Lower Incisors Research Articles

Comparison of treatment effects between clear aligners and fixed appliances in patients treated with miniscrew-assisted molar distalization.

The biomechanics in achieving molar distalization may differ between fixed appliances and clear aligners in the control of tooth movement. The objective of this study was to compare the treatment effects between clear aligners (CA) and fixed appliances (FA) in patients treated with miniscrew-assisted molar distalization. The sample consisted of 46 subjects with mild-to-moderate crowding. A total of 22 patients treated with clear aligners (age, 25.66 ± 6.11 years old) and 24 patients treated with fixed appliances (age, 24.04 ± 4.95 years old) for miniscrew-assisted molar distalization were included in this study. The dental and skeletal changes were evaluated by the pre- and post-treatment lateral cephalograms. Significant changes were found with the vertical variables SN-OP angle (2.24 ± 3.22°, P < .05) and SN-MP angle (0.73 ± 1.15°, P < .05) for the FA group when compared with the CA group (SN-OP angle 0.41 ± 2.26° and SN-MP angle -0.21 ± 1.38°, P > .05). Both treatment groups achieved a 2-3mm. molar distalization with significant intrusion of the upper molars. The CA group showed significantly less distal tipping of molars (U6^PP angle -2.29 ± 3.29° and L6^MP angle -2.92 ± 2.49°, P < .05) compared to the FA group (-5.24 ± 4.28° and -5.53 ± 5.03°, P < .05). In addition, significant retraction and lingual inclination of the upper and lower incisors were found in both groups. The changes of tooth position were evaluated by 2D lateral cephalograms, not 3D measurements. Compared to fixed appliances, clear aligners seemed to have better control of vertical dimension and distal tipping of molars in patients treated with miniscrew-assisted molar distalization.

Assessment of the Alignment Acceleration of the Lower Incisors Using a Single Aligner Appliance Modified with Nickel-Titanium Coils: A Randomized Controlled Clinical Trial in Adults.

OBJECTIVE: The aim of this study was to investigate the effects of a single aligner appliance modified with nickel-titanium coils in accelerating the alignment of crowded lower incisors. MATERIALS AND METHODS: 36 patients with mild crowding of their lower incisors were randomly divided into two groups: one group received a modified aligner appliance with nickel-titanium coils (Experimental group), while the other group received traditional orthodontic brackets (Control group). The degree of irregularity in the alignment of the incisors was measured every 2 weeks using Little's irregularity index, and this was done at different time points throughout the study: before treatment (T0), after 2 weeks (T1), after 4 weeks (T2), after 6 weeks (T3), after 8 weeks (T4). RESULTS: A total of 87 patients with anterior mild crowding in the lower dental arch were initially assessed for eligibility. Out of these, 64 patients met the inclusion criteria. Eventually, 36 participants were assigned to receive the treatment. Accordingly, the data from 36 patients were analyzed statistically. There was no significant difference when comparing the two groups at T0, T1, T3, and T4. However, the difference was significant at T2 (p = 0.037). The differences were statistically significant at all time periods within each group (P &lt; 0.001). CONCLUSION: The use of a modified aligner appliance with nickel-titanium coils effectively treats lower incisors crowding, but it does not accelerate the alignment process compared to the traditional fixed orthodontic appliance.

Lower incisor position in skeletal Class III malocclusion patients: a comparative study of orthodontic camouflage and orthognathic surgery

ABSTRACT Objectives To determine the difference between orthodontic camouflage and orthodontic-orthognathic surgery using the traditional cephalometric measurement IMPA and the newly proposed IA/PAMD, the angle between the long axis of the lower incisor (IA) and the principal axis of the mandibular alveolus (PAMD). Materials and Methods This study included 40 cases each in the orthodontic camouflage group (OG) and orthodontic-orthognathic surgery group (SG). The differences between the IMPA and IA/PAMD before and after treatment were compared between the two groups. T0 lateral cephalometric images of the 10 cases with the highest and lowest increase in the IA/PAMD were analyzed to identify characteristics associated with a higher risk of overdecompensation of the lower incisors during presurgical orthodontic treatment. Results Both the OG and SG showed a significant improvement in hard- and soft-tissue measurements. However, in the OG, there was significant lingual inclination of the lower incisor but only a small change in the IA/PAMD. In the surgical group, the IMPA was close to 90° after treatment, but the IA/PAMD significantly increased. Conclusions In orthodontic camouflage, the lower anterior teeth were significantly moved lingually with a better root-bone relationship. However, this relationship deteriorated in some surgical patients. Therefore, it is important to conduct cephalometric or cone-beam computed tomography examinations during preoperative orthodontics to identify and prevent possible periodontal risks.

Increased TGF-β1 level after cocoa administration during orthodontics tooth movement in Cavia cobaya

Background: Orthodontic tooth movement (OTM) is a process of tooth movement in the alveolar socket through a bone remodeling process. Cocoa contains caffeine as a bioactive component. The number of studies on the effects of caffeine on orthodontic tooth movement is rising. Purpose: This study aimed to determine the effect of caffeine in cocoa administration on TGF-β1 levels in the pressure side during orthodontic tooth movement. Methods: Twelve Cavia cobaya were divided into 4 groups: control group (ONC), treatment group with 2.3 mg caffeine in cocoa (OWC1), 3.45 mg dose (OWC2) and 4.6 mg dose (OWC3) (n=3). A NiTi open coil spring with light force was applied to two lower incisors tooth of Cavia cobaya. TGF-β1 level in GCF of the pressure side was analyzed using ELISA on days 0, 1, 7, and 14. Data were analyzed using the Two-way ANOVA test (p&lt;0.05) and the LSD Post-Hoc test. Results: Research indicated improvement of TGF-β1 level from the control group with the least average followed group caffeine in cocoa 2.3 mg (OWC1), 3.45 mg (OWC2), and 4.6 mg (OWC3) (p&lt;0.05). Conclusion: This study confirmed that caffeine in cocoa administration increase TGF-β1 level during orthodontics tooth movement on Cavia cobaya in the pressure side.

Comparison of two-dimensional Grummons’ analysis and three-dimensional asymmetry index measurement in diagnosis of dentocraniofacial asymmetry

Background Dentocraniofacial asymmetry is a common condition that affects many individuals. Accurate diagnosis of this condition is essential for effective treatment planning. Aim This study aimed to compare the diagnosis of dentocraniofacial asymmetry using two-dimensional and three-dimensional methods. Methods A cross-sectional, observational study was conducted at the Orthodontic Specialist Clinic of the Dental Hospital Faculty of Dentistry, University of Indonesia from March to April 2023. The study included 15 patients who had not undergone orthodontic treatment and were diagnosed with dentocraniofacial asymmetry. The study compared the results of diagnosing asymmetry in 15 different facial features, including the anterior nasal spine, upper and lower first incisors, pterygomaxillary fissure, orbita, menton, porion, upper and lower first molars, coronoid process, gonion, zygoma, latero nasale, and jugulare. Results The study found that there was no significant difference in the diagnosis of dentocraniofacial symmetry between the two- and three-dimensional methods across all 15 parameters measured. The researchers used Fisher's Exact Test to compare the proportion between dependent variables and found that the p-value was greater than 0.05, indicating that there was no significant difference in the diagnosis of dentocraniofacial symmetry between the two methods. The study also used Kappa Cohen analysis to measure the strength of agreement between the diagnosis of dentocraniofacial symmetry of the two-dimensional and three-dimensional methods on each parameter. Conclusion The findings of this study suggest that both two-dimensional and three-dimensional methods are equally effective in diagnosing dentocraniofacial asymmetry. This information may be useful for orthodontists in deciding which method to use when diagnosing dentocraniofacial asymmetry.

Bimaxillary dentoalveolar protrusion associates with labially angulated mandibular canine and mesial inclined mandibular first premolars—Based on CBCT image measurements

BackgroundBimaxillary dentoalveolar protrusion is a frequent complain in orthodontic clinic. The incisor angulation and inclination have been largely discussed. The present purpose was to assess the involvement of the teeth distal to incisors. MethodsIn this cross-sectional study, 63 patients with Class I occlusion and an average sagittal relationship between the maxilla and mandible were enrolled. Twenty-two cases (20.14 ± 7.32 years old) who had protrusion profile and flaring upper and lower incisors were diagnosed as bimaxillary dentoalveolar protrusion. The other 41 cases (21.87 ± 7.15 years old) who had a balanced facial profile and mild anterior crowding were taken as controls. The buccolingual angulation and the mesiodistal inclination of the canines and premolars, which had single root, revealed on the cone-beam computed tomography (CBCT) images were measured. The values of the angulation and inclination were compared between the two groups by using Student t-test methods (α = 0.05). ResultsThe bilateral mandibular canines were more labially angulated (P＜0.001) but the bilateral mandibular first premolars were more mesial inclined in the bimaxillary dentoalveolar protrusion group than that in the control group (for tooth 34,P < 0.002; for tooth 44, P < 0.010). ConclusionsMore labial angulated mandibular canine and more mesial inclined mandibular first premolars associate with bimaxillary dentoalveolar protrusion. The labial-lingual angulation of the mandibular canines and the mesial-distal inclination of the mandibular first premolar should be paid a specially attention during the development, thus, the early intervention of the bimaxillary dentoalveolar protrusion.

Antimicrobial action, cytotoxicity and erosive potential of hypochlorous acid obtained from an electrolytic device compared with sodium hypochlorite.

This study aimed to compare the antimicrobial action, cytotoxicity, cleaning ability, and erosion of dentine of hypochlorous acid (HClO) obtained from an electrolytic device at two different concentrations (Dentaqua) and three concentrations of sodium hypochlorite (NaOCl). Microbiological test-The root canals of sixty single-rooted extracted human teeth were inoculated with Enterococcus faecalis and divided into 6 groups (n = 10), according to decontamination protocol: DW (control); 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl; 250 ppm HClO and 500 ppm HClO. The colony-forming units were counted to evaluate the decontamination potential of each group, calculating the reduction in bacterial percentage. Cytotoxicity test-Cytotoxicity was evaluated after inoculation of the same tested protocols in fibroblastic cells for 3 min, calculating the cell viability percentages. Specifical statistical analysis was performed (α = 5%). Cleaning ability and erosion-Fifty-six single-rooted bovine lower incisors were divided into seven groups of 8 roots each, being the test groups 1% NaOCl; 2.5% NaOCl; 5,25% NaOCl; 250 ppm HClO and 500 ppm HClO, and a negative and positive control. Negative control was not contaminated, and the other groups were inoculated with Enterococcus faecalis. SEM images were ranked as from the cleanest to the least clean. Erosion was also assessed, being ranked from the least to the most eroded dentine. The highest bacterial reduction was observed in experimental groups, with no statistical differences between them (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences between them (p < 0.05). 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl and 500 ppm HClO displayed the cleanest areas. All sodium hypochlorite groups displayed erosion with higher ranks with greater concentration, while hypochlorous acid did not display any erosion regardless the concentration. It is possible to conclude that HClO obtained from an electrolytic device presented high antimicrobial activity and low cytotoxicity in both tested concentrations. 500 ppm HClO did not display erosion and showed great cleaning ability. The use of 500 ppm hypochlorous acid may reduce unfavorable behavior of sodium hypochlorite whilst maintaining its antimicrobial action.

Biofilm and clinical data between volunteers with self-ligating and conventional brackets: an observational study

Introduction:  Fixed orthodontic appliances can lead to enamel demineralization and gingival changes due to increased biofilm. Aim: To detect the presence of Prevotella intermedia, Tannerella forsythia, Streptococcus mutans, Scardovia wiggsiae, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis in oral biofilm and presence of white spot lesions and gingivitis in users of self-ligating and conventional brackets. Design: This observational controlled study was conducted from January to December 2020. The participants used fixed orthodontic therapy for 6 months and were divided into a conventional and a self-ligating bracket group. The participants underwent clinical examination, and biofilm samples were collected from their lower incisors. Results: No differences were found in the bacteria detection between the groups (p&gt;0.05). However, white spot lesions were more common in users of self-ligating brackets (p=0.019). There was no association between clinical data and the detection of any microorganism (p&gt;0.05). The fluorescence intensity of A. actinomycetemcomitans was higher in self ligating brackets than in conventional brackets (p&lt;0.05). Implications: The microbial diversit did not differ between the types of brackets; however, the presence of white spot lesions and the amount of A. actinomycetemcomitans were higher in patients with self-ligating brackets.

Effects of modified twin block appliance in growing Class II high angle cases: A cephalometric study

Background Class II malocclusions represent anteroposterior dysplasia usually resulting from mandibular retrusion. Along with a retropositioned mandible, it can be associated with either upward or backward jaw rotation. High angle cases are often associated with a short ramal height, steeper mandibular plane, and large gonial angle. Twin block is a commonly used myofunctional appliance that incorporates bite planes that direct the occlusal forces in a more favorable direction for correction of the retrognathic mandible. We aimed to evaluate skeletal, dental, and soft tissue changes following modified twin block appliance therapy in high-angle cases. Methods A cephalometric study was performed on 15 growing (10-14 years) high angle (Frankfort mandibular angle 28-35°) Class II Division I malocclusion patients undergoing twin block therapy. Skeletal, dental, and soft tissue changes were evaluated by cephalometric analysis using Dolphin software. Results Pre- and post-treatment changes in cephalograms were assessed by analysis of variance and paired t-test. Significant changes in the position of the mandible (angle between Sella-Nasion-Point B [SNB] increased by 3.9 degrees, P=0.02), Wits appraisal (decreased by 1.54 mm, P=0.04), maxillo-mandibular relationship (angle between Point A-Nasion-Point B [ANB] decreased by 3.74 degrees, P=0.02) were observed. Soft tissue changes like the nasolabial angle were also significant, increasing by 3.8 degrees (P=0.04) and lower lip relation to E-line (reduction in lower lip protrusion) by 2 mm (P=0.04). Vertical parameters showed non-significant changes, like the Frankfort mandibular angle (FMA) increased by 0.07 degrees, (P=0.67), the angle between Sella-Nasion and Gonion-Gnathion (SN-Go-Gn) increased by 0.33 degrees, (P=0.67), Y-axis increased by 0.2 degrees, (P=0.32). The upper incisor inclination decreased non-significantly from 115.27±1.33 to 113.42±1.65 degrees, (P=0.12) and lower incisor increased non-significantly from 100.13±2.23 to 101.80 ±1.37 degrees, (P=0.08). Conclusions Modified twin block appliance can be used to successfully treat Class II Division I high angle cases with good vertical control.

Individualized management of chronic periodontitis in patients with orthodontic abnormalities: a clinical case report

Relevance. Chronic periodontitis is a multifactorial disease influenced by a variety of factors. Beyond periodontal pathogens and systemic conditions, important contributing factors include malocclusion, dental misalignment, and tooth loss. These conditions can compromise the tissue blood flow hemodynamics and precipitate occlusal trauma with signs of functional overload. Subsequently, this may intensify the inflammation and degradation of the alveolar bone, often leading to premature tooth loss.Correction of malocclusion is paramount in the effective management of periodontal diseases, requiring orthodontic treatment to resolve malocclusion and mitigate signs of functional overload. This treatment aims to redistribute occlusal forces uniformly, thus creating a conducive environment for successful prosthodontic rehabilitation and promoting optimal personal oral hygiene.Clinical case description. This article outlines a personalized approach to managing periodontal inflammation in individuals with orthodontic anomalies. Patient Z., born in 2002, was diagnosed with moderate severity chronic periodontitis (K05.31), presenting with a Class I molar and canine relationship on both sides, constricted dental arches, individual tooth macrodontia, and retrusion and torsiversion of the incisors. The assessment of the patient's periodontal status and overall health was conducted using standard clinical, radiographic, and laboratory diagnostics, whereas the orthodontic assessment involved anthropometric analysis of dental casts and lateral cephalometric radiographs. The periodontal intervention included foundational non-surgical treatments such as ultrasonic scaling both supra- and subgingivally, biofilm disruption using the Vector Paro system, and specific pharmacotherapy. The orthodontic treatment aimed to widen both dental arches and correct the inclination of the upper and lower incisors, achieving a normal occlusion with fixed orthodontic appliances (Damon Q brackets) in accordance with the treatment plan. The effectiveness of the treatment was measured by examining the improvement in gingival conditions, periodontal parameters, and radiographic evidence before and after the intervention.Conclusion. The research demonstrated that an individualized treatment protocol integrating periodontal and orthodontic care can substantially improve the overall health of the dentofacial complex, masticatory efficiency, and aesthetic aspects.

Effect of a novel mesh design and the sandblasting technique on the bond strength of computer-designed and three-dimension laser printed resin bonded bridges: an in vitro study

Resin-bonded bridges (RBBs) are a minimally invasive and aesthetically pleasing treatment modality. However, their frequent failure has posed challenges for both dental professionals and patients. This necessitates the exploration of innovative strategies to enhance the longevity of RBBs. This study aimed to assess the bond strength of a mesh bridge fabricated using computer-aided design and three-dimensional (3D) printing technology in comparison to the traditional aluminum oxide sandblasting method. A total of 48 lower incisors were embedded in acrylic bases according to a standardized computer-generated model to receive 24 metal RBBs. The two groups underwent distinct metal surface treatments: the 3D mesh novel design and sandblasting with aluminum oxide particles sized at 250.00 µm. The bond strength of the bridges was evaluated, and statistical analysis was performed using the independent samples t-test with a significance level set at α = 0.05. The findings revealed a significant difference between the two methods (p < 0.001). The 3D mesh design exhibited a mean bond strength of 387.89 ± 24.15 N, while the sandblasting technique yielded a mean value of 161.46 ± 31.25 N. In summary, the 3D mesh design substantially enhanced the bond strength of RBBs compared to the traditional sandblasting technique.

Severe Crowding Associated with Lower Canine Premature Resorption: Interceptive Treatment with Clear Aligners-A Pilot Study.

Early mixed dentition represents a critical phase since crowding conditions can occur. The interceptive resolution of dental crowding allows favorable arch and occlusal development. The aim of the present investigation was to evaluate dentoalveolar changes of clear aligner treatment planned to manage lower incisor crowding, loss of arch length, and midline deviation in early mixed dentition. A total of 13 patients (7 females, 6 males, 9.4 ± 1.2 age) treated with clear aligners were selected. Arch dimensions and incisor inclinations were evaluated before (T0) and at the end of interceptive treatment (T1). A paired t-test was chosen to compare T1-T0 changes. The level of significance was set at 5%. The greatest significant increase in mandibular width was observed at the level of the first deciduous molars (+2.44 ± 1.4 mm), followed by the second permanent molars (+2.16 ± 1.4 mm). Lower arch length and arch depth showed a statistically relevant increase (2 ± 0.6 mm and 4.5 ± 1.6 mm, respectively). The mean lower dental midline changes were statistically significant (1.42 ± 0.73 mm). Early treatment with clear aligners, including the combination of transversal arch development, maintenance of leeway space, and guidance of eruption, represents a valid treatment strategy in early mixed dentition to manage arch crowding and occlusion development.

Orthosurgical treatment to obtain facial aesthetics

In the present case report, a 24-year-old male underwent a combined surgical and orthodontic treatment to enhance facial aesthetics. The treatment consisted of the use of an Edgewise fixed appliance (0.022 x 0.028-in), and was complemented by a mini Wing osteotomy. The results of the treatment improved facial contours, defining and elongating the submental area, and eliminating the adipose tissue. Orthodontically, the preservation of the canines and molars Class I relationship, and the maintenance of the compensatory projection of the lower incisors were observed. Satisfactory overbite and overjet were achieved, along with a levelled curve of Spee. The combined treatment modalities led to the achievement of functional occlusion and facial aesthetics.

Prenatal and postnatal development of New Zealand white rabbit (Oryctolagus cuniculus) teeth: histological and computed tomography aspects

AbstractThe study reveals a lack of histomorphogenesis in New Zealand white rabbit teeth. The teeth development was examined through sequential histological segments in 24 rabbits from prenatal ages (E19, E21, E23, E25, and E28), neonates (E30), and postnatal age (1 week and 2 weeks); (three animal specimens at each age stage). Rabbit teeth first appeared at 19 days of prenatal life (E19) as an ectodermal epithelial thickening on each side of the mouth opening. At E21, the bud of upper incisor tooth appeared as an epithelial bud, which composed of many condensed epithelium cells, was simply identified from the larger with less condensed vestibular lamina, and was surrounded by mesenchymal connective tissue while the lower incisor took the cap stage. At (E23), tooth regular construction is formed from enamel, dentine, and pulp cavity. Peg incisor appearance (supplementary and assistant incisors) is visible at the lingual surface of the upper major incisor. Teeth prenatal development went through successive stages like initiation, bud, cap, late bell, maturation, and crown stages. The first initiation phase of tooth formation was seen as ectodermal epithelial cell collection at (E19). Bud stage saw on upper incisor tooth, while in cap structure in lower incisor teeth at (E19). A cap-formed tooth is composed of the enamel organ and fundamentally dense mesenchymal tissue. Enamel organs are segmented into three distinct layers: the external tooth enamel epithelial, the internal tooth enamel epithelial, and finally the stellate reticular layer. The cement layer covered teeth all around on enamel on both the labial and lingual sides while not contacting the dentine on the lateral side, forming enamel space. Teeth develop consistently all through life; they have expanded enamel thickness; they are diphyodont teeth; they have two continuous dentitions; they are deciduous and perpetual, with long crown teeth and an open root.

Noninvasive conservative management of anterior open bite treated with TADs versus clear aligner therapy.

Anterior open bite can be treated non-surgically via molar intrusion using temporary skeletal devices (TAD). Clear aligner therapy (CAT) is recognized as a viable therapeutic modality for non-extraction treatment of adults with mild open bite. This study aimed to compare the treatment effect and mechanisms of open bite closure between patients treated with braces and TADs double arch intrusion and those treated with CAT. Treatment success at T3 was based on 1- positive overbite on ceph; 2- Change in the vertical dimension 3- post treatment POSI score equal to zero. The TAD group includes 18 consecutively treated patients from the main author. The CAT group consisted of 16 selected patients from three different orthodontists. The observation time points were as follows: pretreatment (T1), end of molar intrusion and positive overbite achieved (T2), end of treatment (T3), at least 6-month follow-up (T4). Treatment changes were assessed by cephalometric analysis and frontal intraoral photo. At the end of treatment, 100% of the patient of the TAD group and 78,6% of the CAT group had a posi score of 0. The TAD group showed a significant reduction in vertical measurements (SN-MPA: -1,55° ± 0.41, LAFH: -3,05 ± 0.51mm, U6-PP: -1.48 ± 0.30mm), but the CAT group did not have significant changes for these variables. Both groups had significant increases in overbite from T1 to T3 (TAD: 4,32 ± 0,5mm; CAT: 2,33 ± 0.56mm), and overbite remained stable at T4. The CAT group did not have a significant upper molar intrusion, but a significant extrusion of 1.22 ± 0.42mm of the lower incisor occurred. The TAD group achieved bite closure by upper molar intrusion, lower molar and incisors vertical control, and mandibular plane counterclockwise rotation, resulting in an improved AP and vertical relationship. The CAT group achieved bite closure through the lower incisor extrusion without significant change in the vertical dimension. This study provides relevant information about the skeletal and dental changes of open bite treatment with TADs double arch intrusion. The comparison with a control group treated with CAT confirms known information.

Cross Lip Vermilion Flap and Traumatic Upper Lip Avulsion: Reducing Donor Site Morbidity.

Using a cross lip vermilion flap for upper red lip reconstruction in cases other than whistle deformity in patients with cleft lip can lead to donor site morbidity. If the practitioner performs primary closure of the mucosa in lower vermilion after flap harvesting, the width and height of lower lip are reduced, which results in an increased lower incisor tooth show. Using free fat grafting is an effective method for reducing donor site morbidity in the lower lip following cross lip vermilion flap harvest.

Evaluation of modified clear Twin Block aligner in treating adolescents with skeletal class II malocclusion: A two-centre cephalometric study.

The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre-treatment (T1) and post-treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent-sample t-test, paired-sample t-test, ANOVA test and Scheffe's Post Hoc test. Seventy-five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms-S Vert/Mi in the CTB group (P < .01) and the TB group (P < .001), as well as deep overjet through significant different in S Vert/Is-S Vert/Ii in the CTB group (P < .001) and the TB group (P < .001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance.

Tanaka-Johnston’s Mixed Dentition Analysis among Orthodontic Patients in Tanzania

Background: Lower incisors are the first teeth to erupt, their sizes are reliable and little changes occur on the lower arch during mixed dentition. These teeth can be used to predict the size of remaining unerupted teeth. Tanaka Johnston's analysis is the most widely used method of mixed dentition analysis worldwide. The aim of the study was to assess the accuracy of Tanaka-Johnston’s methods of mixed dentition analysis among orthodontic patients in Tanzania. Methods: A cross-sectional study design was carried out at MUHAS dental clinic involving models from orthodontic patients. Data collection involved actual teeth size measurement and prediction using Tanaka-Johnston’s method. Comparison between the actual measurements and the predicted measurements was assessed using students' paired t-tests. Prediction equations for the present study were generated using a simple linear regression analysis. Results: Tanaka Johnston's method significantly overestimated the combined width of upper canines and premolars in the female group (p=0.000). However, the method underestimated the lower jaw measurements in both sexes (p&lt;0.05). New prediction equations for the present study were generated for each sex and arch separately. For the upper jaw, it was Y=11.97+ 0.56X for males and Y = 10.97+0.49X for females. While for the lower jaw, it was Y= 10.8 +0.51X for males and Y=11.39+0.47X for females. Conclusion: Tanaka-Johnston’s methods of mixed dentition analysis was found to be inaccurate in estimating the size of unerupted canines and premolars in the study sample. Therefore, new prediction formulas were generated.

Influence of implant distribution on the biomechanical behaviors of mandibular implant-retained overdentures: a three-dimensional finite element analysis

ObjectiveTo assess stress distribution in peri-implant bone and attachments of mandibular overdentures retained by small diameter implants, and to explore the impact of implant distribution on denture stability.MethodsThrough three-dimensional Finite Element Analysis (3D FEA), four models were established: three models of a two mandibular implants retained overdenture (IOD) and one model of a conventional complete denture (CD). The three IOD models consisted of one with two implants in the bilateral canine area, another with implants in the bilateral lateral incisor area, and the third with one implant in the canine area, and another in the lateral incisor area. Three types of loads were applied on the overdenture for each model: a 100 N vertical load and a inclined load on the left first molar, and a100N vertical load on the lower incisors. The stress distribution in the peri-implant bone, attachments, and the biomechanical behaviors of the overdentures were analyzed.ResultsDespite different distribution of implants, the maximum stress values in peri-implant bone remained within the physiological threshold for all models across three loading conditions. The dispersed implant distribution design (implant in the canine area) exhibited the highest maximum stress in peri-implant bone (822.8 µe) and the attachments (275 MPa) among the three IOD models. The CD model demonstrated highest peak pressure on mucosa under three loading conditions (0.8188 Mpa). The contact area between the denture and mucosa of the CD model was smaller than that in the IOD models under molar loading, yet it was larger in the CD model compared to the IOD model under anterior loading. However, the contact area between the denture and mucosa under anterior loading in all models was significantly smaller than those under molar loading. The IOD in all three models exhibited significantly less rotational movement than the complete denture. Different implant positions had minimal impact on the rotational movement of the IOD.ConclusionIOD with implants in canine area exhibited the highest maximum stress in the peri-implant bone and attachments, and demonstrated increased rotational movement. The maximum principal stress was concentrated around the neck of the small diameter one-piece implant, rather than in the abutment. An overdenture retained by two implants showed better stability than a complete denture.

Hybrid Orthodontics for Aesthetic Deep Bite Correction—Case Series and General Clinical Considerations

Background: A range of psychosocial and aesthetic factors motivate patients to undergo orthodontic treatment. The appliance choice depends not only on the type of malocclusion, but also on the aesthetic and functional demands of the patients themselves. Nowadays, digital planning enables the manufacture of individualised and customised orthodontic appliances. However, the predictability of movements with aligner treatment has long been under discussion. This article illustrates, through a series of case reports, how a hybrid approach combining individualised aesthetic orthodontic appliances can improve the predictability of tooth movements, thereby providing additional tools for clinicians charged with choosing the best indicated and biomechanically advantageous technique. To this end, three patients with different malocclusions were treated via a hybrid approach involving clear aligners in the upper arch followed by lingual fixed appliances in the upper and lower arches. All patients were treated using ALIAS lingual PSL 0.018 × 0.018-inch slot brackets and in-house 3D-printed aligners. Findings: The hybrid approach combining aligners and fixed lingual appliances led to the successful resolution of all three complex cases in the series without prolonging treatment time. The superimpositions demonstrate the predictability of even traditionally difficult movements. In particular, the Alias PSL lingual system, used from the beginning, enabled good control of both the torque and inclination of the lower incisors. Conclusions: Combining clear aligners and fixed lingual appliances provides a highly efficient means of treating malocclusions aesthetically. In our cases, the aligners offset the lack of bite-plate effect from the lingual brackets and appliances, providing advantageous biomechanics for rotation correction and control of tip, torque and root movements. Understanding how to exploit the strengths of each appliance enables the clinician to treat adult patients efficaciously, efficiently and aesthetically.