes in SNB and ANB were statistically significant only in the TB group. The CMA appliance demonstrated statistically significantly less protrusion of the mandibular incisors and less upper incisor retrusion without vertical changes compared to the TB appliance. The TB demonstrated statistically significant lower lip protrusion compared to the CMA. The CMA corrects Class II malocclusions only by exerting a dentoalveolar influence and does not demonstrate the added effects associated with TB, such as elongation of lower facial height (LFH) and less loss of lower anchorage. Nonetheless, the correction in the TB group comprised both dentoalveolar and skeletal components. The CMA promotes a multidirectional upper and lower molar movement, and despite our 2D cephalometric analysis, we were able to estimate the extent of upper molar derotation.

Bilateral distalization of maxillary first molars in a group of adult patients after extraction of maxillary second molars using infra-zygomatic mini-implants: A prospective clinical trial

It is now possible to predictably distalize maxillary first molars in nongrowing patients with the infra-zygomatic gear distalizer and to improve malocclusions without having to extract the premolars and regardless of the patient's compliance. The purpose of this study was to investigate the amount and rate of distal movement of the maxillary first molars using our proposed appliance after extraction of maxillary second molars. Ten nongrowing female patients successfully treated with our proposed appliance were the subjects of this study. The amount, rate, and type of distalization, were analyzed through upper jaw cone beam computed tomography (pre- and post-treatment) and scanned casts taken on a monthly interval. The average amount of distalization of the maxillary first molars was 4.03 mm at the crown level and 2.88 mm at the root level. The rate of distalization had an average of 0.61 mm per month with a maximum of 0.79 mm in the first month because of the regional acceleratory phenomena after extracting the maxillary second molar. The maxillary first molars were distalized in a significant manner and all patients reached a Class I relation within an average duration of 6.4 months. The proposed appliance proved to be a viable noncompliance modality to distalize maxillary first molars correcting maxillary Class II malocclusions characterized by maxillary protrusion or maxillary incisor crowding.

Evaluating the Injection of Platelet-Rich Plasma on Second Lower Molars Protraction: A Randomized Controlled Clinical Trial.

Background The use of platelet-rich plasma (PRP) in dentistry was entered several decades ago, yet its clinical use in orthodontics still requires further investigation. The aim of this study was to evaluate the possible effects of local injection of PRP on the rate and typeof mandibular second molar protractionmovement compared with the comparator (no PRP) group. Material and methods Eighteen patients aged between 17 and 25 years were randomly allocated in a split-mouth study design to receive PRP injections on one sideimmediately before the start of molar protraction (PRP group), while the other side received only saline solution (comparator group). Eligibility criteria included bilaterally extracted mandibular first molars casesand indicated mandibular second molars protraction. The primary outcome of the study consisted of measuring the rate of molar protraction from the beginning of protraction (T0) to the end of the seventh month (TF), using a digital gauge. The secondary outcome included measuring the typeof second molar protraction movement between T0 and TFby lateral cephalometric images. Randomization of the intervention side was performed by picking out opaque sealed envelopes. The blinding of the principal investigator was impossible but blinding of the patient was achieved by injection of saline. Analyses were done using paired samples T-test to compare the changes in all variables between T0 and TF. The level of significance was taken at a P-value < 0.05. Results No significant difference was detected between the PRP and comparator groups in the rate of second lower molar protraction during seven months (0.56±0.07 mm per month in the comparator group, whereas, was 0.6±0.11 mm per month in the PRP group). Molar protraction parameters in both groups showed second lower molars moving by controlled tipping closer to bodily movement (Root Movement:Crown Movement≈0.8). Conclusions Platelet-rich plasma (PRP) is ineffective in accelerating the rate of orthodontic tooth movement (OTM) during molar protraction, and it has no effect on the type of tooth movement. In addition, the mechanics that we used (6 mm power arm in combination with miniscrews) are effective in mandibular second molar protraction by controlled tipping closer to bodily movement.

Influence of the maxillary third molars and the surrounding cortical plate during maxillary tooth movement with TADS- A CBCT Study.

To determine the influence of the presence/absence of third molars and intact/loss of cortical plate of the maxillary tuberosity on the amount of distal movement of the maxillary first permanent molar during distal movement of the maxillary dentition with mini-implants. Thirty six maxillary tuberosity sites were evaluated in eighteen young adult patients. The distal movement of the entire maxillary dentition was performed with mini-implants with 200g of distalising force applied from the mini-implant placed in the maxillary posterior buccal region to attachments placed on the arch wire between the maxillary lateral incisor and canine bilaterally. The distal movement of the maxillary first permanent molars was measured on lateral cephalograms. The maxillary tuberosity sites with intact cortical plate due to congenitally missing third molars or atraumatic extraction of third molars (G1), partial loss of cortical plate due to surgical removal of third molars (G2), fully erupted third molars (G4), third molars located at (G3), and below the cementoenamel junction (G5) were evaluated with cone beam computed tomography. One way Anova and Fisher LSD test was done. The order of greater to lesser amount of distal movement of the maxillary first permanent molar depending on the integrity of maxillary of tuberosity was partial loss of cortical plate, third molars at the cementoenamel junction, third molars below the cementoenamel junction, intact cortical plate and fully erupted third molars. The integrity of the cortical plate and the relative position of the maxillary third molar to the second molar influence the amount of distal movement of the maxillary first permanent molar during distal movement of the maxillary teeth with TADS. The amount of distal movement of the maxillary dentition appears to depend on the presence or absence of the third molars and the condition of the cortical plate in the region of the maxillary tuberosity and thereby greatly influence the outcome of treatment.

Impact of molar teeth distalization by clear aligners on maxillary alveolar bone thickness and root resorption: a three‑dimensional study

ObjectiveThis study aimed to evaluate the impact of molar teeth distalization movement by clear aligners on changes in the alveolar bone thickness and orthodontically induced inflammatory root resorption (OIIRR) in maxillary molars using conebeam computed tomography (CBCT).Materials and methodsThree-dimensional CBCT scans of 35 adult patients (one hundred forty maxillary molars) with pre-designed selection criteria and a mean age of 24.4 ± 7.1 years were included. The measured parameters, including alveolar bone thickness for maxillary molars and root resorption (OIIRR), were analyzed using pre-and post-treatment CBCT (T0 and T1, respectively) with Invivo 6.0 software.ResultPost-treatment, relevant statistically significant changes included deposition of bone in the average palatal surface of the 1st molars. The reduction of bone was seen in the average buccal surface of the first molars and both surfaces of the second molars. Regarding root length after treatment, the average maxillary 1st molar roots showed significant OIIRR (p < 0.001).ConclusionClear aligner treatment could effectively reduce the incidence of alveolar bone thickness reduction and OIIRR in treating Class II malocclusions compared to conventional braces, as shown in previous studies. This research will aid in fully grasping the benefits of clear aligners.

The Mechanics of Maxillary Molar Distal Movement Using Class II Carriere Motion Appliance: A Finite Element Study

To clarify the mechanics of tooth movement produced by a unique distalizer, Class II Carriere Motion appliance (CMA), in which the maxillary canine is connected to the maxillary first molar with a stiff bar, long-term tooth movement was simulated by the finite element method (FEM). The FEM models of the maxillary canine, premolars, and first molar were made based on a dental study model. The periodontal ligament (PDL) was constructed on the root and assumed to be a nonlinear elastic material. The teeth and the alveolar bone were assumed to be rigid bodies. The tooth moved by accumulating the initial movement produced by the elastic deformation of the PDL. When retraction force was applied to the canine from the mandibular dentition, the canine tipped or rotated clockwise and extruded due to the vertical component of the retraction force. The molar and premolars also tipped and moved distally, but hardly extruded because the vertical force did not act on them. As a result of these tooth movements, the canine protruded from the dentition. An interproximal space was created between the canine and the lateral incisor. These movement patterns were similar to those in other clinical studies using the CMA.