Premolar Extraction Research Articles

To evaluate the divine proportion on silhouette photographs of skeletal class I bimaxillary protrusion cases treated with first premolar extraction- An in-vitro study

Objectives: The aim of the study is to assess the divine proportion of soft tissues seen in bimaxillary protrusion cases and compare this proportion on pre-treatment and post-treatment Silhouette photographs of skeletal (Sk) Class I bimaxillary protrusion patients treated by premolars extraction. Material and Methods: This research was conducted on 50 samples of pre-treatment along with post-treatment outline form photographs of Sk Class I bimaxillary protrusion patients aged 18–30 years in an orthodontics and dentofacial orthopedics department. The samples had an equal distribution with 25 males and females. All profile photos with Class I bimaxillary protrusion were converted into silhouette form. To assess the divine proportion in patient profiles, each silhouette photograph was marked by five anatomic landmarks, which were as follows: Soft-tissue nasion (N), trichion (Tr), subnasale (Sn), stomion (St), and a soft-tissue menton (Me) which was followed by the measurement of six linear dimensions; ratios were measured as R1, R2, R3, R4, and R5. These ratios of the patient’s profile, both before and after the treatment, were then compared to find out the soft-tissue alterations that have taken place in patients having Class I bimaxillary protrusion corrected by the first four premolars extraction. Results: The findings indicate that all post-treatment proportions in males indicated highly noticeable changes in contrast to pre-treatment ratios. However, females revealed highly noticeable differences in R1, R2, and R4 ratios, statistically evident differences were shown by R3 and R5 ratios in contrast to ratios before the treatment. Thus, the proportions appeared to be closer to the divine proportion. Conclusion: The results showed that all the ratios were found to be closer to divine proportion, and thus, premolars extraction in cases with convex facial form does help us to achieve esthetically pleasing faces.

Sensors: future tools for detecting young patient's stress during a dental invasive versus a non-invasive dental treatment-a pilot study.

A reliable tool to visualise children's early stress signs to prevent dental fear development is needed. The aim was to evaluate the commercially available, CE marked, Shimmer3 GSR + unit's ability to indicate for stress as a reaction of fear or pain for a non-invasive dental treatment (NI) and an invasive dental treatment (I). Patients 14-16years old were invited to undergo an oral check-up (NI) or an orthodontic premolar extraction (I), respectively. Digital data, measured via electrodes and optical pulse probe, placed on the wrist and fingers, monitored by the Shimmer3 GSR + unit, was transferred via Bluetooth to the HP-laptop. The observed digital parameters were: heart rate based on photoplethysmography (PPG), galvanic skin response (GSR), and 3-axis gyroscope and accelerometer signals for hand movements. Protocols for patient self-report scales were used: coloured analogue scale for pain intensity, facial analogue scale for the mood, and a dental fear scale. Descriptive statistics was performed. The NI-group: 20 patients, (14.6 ± 0.5years), underwent 20 oral check-ups. The I-group: 14 patients, (15.3 ± 0.5years), underwent 28 premolar extractions. All patients tolerated the Shimmer3 GSR + unit well. The GSR signal increased significantly, at start and during the oral injection, in the I-group. The GSR amplitudes persisted throughout and post the dental injection. No general uniform pattern or high GSR amplitudes were produced regarding NI-group. Considering the limitations of this study, the following conclusions can be made: the invasive treatment resulted in a specific unison GSR pattern, while the non-invasive procedure showed individually scattered GSR reactions. The commercially available CE-marked Shimmer3 GSR + device indicated the patient's stress response triggered by the invasive anaesthetic procedure.

Perception of facial esthetics and cephalometric correlations in Class II patients: a comparison between two-phase and one-phase treatments

An effective orthodontic treatment should not only aim for satisfactory occlusal outcomes but also consider its impact on facial esthetics. The study aims to evaluate and compare the perception of profile esthetics of skeletal Class II patients treated with two orthodontic modalities: (1) Two-phase approach involving functional appliances followed by fixed appliances with premolar extractions, or (2) One-phase approach using fixed appliances with premolar extractions. Additionally, the study aims to evaluate the correlation between the perceived esthetics and the corresponding cephalometric measurements. The study included 40 skeletal Class II adolescents who underwent either two-phase (n = 20, mean age = 12.38 ± 1.18) or one-phase (n = 20, mean age = 12.53 ± 0.79) orthodontic treatments. Eighty profile silhouettes (pre- and post-treatment) were assessed by 64 raters, including 23 orthodontists, 21 general dental practitioners, and 20 laypersons. The raters used a visual analog scale (VAS) to access profiles, upper and lower lips, and chin esthetics. At pre-treatment, all three groups of raters gave significantly lower scores to the profile silhouettes of the two-phase group compared to the one-phase group (P < 0.01); however, after treatment, they rated the two-phase group significantly higher (P ≤ 0.001). The two-phase group exhibited greater improvements in profile and upper and lower lip esthetics as perceived by all raters (P ≤ 0.001). Furthermore, cephalometric results revealed greater reductions in SNA, ANB, Wits appraisal, and G’-Sn-Pog’ in the two-phase group compared to the one-phase group (P < 0.05). Five cephalometric parameters (SNB, SNPog, overjet, overbite, and UL-SnPog’) demonstrated significant correlations with VAS scores given by orthodontists (P < 0.05). In conclusion, the two-phase group showed greater subjective and objective improvements in facial esthetics than the one-phase group. Additionally, the anteroposterior mandibular position and upper lip protrusion may be the primary cephalometric parameters correlated with subjective facial profile perceptions.

Closure of buccosinusal communication with rotation of a palatal flap: case report

An buccosinusal communication is an abnormal pathway between the oral cavity and the maxillary sinus. It is usually caused by surgical procedures such as the extraction of premolars and maxillary molars, due to the proximity of the roots to the floor of the maxillary sinus. The aim of this study is to report a surgical treatment for the closure of an buccosinusal communication with the advancement of a palatal flap. The patient was a 45-year-old female adult with no systemic comorbidities and no allergies. She reported pain in the left cheek and nasal discharge. Intraoral examination revealed an area of fistula in the region of element 26 measuring approximately 4-5mm. The CT scan showed a hyperdense image in the left maxillary sinus suggestive of sinus infection and a hypodense image in the region corresponding to the alveolus of element 26, suggestive of an buccosinusal communication. Initially, preoperative laboratory tests were requested and antibiotic therapy was prescribed. Intra- and extra-oral antisepsis, infiltration anesthesia were performed, fistulectomy, demarcation of the palatal flap, incision and full-thickness mucoperiosteal detachment, rotation of the palatal flap to obliterate the fistula and stabilization of the fistula using single-stitch sutures in the raw donor region with fibrin sponges under the suture, for later installation of surgical cement to help protect the wound. The patient is well, with complete closure of the communication and no evidence of post-operative complications.

Clinical Efficacy of CBCT and 3D-Printed Replicas in Molar Autotransplantation: A Controlled Clinical Trial.

To evaluate the efficacy of the combined cone-beam (CBCT)/3D-replicas protocol on the clinical and radiographic outcomes of autotransplanted molars. Controlled clinical trial registered ISRCTN13563091 from August 2019 to September 2022. Patients aged 13-22 years requiring permanent premolar extraction and having at least one non-erupted third molar were enrolled at the Institute of Stomatology, Stradins University, Riga, Latvia. Patients in the 3D-replicas (n = 30) underwent maxillary CBCT scans and had 3D-printed replicas of the third molar fabricated, while the control group (n = 28) did not. The clinical outcomes included tooth mobility, bleeding on probing, and periodontal pocket depth assessed at 3, 6, and 12 months. The radiographic outcomes included root development, obliteration, periapical status, and crown changes at 12 months. Of the 55 patients assigned to interventions, 46 completed the study. No significant differences in survival and radiographic outcomes were found between the control (n = 22) and 3D-replica group (n = 24): root development (p = 0.3), root resorption (p = 0.057), periapical status (p = 0.7), and crown/root ratio change (p = 0.4). Logistic regression showed no significant associations between radiologic predictors (root resorption: p = 0.4; periapical status: p > 0.9; root development: p = 0.8). Significant clinical outcome predictors included total operative time (β = 0.0043, p = 0.049), Moorrees' stage (stage 4: β = -0.31, p < 0.001; stage 5: β = -0.39, p < 0.001), and four donor placement times (β = 0.93, p < 0.001), but group assignment was not a significant predictor. The CBCT/3D-replica protocol showed no significant differences in the clinical or radiological outcomes. The high success rates in both groups suggest that the protocol is valuable primarily for optimizing surgical efficiency and as a training tool for clinicians.

Comparison Change of Pre and Post-Treatment in Vermilion Height and Lip Area in Adult Class II Division I Malocclusion Treated with Premolar Extraction

Aim: This study aimed to evaluate the alterations in vermilion height and lip area before and after fixed orthodontic treatment in adult patients with Class II Division I malocclusion who underwent premolar extractions. Assessments were conducted using frontal photographs and measurements from lateral cephalograms focusing on dentoalveolar and soft tissue parameters. Methods: Twenty-three adult patients with Class II skeletal malocclusion were selected from the records of the Department of Orthodontics and Dentofacial Orthopedics at AJ Institute of Dental Sciences, Mangalore. Pre-treatment and post-treatment lateral cephalograms and frontal photographs were obtained. Cephalograms were captured using a standardized KODAK 8000c digital cephalostat (69 kVp, 12 mA, 2 s), ensuring accurate patient positioning. The same investigator manually traced the cephalograms to minimize observer variability. Measurements were computed both manually and digitally for comparison purposes. Results: The study found a significant increase in the thickness from the cervical portion of the upper incisors to the upper lip after treatment (mean post-treatment: 15.77±2.28 mm; pre-treatment: 14.95±1.90 mm; P=0.006). Conversely, the thickness from the lower incisors to the upper lip decreased significantly post-treatment (mean post-treatment: 15.46±2.72 mm; pre-treatment: 17.26±2.19 mm; P&lt;0.001). Additionally, there was a significant increase in vermilion height (St-Me) and lower facial height (N-Me) after treatment, with mean differences of 3.58 mm (P&lt;0.001) and 1.18 mm (P=0.04), respectively. Conclusion: Orthodontic treatment involving premolar extractions in Class II Division I malocclusion patients led to significant soft tissue changes, particularly in lip thickness and vermilion height. Other parameters did not exhibit statistically significant differences.

Orthodontic Camouflage For Class II Malocclusion: A Case Study Using Miniscrew Implants And Strategic Extractions

This case report describes the orthodontic treatment of a 21-year-old Caucasian female patient with a Class III incisor relationship on a Class II skeletal base and increased vertical proportions. The patient presented with severe crowding in both upper and lower arches, gingivitis, molar incisors hypomineralization, and extensive caries in the LL6 tooth. She also exhibited decreased overjet, a complete overbite, and a significant shift in upper and lower dental midlines. The primary objective of treatment was to correct the malocclusion through orthodontic camouflage, which involved the extraction of upper and lower first premolars on the right side and first molars on the left. Miniscrew implants were utilized to enhance anchorage. Fixed appliances with a preadjusted MBT prescription were employed for alignment and leveling of both arches. The treatment resulted in improved occlusion, correction of midlines, and resolution of the patient’s aesthetic concerns. The case underscores the efficacy of orthodontic camouflage in managing complex malocclusion cases in adults while avoiding surgical intervention.

Evaluation of Rate of Space Closure Between Platelet Rich Plasma (Prp) Injection and Piezocision in Bimaxillary Protrusion Cases

Aim: Reducing orthodontic treatment duration is a significant concern for both patients and clinicians, as prolonged treatments can lead to complications like dental caries, root resorption, and decreased patient compliance. This study aims to compare the effectiveness of two minimally invasive techniques—Piezocision and platelet-rich plasma (PRP) injection—in accelerating orthodontic tooth movement during space closure in patients with bimaxillary protrusion. Methods: Sixteen patients diagnosed with Angle's Class I bimaxillary protrusion requiring extraction of first premolars were randomly assigned to two groups. Group A (n = 8) underwent Piezocision-assisted orthodontic treatment, while Group B (n = 8) received submucosal PRP injections. In both groups, one side of the maxillary arch served as the experimental side, and the contralateral side served as the control. Measurements of space closure were taken at the initiation of retraction (T₀) and after 90 days (T₁). Results: Both Piezocision and PRP significantly enhanced the rate of space closure compared to their control sides. However, Piezocision demonstrated a statistically faster rate of tooth movement than PRP injection. The mean difference in space closure between the Piezocision and PRP groups at T₁ was significant (p &lt; 0.001). Conclusion: While both Piezocision and PRP injections effectively accelerated orthodontic tooth movement, Piezocision proved to be more efficient in reducing treatment time. Clinicians may consider Piezocision as a preferred method for patients seeking expedited orthodontic treatment.

Effect of Collagen Plug and Bone Graft on Bone Formation in Rabbit Extraction Model

1. Purpose : This study aimed to investigate the differences in bone regeneration capacity following extraction between a control group without biomaterial placement and experimental groups where biomaterials were inserted (including xenograft, synthetic bone-containing collagen plugs, and collagen plugs).2. Materials and Methods : Bilateral extraction of maxillary first premolars or second premolars was performed, dividing the rabbits into four groups [① Group 1 :no bone graft or collagen plug inserted, ② Group 2: collagen plug inserted after extraction, ③ Group 3: collagen plug containing synthetic bone inserted after extraction, ④ Group 4: xenograft material inserted after extraction]. After euthanized the rabbit, Four and eight weeks postoperatively, the extent of bone formation were evaluated histologically and radiographically.3 Results : The degree of new bone formation using histological analysis showed higher results in both the control groups at weeks 4 and 8, although not statistically significant. Across all groups, higher bone formation was observed at 8 weeks compared to 4 weeks. In radiological analysis using micro CT, Bone Mineral Density (BMD) and Bone Volume/Tissue Volume(BV/TV) were highest in Group 4. Trabecular bone thickness(Tb.Th) was highest in the control group, but not statistically significant.4. Conclusion : In all groups, the degree of new bone formation at 4 and 8 weeks did not show statistically significant differences histologically and radiologically.

Osteoinductively Functionalized 3D-Printed Scaffold for Vertical Bone Augmentation in Beagle Dogs.

To evaluate the efficacy of 3D-printed scaffolds that were osteoinductively functionalized with a bone morphogenetic protein 2 (BMP-2)-incorporated biomimetic calcium phosphate particles (BMP-2-inc. BpNcCaP)/hyaluronic acid (HA) composite gel in vertical bone augmentation in beagle dogs. Four Beagle dogs were used in this study. Three months after the extraction of 1st, 2nd, 3rd, and 4th premolars at both sides of the lower jaws of Beagle dogs, one or two critical-size vertical bone defects (4 mm vertical bone defect without buccal and lingual bone) on each sidewere surgically created. The defects were randomly subjected to the following groups: (1) Control (without bone-defect-filling materials); (2) 3D scaffold; (3) BMP2-inc. BpNcCaP/HA-functionalized 3D scaffold. Six weeks post-surgery, samples were harvested and subjected to micro-CT and histomorphometric analyses. The struts of the BMP2-inc. BpNcCaP/HA-func. 3D scaffold were covered by a thick layer of cemented irregular particles with an average pore size at 327 ± 27 μm. The BpNcCaP/HA-func. 3D scaffold group bore significantly higher bone volume, bone volume fraction, trabecular number, trabecular thickness, bone mineral density, connectivity density, and bone volumes in three directions (mesiodistal, buccolingual, and apicocoronal) when compared with the groups of Control and 3D scaffold. Moreover, the BMP2-inc. BpNcCaP/HA-func. 3D scaffold group bore significantly lower trabecular separation and exhibited significantly higher bone-to-scaffold contact percentage and newly formed bone area percentage within pores in comparison with 3D scaffold. BMP2-inc. BpNcCaP/HA-func. 3D scaffold dramatically enhanced vertical alveolar bone augmentation, which suggests a promising application potential of BMP2-inc. BpNcCaP/HA-func. 3D scaffold in dental clinic.

Favourable dentoalveolar changes after lower premolar extractions for Class III camouflage with completely customized lingual appliances

BackgroundThe aim of the investigation was to evaluate if the inclination of the lower anterior teeth can be controlled reliably after lower premolar extraction for Class III camouflage treatment with completely customized lingual appliances (CCLAs). Treatment outcome was tested against the null hypothesis that lower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will lead to further compensation by retroclining mandibular incisors during CCLA treatment.MethodsThis retrospective study included 25 patients (f/m 12/13; mean age 20.7 years, SD 9.5 years) with uni- or bilateral Class III molar relationship and a Wits value of ≤ -2 mm. In all consecutively debonded patients, lower premolars were extracted to correct the sagittal relationship with a non-surgical camouflage approach. Lateral head films prior to (T1) and at the end of lingual orthodontic treatment (T2) were used to evaluate skeletal and dentoalveolar effects. A paired t-test with alpha = 5% was used to define differences between the endpoints. The linear correlation between the inclination of the mandibular incisors at T1 and the achieved correction was measured with the Pearson correlation coefficient (PCC). A Schuirmann’s TOST equivalence test was used to check if the final lower incisor inclination was within the defined norms.ResultsThe null hypothesis was rejected as the mean lower incisor inclination was improved by 1.8° despite lower premolar extractions (T1: 86.8°/ T2: 88.6°). There was a strong correlation (-0.75) between the lower incisor inclination at T1 and the achieved correction indicating a controlled correction towards the norm regardless of the initial incisor position. At T2, the interincisal angle as well as the lower incisor inclination were within the norm.ConclusionLower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will not lead to undesired retroclining of mandibular incisors during CCLA treatment even in severe cases.

Anchorage loss of the posterior teeth under different extraction patterns in maxillary and mandibular arches using clear aligner: a finite element study

BackgroundExtracting the premolars is an effective strategy for patients with bimaxillary dentoalveolar protrusion. Clear aligners (CAs) close the extraction spaces through shortening the length of aligners. The contraction force generated by the terminal of aligners makes the posterior teeth tip mesially, which is known as the roller coaster effect. This phenomenon is even worse in the 2nd premolar extraction cases. Posterior anchorage preparation is commonly used to protect the angulation of molars, taking the form of presetting distal tipping value. However, the distal tipping design aggravates the anchorage loss of anterior teeth simultaneously. This study aimed to explore the different anchorage loss of the posterior teeth when the 1st or 2nd premolars were extracted using CAs, respectively in maxillary and mandibular arches, further providing guidance for anchorage preparation design in clinical practice.MethodsTwo bimaxillary finite element models with different extraction patterns were established to simulate the anterior en-masse retraction process of the CAs. In Model 1, the maxillary and mandibular 1st premolars were extracted, while in Model 2, the 2nd premolars were extracted. Finite element analysis methods were utilized to analyze the tipping angle of the anterior and posterior teeth.ResultsCompared between two models, the anterior teeth exhibited a greater lingual inclination tendency and the posterior teeth exhibited a slighter mesial tipping tendency in Model 1 regarding individual tooth. The closer to the extraction spaces, the greater the tip, and the distal tipping tendency of the 1st premolars was more evident than the mesial tipping tendency of the 1st molars in Model 2. Compared between the maxillary and mandibular arches, the mesial tipping tendency of individual posterior tooth was more evident in the maxilla. In addition, the highest hydrostatic stress of the periodontal ligaments was concentrated on the cervical and apical parts directly adjacent to the extraction spaces, and it exhibited relatively uniform distribution in Model 1.ConclusionsThe individual posterior tooth showed the same mesial tipping direction but to different degree when the 1st or the 2nd premolars were extracted during clear aligner treatment. Presetting anchorage preparation design for the posterior teeth is essential to alleviate the roller coaster effect, especially in the 2nd premolar extraction cases. Furthermore, larger anchorage preparation value should be proposed for the maxillary posterior teeth.

Assessing position changes of impacted third molars in treatment of class II malocclusion with premolars extraction.

Third molars (M3) remaining impacted in Class II malocclusion characterised with sagittal mandibular deficiency is a high probability. The null hypothesis of this study is that mesioangular M3s changes position through the eruption way inClass II malocclusion treatmentrequiring moderate anchoragewith four first premolars extraction.The aim of this study is to reconsider the decision to surgically extract impacted third molars in four premolars extraction treatment of Class II malocclusion. The materials consisted of the pre-treatment and post-treatment lateral cephalograms and orthopantomographs of 30 individuals with skeletal and dental Class II malocclusion with a mean chronological age of 13.48 years, who were treated by the same clinician (H.G.) with four first premolar extractions via the straight wire technique at the Ankara University Faculty of Dentistry Department of Orthodontics, Ankara, Turkey. The sagittal position of the upper and lower incisors and molars, M3position and M3space were evaluated with the paired-t test; the relationship between the sagittal position of the upper and lower incisors and molars and the change in M3position were evaluated with correlation analysis. Results: The study found the retroclination and mesial movement of the upper incisors and molars, and an increase in the M3space by the fixed orthodontictreatment. An insignificant steepening of both the upper right M3position and the lower right M3position was found. A statistically significant increase in the lower right and left side M3spaces was found. Positive correlations between lower right M3angulation and the sagittal position of the lower incisors and first molars were found. Improvement in the mesioangulation of the M3s and an increase in the M3space were achieved in this study. Based on the findings, it is useful to review the decision for prophylactic surgical extraction of the M3s before orthodontic treatment in such cases, taking into account the risks of postoperative complications.

Periodontal Ligament Reactions to Orthodontic Force: A Transcriptomic Study on Maxillary and Mandibular Human Premolars.

Orthodontic force (OF) induces a variety of reactions in the periodontal ligament (PDL) that could potentially account for individual variability regarding orthodontic tooth movement (OTM). This study investigates the transcriptomic profile of human PDL tissue subjected to OF invivo for 7 and 28 days, additionally comparing the differences between maxillary and mandibular PDL. Healthy patients requiring orthodontic premolar extractions were randomly assigned to one of three groups: control (CG) where no OF was applied, 7 days and 28 days, where premolars were extracted either 7 or 28 days after the application of a 50-100 g OF. Total RNA was extracted from the PDL tissue and analyzed via RNA-seq. Differentially expressed genes (DEGs) were identified using a false discovery rate and fold change threshold of < 0.05 and ≥ 1.5 respectively. Functional and Protein-Protein Interaction analysis were performed. After 7 days of OF, the reaction of PDL to OF is characterized by cell responses to stress, increased bone resorption, inflammation and immune response, and decreased bone formation. In contrast, after 28 days, bone regeneration is more prominent, and processes of bone homeostasis, immune response, and cell migration are present. The response of maxillary and mandibular PDL was different. Bone resorption was observed in the maxilla at 7 and 28 days, while in the mandible expression of cell proliferation and transcriptional activity were predominant after 28 days of OF. The early reaction of the PDL to OF corresponds with increased bone resorption and decreased bone formation. After 28 days, bone formation became more prominent. The maxillary and mandibular PDL present asynchronous responses during OTM. These findings enhance our comprehension of the mechanisms underlying the origin-specific responses of PDL to different lengths of OF, which is potentially relevant in the development of personalized therapeutic strategies.

Three-dimensional assessment of alveolar bone changes and root resorption in extraction patients after fixed orthodontic treatment: A prospective study

The aim of this study was to evaluate the alveolar crestal bone height, alveolar bone thickness, and root resorption in mandibular incisors after fixed orthodontic treatment. A total of 35 patients (mean age 17.02 ± 3.24 years) with moderate to severe mandibular anterior crowding requiring first premolar extraction were included. Cone beam computed tomography scans of the mandibular anterior region were obtained from the patients before and after orthodontic treatment. The alveolar crestal bone height, cortical bone thickness (CBT) (at apex and midroot level), labial and lingual alveolar bone thickness, and root resorption were assessed for all mandibular incisors. Paired Student's t test was used to compare pretreatment and post-treatment alveolar bone changes and root resorption. A significant decrease in lingual crestal bone height was observed in all mandibular incisors after orthodontic treatment (P < 0.001). Lingual CBT decreased at the midroot level significantly for all mandibular incisors after completion of orthodontic treatment (P < 0.001). A significant decrease in total lingual bone thickness was observed in all mandibular incisors (P < 0.001). Root lengths of mandibular incisors decreased significantly in the sagittal and coronal sections after orthodontic treatment (P < 0.001). Fixed orthodontic treatment with premolar extraction results in a significant reduction of alveolar crestal bone height, CBT (at midroot level), and alveolar bone thickness on the lingual aspect of mandibular incisors. Significant orthodontically induced inflammatory root resorption was observed in all mandibular incisors after orthodontic treatment.

Lip and incisor changes in patients with different ethnicities treated with extraction versus nonextraction: A cone-beam computed tomography study

This study used cone-beam computed tomography (CBCT) via voxel-based superimposition to evaluate lip and incisor changes after orthodontic treatment with four premolar extractions (Ext) versus nonextraction (Non-Ext) among African American (AA) and White (W) patients. A total of 240 CBCTs of 120 adolescent orthodontic patients with Class I skeletal/dental relationships were included. Patients were initially divided according to treatment, and then each group was subdivided according to patients' ethnicity (Ext/W = 30, Ext/AA = 30, Non-Ext/W = 30, and Non-Ext/AA = 30). CBCTs were imported into Invivo6 for voxel-based superimposition. Lip and incisor measurements were recorded. Independent t tests and two-way ANOVA were used for statistical assessment. The Non-Ext/W group had a greater increase in all outcome variables compared with the Non-Ext/AA group, with a significant change in volume and position of upper (UL) and lower lips (LL), inclination of upper (U1) and lower incisors (L1), and position of U1. The Ext/AA group had a greater decrease in all measured outcomes compared with the Ext/W group, with significant change in inclination of U1 and L1, and position and volume of LL. W patients had more crowding than AA patients in both treatment approaches. Retraction ratios of 6.5:1 and 2.1:1 were recorded between the U1 and UL positions, and L1 and LL positions, respectively. There were no direct interaction effects between ethnicity and treatment, nor were there any significant effects of ethnicity after controlling for the covariates. Ethnicity alone has no impact on incisor and lip position after treatment. However, ethnicity in the form of initial presentation of malocclusion can have a significant influence.

A Cephalometric Study Of Vertical Skeletal Changes After Extraction And Non-Extraction Fixed Orthodontic Treatment Of Class I Malocclusion In North Indian Population

Background: Orthodontic treatments frequently involve tooth extractions to address crowding and protrusion, but the effects of these extractions on vertical skeletal changes are still debated. Research has extensively covered aspects like soft tissue response and smile aesthetics, yet there is no consensus on their impact on vertical dimensions. This issue is particularly pertinent for hyperdivergent individuals, who make up about 22% of orthodontic patients. A proposed technique for such cases includes counterclockwise rotation of the lower jaw and advancement of posterior teeth to manage open bites or excessive vertical facial height. This study aims to compare vertical skeletal changes in Class I malocclusion patients undergoing extraction versus non-extraction fixed orthodontic treatments. Material and Methods: We analysed pre- and post-treatment lateral cephalometric radiographs from 60 Class I crowding patients, evenly split into extraction and non-extraction groups. Eight vertical skeletal parameters were assessed and compared statistically between the two groups. Superimposition analysis of radiograph tracings was used to explore vertical changes related to molar mesialization, particularly in the extraction group. Results: The extraction group demonstrated significant reductions in vertical skeletal dimensions compared to the non-extraction group. Measurements including FMA, SN-GoGn, Y-axis, SN-PP, and PP-MP showed significant differences, with reductions in the extraction group (P = 0.001). Procrustes superimposition indicated effective molar mesialization in the extraction group, which was not observed in the non-extraction group. Conclusion: Extraction of first premolars in fixed orthodontic treatment leads to a notable decrease in vertical skeletal dimensions, in contrast to the slight increase seen with non-extraction treatments. This reduction is largely due to molar mesialization, which enhances vertical skeletal dimensions and treatment stability in Class I crowding cases.

Effects of Attachment Design and Aligner Material on Mandibular Canine Distal Bodily Movement in Aligner Treatment

Abstract Purpose Dental crowding is a result of a mismatch between tooth size and arch dimensions, which leads to malocclusion; treatment often involves premolar extraction before orthodontic alignment. Clear aligners are limited in their ability to achieve canine distal bodily movement, a common orthodontic maneuver. This study investigated the impacts of attachment design and aligner material on the efficacy of canine distal bodily movement. Methods A finite element analysis was conducted to examine the impact of various attachment designs and two aligner materials, thermoplastic polyurethanes/polycarbonate (TPU/PC) and polyethylene terephthalate glycol-modified (PETG), on mandibular canine distal bodily movement. The investigation focused on the biomechanical responses in the periodontal ligament (PDL) and surrounding alveolar bone. Results Attachment configuration exerted a strong influence on mandibular canine movement. Vertically oriented attachment pairs positioned mesially (mesial occlusal–mesial cervical) resulted in the most effective canine distal bodily movement, followed by a rectangular attachment. TPU/PC aligners induced slightly higher principal stresses in the PDL and von Mises stress and strain in the surrounding alveolar bone compared with PETG aligners; however, the difference was negligible, amounting to less than 6%. Conclusion Attachment design, specifically vertically oriented pairs positioned mesially (mesial occlusal–mesial cervical), was determined to be the crucial factor influencing the efficacy of canine distal bodily movement. The choice of aligner material (TPU/PC or PETG) has minimal impact on this orthodontic procedure.

Evaluation Of Lateral Root Resorption In Maxillary Teeth Among First Premolar Extraction Cases After Space Closure- A CBCT Study

Background: Orthodontic treatment usually involves usage of light continuous forces but when heavy forces are used it leads to apical root resorption. External apical root resorption refers to reduction in root structure involving the apices. This resorption is of transient inflammatory type. 2D images are commonly used for diagnostic purposes in orthodontics but it cannot detect root resorption on lingual or buccal surfaces thus cannot measure the volume of root loss. Cone beam computed tomography which can provide 3D images was introduced in late 1990s. Images provided by CBCT are more more accurate than panoramic and periapical radiographs . Therefore in this study , CBCT is used to evaluate lateral root resorption in maxillary teeth after after space closure among first premolar extraction cases . Materials and Methods: CBCTs of 20 patients fulfilling inclusion and exclusion criteria were taken before the start of orthodontic treatment and after space closure. Post treatment root width was substracted from the pre treatment root width at three levels from CEJ (3mm,6mm,9mm). The normality test (Shapiro-Wilk Test) was performed to analyze the data, and the results were expressed as frequency with percentage and mean with standard deviation. Difference between means were assessed using paired t test for before and after the procedure. All the statistical analyses were carried out at a 5% level of significance, and results with a P value &lt; 0.05 were considered statistically significant. Results: Considering all the three levels the least tooth resorption was observed in the case of central incisor (0.1750 ± 0.0444, p &lt;0.001) and highest in the canine tooth (5.900± 0.0000, p &lt;0.001) . Conclusion: When root resorption is detected, it is recommended to pause the treatment for about 6 months to allow for root repair. Intermittent forces, which provide rest periods between applications, are more tissuefriendly and can help reduce the risk of further resorption

Does enamel deproteinisation with 10% papain affect shear bond strength of orthodontic adhesives: a randomised controlled trial.

To evaluate the effect of 10% papain as an enamel deproteinising agent on the shear bond strength (SBS) of three orthodontic adhesives: Transbond XT, resin-modified glass ionomer cement (RMGIC) and Biofix. Single-centre, double-blinded, split-mouth randomised controlled trial. Department of Orthodontics and Dentofacial Orthopaedics, Nair Hospital Dental College, Mumbai, India. A total of 20 participants requiring bilateral premolar extraction for fixed orthodontic treatment in both the maxillary and mandibular arches were included in this study. In total, 80 premolars from the above-mentioned participants were divided into four groups as follows: group A: Transbond XT deproteinised with 10% papain gel; group B: Biofix deproteinised with 10% papain gel; group C: RMGIC deproteinised with 10% papain gel; and group D: Transbond XT without enamel deproteinisation as a control group-bonded as instructed by the manufacturer. After deproteinisation, brackets were bonded and after a follow-up period of 28 days, the teeth were extracted. The SBS was then measured using the Universal Testing Machine. The force needed to shear the bracket was documented, and bond strengths were subsequently calculated in megapascals (MPa). The obtained results were subjected to statistical analysis and one-way ANOVA was performed to compare the mean SBS between the groups. Subsequently, pairwise comparisons were conducted using Tukey's post hoc test. There was a statistically significant difference in SBS among all groups (P = 0.002). The SBS of TransXT with deproteinisation increased significantly compared with TransXT without deproteinisation (P = 0.03). There was no statistically significant difference between the SBS of TransXT without deproteinisation and RMGIC (P = 0.47) and Biofix (P = 0.39), both with deproteinisation. The use of 10% papain for deproteinising enamel improved the SBS of all materials. Deproteinising improved the SBS of RMGIC and Biofix to the level of TransXT without deproteinisation.