Comparative evaluation of antimicrobial efficacy of various intracanal medicament in young permanent teeth: An in vivo study.

INTRODUCTION: Bacteria and their byproducts are key contributors to the onset and perpetuation of pulpoperiapical pathosis. Intracanal medication is vital in achieving successful endodontic outcomes as it targets and eradicates remaining microorganisms following biomechanical preparation. AIM AND OBJECTIVE: The aim of the study was to compare and evaluate the antimicrobial efficacy of calcium hydroxide (CH) paste, triple antibiotic paste (TAP), and probiotics (PBs) as intracanal medicament in 12-17-year-old children undergoing root canal treatment for the management of infected pulpal tissues in young permanent teeth. MATERIALS AND METHODS: A total of 30 patients aged 12-17 years indicated for endodontic therapy in maxillary incisors and with no systemic complications were selected. They were randomly divided into three groups, i.e., Group I - CH group, Group II - TAP, and Group III - PB allocating 10 teeth in each group. After access opening, the first sample (S1) was collected by inserting a paper point into the root canal, the second sample (S2) was collected immediately after biomechanical preparation, and the third sample (S3) was collected after 7 days, i.e., postintracanal medication. Samples were sent for microbiological analysis to assess the microbial count, and statistical analysis was done for the obtained data. RESULTS: The three intracanal medicaments were successful in reducing the microbial counts of Enterococcus faecalis in the infected root canals. However, according to the results of the study, the PB group demonstrated greater effectiveness against E. faecalis compared to the CH group and displayed similar antimicrobial efficacy as the TAP group. CONCLUSION: PB exhibited antimicrobial efficacy comparable to TAP but greater than Ca (OH) 2 paste. Hence, PB can be utilized as an intracanal medicament in young permanent teeth.

Effect of temperature on rehydration and fracture resistance of reattached tooth fragments after crown fracture: An in vitro study.

BACKGROUND: Uncomplicated crown fractures of maxillary anterior teeth are common dental injuries, and the bonding of fractured fragments is recommended for management. Rehydration of fragments improves bonding and fracture resistance. Therefore, the aim of this study was to compare the fracture resistance of the reattached tooth fragment of the incisor crown after rehydration using either a steamer or a humidifier. MATERIALS AND METHODS: Bovine teeth were used as a model. Fractured fragments were divided into three groups: Group I (no rehydration), Group II (rehydration by humidifier), and Group III (rehydration by steamer). Fragments were reattached using a standard bonding protocol. Fracture resistance was tested using a universal testing machine. Statistical analysis was performed using analysis of variance and Chi-square tests. RESULTS: The force required to fracture the reattached fragments was significantly higher in Group II (humidifier) compared to Group I (no rehydration) (P = 0.005). Group III (steamer) had a force value similar to Group I, indicating no significant improvement in fracture resistance with steamer rehydration. The temperature inside the steam-based chamber reached an average of 95.7°C with 95% humidity, whereas the conventional humidification chamber had an average temperature of 39.2°C and 84% humidity. CONCLUSION: Within the limitations of the present study, the rehydration protocol using a steam-based chamber was found to have a significantly lower force required to fracture the reattached fragments as compared to humidifier-based chamber. This was not significantly different from the fragments which were reattached without rehydration.

Effect of glide path preparation on the apical debris extrusion for three single-file systems.

BACKGROUND: The dentinal debris produced during root canal preparation can be extruded through the apical foramen, which may cause undesired consequences, such as the postoperative inflammation of periapical tissues. OBJECTIVES: The aim of the present in vitro study was to evaluate the effect of glide path preparation on apical debris extrusion for the Reciproc®, WaveOne Gold® and One Curve file systems. MATERIAL AND METHODS: A total of 72 mandibular incisors were divided into 6 groups according to the nickel-titanium (NiTi) system used and glide path preparation: group Rp - Reciproc; group Rp-O - Reciproc after glide path preparation; group WG - WaveOne Gold; group WG-O - WaveOne Gold after glide path preparation; group OC - One Curve; and group OC-O - One Curve after glide path preparation. The preand post-instrumentation weight of Eppendorf tubes was measured. The pre-weight was subtracted from the post-weight to calculate the amount of apically extruded debris. The data was analyzed using the one-way analysis of variance (ANOVA) with the statistical program PASW Statistics for Windows, v.18.0. RESULTS: No statistically significant differences were found between the single-NiTi file systems with different kinematics in terms of apical debris extrusion, with or without glide path preparation (p > 0.05). CONCLUSIONS: The amount of apically extruded debris was not affected by the kinematics of different single-NiTi file systems. Moreover, creating a glide path had no effect on the apically extruded debris in straight root canals.

Evaluation of apically extruded debris during root canal filling material removal in teeth with external apical root resorption: a comparison of different obturation techniques.

BACKGROUND: Root canal retreatment is necessary when initial treatment fails. Nickel-titanium systems help remove filling materials; however, some methods can cause canal content extrusion, resulting in inflammation and delayed healing. This study aimed to examine the impact of different preparation techniques and endodontic file systems on apical debris volume to limit material dispersion to periradicular tissues. METHODS: Ninety extracted maxillary incisors were evaluated. Simulated apical root resorption was created by removing the apical 2 mm of the root. The teeth were divided into two groups: one filled with a single cone and the other with cold lateral compaction (CLC). Each group was further divided into three subgroups (n = 15 each): Subgroup 1 used Reciproc R25 for removal and R50 for final preparation; Subgroup 2 used ProTaper Universal Retreatment (PTUR) files D1, D2, and D3 for removal and ProTaper Next X5 for finalization; and Subgroup 3 used VDW.Rotate Retreatment (VDW.RotateR) for removal and VDW.Rotate 50.04 for completion. Debris from retreatment was collected in pre-weighed tubes to determine the amount. The apical extrusion data underwent a two-way analysis of variance. RESULTS: The Reciproc group had a mean extruded debris weight of 0.54 ± 0.24 mg, higher than the PTUR (0.28 ± 0.15 mg) and VDW.RotateR (0.39 ± 0.29 mg) groups (p < 0.05). The single-cone technique (SCT) resulted in a mean debris weight of 0.34 ± 0.23 mg, lower than the CLC technique, which had a mean of 0.46 ± 0.27 mg (p < 0.05). SCT had a shorter retreatment duration (111.12 ± 33.46 s) compared to CLC (176.26 ± 52.26 s) (p < 0.05). CONCLUSION: The Reciproc file system and the CLC obturation technique resulted in greater apical debris extrusion than the other methods. SCT was quicker than CLC. The Reciproc groups are more susceptible to apex extrusion during retreatment.

Root canal configuration of human permanent anterior teeth: A cross-sectional study using cone-beam computed tomography in the Pakistani population.

Objectives: To analyse and document internal root morphological variations in permanent anterior teeth using conebeam computed tomography. METHODS: The cross-sectional, retrospective study was conducted from January 21 to June 19, 2021, at Jinnah Magnetic Resonance Imaging and Body Scan, and comprised data from July to December 2020 related to all the patients who had been referred to the centre for dental cone-beam computed tomography scan. The scans were evaluated at the Radiology Department of the School of Dentistry at Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan. The morphology of the roots and root canals in all permanent anterior teeth was examined. Root canal configuration was categorised using Vertucci's classification. Data was analysed using SPSS 20. RESULTS: Of the 211 patients, 116(55%) were females and 95(45%) were males. The overall mean age was 39.9±1.02 years (range: 15-65 years). All the permanent anterior teeth exhibited a single root, with the exception 2(0.9%) mandibular right and 4(1.9%) left canines which had double roots. Type I root canals were observed in all 211 (100%) maxillary right central incisors, maxillary left central incisors and maxillary left canines. Among maxillary right canines, 208(98.6%) had type-I root canals, and the corresponding value for maxillary right lateral incisors was 209(99.1%), and for maxillary left lateral incisors, the value was 210(99.5%). Root canal polymorphism had no significant association with gender (p>0.05). CONCLUSIONS: The presence of type-I root canal was common in permanent anterior teeth, and there was significant association of root canal polymorphism with gender.

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

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.

Evaluation of dentoalveolar changes following maxillary incisor intrusion with one vs two anterior miniscrews in subjects with gummy smile: a randomized clinical trial.

OBJECTIVES: To examine dentoalveolar changes following intrusion of maxillary incisors with one or two anterior miniscrews in subjects with gummy smile and deep bite. MATERIALS AND METHODS: Forty-three subjects were selected and divided into two groups: group I (22 subjects: 15 women, 7 men; mean age 30 ± 10 years) received one miniscrew between the upper central incisors, and group II (21 subjects: 16 women, 5 men; mean age 30 ± 10 years) received two miniscrews between the canines and lateral incisors. Dentoalveolar parameters, including amount of intrusion, root resorption, incisor inclination, alveolar bone thickness, and buccal alveolar crest height (cementoenamel junction to labial alveolar crest), were evaluated using cone-beam computed tomography scans obtained before and after intrusion. The intergroup comparison was analyzed using a paired t-test and unpaired t-test to determine significant changes within and between groups. RESULTS: The amount of intrusion was significantly greater in group II than in group I (P < .05). No statistically significant differences were found between groups I and II for changes in incisor inclination, labial bone thickness, and buccal alveolar crest height (P > .05). CONCLUSIONS: Maxillary central and lateral incisor intrusion was significantly greater in subjects treated with two miniscrews. Root resorption of the maxillary central incisors was notably greater in subjects with one miniscrew, while maxillary lateral incisor resorption was greater in subjects treated with two miniscrews.

Influence of Invisalign precision bite ramp utilization on deep bite correction and root length in adults.

OBJECTIVES: To assess the influence of Invisalign precision bite ramp use on skeletal deep overbite correction and root length and volume of maxillary anterior teeth. MATERIALS AND METHODS: This was a retrospective study of 60 adults with skeletal deep overbite. Patients were divided into three groups: Invisalign (Align Technology, San Jose, Calif) with precision bite ramps (Invisalign with Bite Ramps [IBR] = 12), Invisalign with no bite ramps (INBR = 22), and full-fixed appliances (FFA = 26). Cone beam computed tomography records at T1 (pretreatment) and T2 (posttreatment) were used to measure eight skeletal, nine dental, and three soft-tissue cephalometric variables. Maxillary anterior teeth root length (mm), root volume (mm3), and percent root volume loss between T1 and T2 (%) were also recorded. RESULTS: Significant changes from T1 to T2 among the three groups were seen in ANB(o), lower face height (%), ODI (overbite depth indicator) (o), and U1-SN (o). Reduction in root length was significantly less (P < .001) in the INBR and IBR groups compared to the FFA group. Reduction in root volume and percent volume loss were significantly higher in the INBR group compared to the IBR group (P < .001), but the difference between the two Invisalign groups and the FFA group was not significant. CONCLUSIONS: Skeletal deep overbite correction using Invisalign with or without bite ramps is comparable to FFA. Reduction in root length was significantly less with Invisalign compared to FFA. Bite ramps influenced root volume and volume loss but not root length.

Fluctuating arch symmetry: a comparison of two methods of assessment - applicability and efficiency.

INTRODUCTION: Symmetry is balance, some correspondence in the size, form, and arrangements of parts on opposite sides of a plane, line, or point. The opposite of this concept is asymmetry, or imbalance. OBJECTIVE: This retrospective study compared two methods for assessing arch symmetry with linear measurements based on triangles, to determine their applicability and efficiency. METHODS: Two groups were enrolled: children (n=20) and adults (n=20), and the arch symmetry was assessed from linear measurements. Method 1: the incisor-canine (INC), canine-molar (CM), and incisor-molar (INM) distances (paired t-test and Pearson correlation). Method 2: a mathematical equation between the cusps measurements of the canines and the distobuccal of the first molars leading to result 1 (t-test for one sample and bootstrapping analysis). Dental casts were digitized and analyzed using a software program. The Bland-Altman test compared the methods (α=0.05). RESULTS: The Bland-Altman test revealed concordance between the methods; however, separately the results were different: In method 1, the mandibular arch did not demonstrate correlation (children, INC r=0.33; CM r=0.45; INM r=0.51; adults, CM r=0.46; INM r=0.35), however, the maxilla revealed a strong correlation in children and a strong/moderate correlation in adults. In method 2, both arches were symmetrical (p>0.05). CONCLUSION: Method 1 may be appropriate during orthodontic treatment, and method 2 may be indicated for final treatment. These methods are useful; however, only method 1 identified the side of asymmetry. The methods can contribute to future studies in syndromic and non-syndromic patients, before and after orthognathic surgeries and orthodontic treatment, comparing results.

Root volume measurements of maxillary canines and lateral incisors in patients with unilateral maxillary canine impaction.

OBJECTIVE: This study aimed to assess root volumes of maxillary canines and adjacent lateral incisors in patients with unilateral maxillary canine impaction. METHODS: This cross-sectional study was performed on cone-beam computed tomography (CBCT) scans of 100 patients (49 females and 51 males) with unilateral maxillary canine impaction. The images were loaded in Planmeca Romexis Viewer, and root layers between the cementoenamel junction and apex were reconstructed at 600-µm intervals. At each layer, the root boundary was marked, and finally, the root volume was calculated by multiplying the layers' area by the thickness of 600 µm. The root size of canines and lateral incisors was compared between the impaction and normal eruption sides. RESULTS: Sixty-two patients showed buccal canine impaction, and 38 presented palatal impaction. The mean root volume of canines on the impaction side was significantly greater than that on the normal eruption side; either the tooth was buccally or palatally impacted (p<0.001). The lateral incisors on the side of buccally-impacted canines showed a significantly smaller root volume than that of the contralateral side (p<0.001). However, there was no significant difference in the root size of lateral incisors between the two sides in cases presenting palatal canine impaction (p=0.177). CONCLUSION: The difference in root volume of canines between the two sides can serve as an indicator of canine impaction. The reduction in the root size of the lateral incisor on the side of the buccally impacted canine may be due to root resorption created by pressure from the canine's crown.

Treatment of absent maxillary lateral incisors: orthodontic space closure and associated procedures.

Missing maxillary lateral incisors can be treated either with orthodontic space closure or preservation of the edentulous space for tooth replacement. Orthodontic space closure coupled with non-invasive post-orthodontic cosmetic dentistry is a compelling option compatible with optimal function, favourable aesthetics, and periodontal health in the long-term. We present the rationale for space closure and detail contemporary clinical strategies underpinning interdisciplinary treatment planning and excellence in finishing.

Retrospective epidemiological study of the width of maxillary diastema in patients from northeastern Bulgaria.

INTRODUCTION: A maxillary diastema (MD) is identified when the gap between the central incisors exceeds 0.5 mm. It poses an a and phonetic concern, often seen in mixed dentition and occasionally continuing into permanent dentition.

Reliability of Moyer's and Tanaka Johnston's prediction methods in a non-Caucasian heterogeneous population - a cross-sectional study.

INTRODUCTION: Mixed dentition analyses are used to determine possible tooth-size and arch-length discrepancies during the transition from primary to permanent dentition. Prediction methods using a probability table or linear regression equation use the sum of the mesiodistal widths of mandibular permanent incisors to predict the mesiodistal width of unerupted permanent teeth. Racial and sexual variations and sexual dimorphism in tooth size have been reported. The objective of this study is to validate Moyer's and Tanaka Johnston's mixed dentition analyses in a contemporary South Indian population.

Fgf9 promotes incisor dental epithelial stem cell survival and enamel formation.

BACKGROUND: Understanding the role of cytokines in tooth development is critical for advancing dental tissue engineering. Fibroblast growth factor 9 (FGF9) is the only FGF consistently expressed throughout dental epithelial tissue, from the initiation of tooth bud formation to tooth maturation. However, mice lacking Fgf9 (Fgf9-/-) surprisingly show no obvious abnormalities in tooth development, suggesting potential compensation by other FGFs. Here we report findings from an Fgf9S99N mutation mouse model, a loss-of-function mutation with a dominant negative effect. Our study reveals that Fgf9 is crucial for dental epithelial stem cell (DESC) survival and enamel formation. METHODS: To dissect the role of Fgf9 in tooth development, we performed the micro-CT, histomorphological analysis and gene expression assay in mice and embryos with S99N mutation. In addition, we assessed the effect of FGF9 on the DESC survival and dental epithelial differentiation by DESC sphere formation assay and tooth explant culture. Cell/tissue culture methods, gene expression analysis, specific inhibitors, and antibody blockage analysis were employed to explore how Fgf9 regulates enamel differentiation and DESC survival through both direct and indirect mechanisms. RESULTS: The Fgf9S99N mutation in mice led to reduced ameloblasts, impaired enamel formation, and increased apoptosis in the cervical loop (CL). DESC sphere culture experiments revealed that FGF9 facilitated DESC survival via activating ERK/CREB signaling, without affecting cell proliferation. Furthermore, in vitro tissue culture experiments demonstrated that FGF9 promoted enamel formation in a manner dependent on the presence of mesenchyme. Interestingly, FGF9 stimulation inhibited enamel formation in isolated enamel epithelia and DESC spheres. Further investigation revealed that FGF9 supports DESC survival and promotes amelogenesis by stimulating the secretion of FGF3 and FGF10 in dental mesenchymal cells via the MAPK/ERK signaling pathway. CONCLUSIONS: Our study demonstrates that Fgf9 is essential for DESC survival and enamel formation. Fgf9 performs as a dual-directional regulator of the dental enamel epithelium, not only inhibiting DESC differentiation into ameloblasts to preserve the stemness of DESC, but also promoting ameloblast differentiation through epithelial-mesenchymal interactions.

Palatal groove associated with periodontal lesions: a systematic review illustrated by a decisional tree for management.

BACKGROUND: Palatal groove represents a relatively uncommon developmental root anomaly, usually found on the palatal aspect of maxillary incisors. While its origin is controversial, its presence predisposes to severe periodontal defects. AIM: This study aimed to provide a systematic review of the literature focusing on the varied diagnostic techniques and treatment modalities for periodontal lesions arising from the presence of palatal groove. Based on the existing evidence and knowledge, the study also provides a comprehensive decisional tree, guiding clinicians in the challenging decision-making process face to a palatal groove. METHODS: The literature search was conducted on Medline and Cochrane databases by two independent reviewers, who also performed the screening and selection process, looking for English written articles reporting on diagnosis and management (all treatment approaches) of periodontal lesion(s) associated with a palatal groove. Based on this literature, a comprehensive decisional tree, including a standardized palatal groove evaluation and tailored treatment approaches, is proposed. Moreover, a clinical case is described to demonstrate the practical application of the developed decisional tree. RESULTS: Over a total of 451 articles initially identified, 34 were selected, describing 40 patients with 40 periodontal lesions associated with palatal grooves. The case report illustrates a deep, large, circumferential intra-bony defect on the palatal side of the tooth #22 associated with a shallow, moderately long palatal groove in an 18-year-old male patient. Following reevaluation, a single flap surgery was deemed necessary, combined with a regenerative procedure. At 2 years post-treatment, the tooth #22 is healthy, in a functional and esthetic position. The decision-making process, based on local and systemic patient's conditions, should allow an early and precise diagnosis to prevent further complications and undertake an adequate treatment. CONCLUSION: Palatal grooves are relatively rare; however, they are frequently associated with severe periodontal defects. The identification, diagnosis, prompt, and tailored management of the associated lesion is essential to mitigate potential periodontal and endodontic complications related to the presence of palatal groove. SYSTEMATIC REVIEW REGISTRATION: [ https://www.crd.york.ac.uk/prospero/ ], identifier [C CRD42022363194].

Periapical surgery and different root obturation protocols for upper central incisor: A finite elements analysis.

BACKGROUND: The aim of this study was to determine the effect of root canal filling using different obturation materials combined with apicoectomy in upper central incisors under loading with 1 N and 100 N. The effect of incomplete root formation was also investigated. METHODS: Based on a CBCT-scan, a model of an upper central incisor was created. The model was altered to simulate different clinical situations: root canal treatment, apicoectomy at two different lengths and with different obturation protocols, and immature root formation after trauma. In each model the tooth was loaded with 1 and 100 N, and peak Von Mises stress of bone and tooth, elastic strain of the periodontal ligament, as well as rotation and displacement of the tooth were measured. RESULTS: Periapical surgery increases stress in dentin and the surrounding bone. Different obturation materials only produce minor differences in a coronally intact tooth. CONCLUSIONS: Interincisal angle or loading direction strongly affects all measured values and needs to be considered when planning periapical surgery or comparing finite element analysis. Immature roots show the highest stress values in this study, reaching half the yield strength of dentine.

Biomechanical characteristics of maxillary anterior incisor, conventional immediate implantation and socket shield technique - A finite element analysis and case report.

BACKGROUND: To prevent the absorption and collapse of the labial bone plate of the anterior teeth, immediate implantation and socket shield technique have been increasingly applied to anterior dental aesthetic implant restoration. OBJECTIVE: To provide a biomechanical basis for implant restoration of maxillary anterior teeth, finite element analysis was used to investigate the stress peak and distribution in different anatomical sites of natural teeth, conventional immediate implantation and socket shield technique. METHODS: Three maxillary finite element models were established, including a maxillary incisor as a natural tooth, a conventional immediate implantation and a socket shield technique. A mechanical load of 100 N was applied to simulate and analyze the biomechanical behavior of the root, periodontal ligament (PDL), implant and surrounding bone interface. RESULTS: The stress distribution of the natural tooth was relatively uniform under load. The maximum von Mises stress of the root, periodontal ligament, cortical bone and cancellous bone were 20.14 MPa, 2.473 MPa, 19.48 MPa and 5.068 MPa, respectively. When the conventional immediate implantation was loaded, the stress was mainly concentrated around the neck of implant. Maximum stress on the surface of the implant was 102 MPa, the cortical bone was 16.13 MPa, and the cancellous bone was 18.29 MPa. When the implantation with socket shield technique was loaded, the stress distribution of the implant was similar to that of immediate implantation. Maximum stress on the surface of the implant was 100.5 MPa, the cortical bone was 23.11 MPa, the cancellous bone was 21.66 MPa, the remaining tooth fragment was 29.42 MPa and the periodontal ligament of the tooth fragment was 1.131 MPa. CONCLUSIONS: 1. Under static loading, both socket shield technology and conventional immediate implantation can support the esthetic restoration of anterior teeth biomechanically. 2.Under short-term follow-up, both immediate implant and socket shield technology achieved satisfactory clinical results, including bone healing and patient satisfaction. 3.The stress distribution is mainly located on the buccal bone surface of the implant and is associated with resorption of the buccal bone plate after implant replacement in both socket shield technology and conventional immediate implantation. 4.The presence of retained root fragment had an impact on the bone graft gap. In immediate implantation, the peak stress was located in the cortical bone near the implant position, while in socket shield technology, the peak stress was at the neck of the cortical bone corresponding to the retained root fragment.

Network analysis of three-dimensional hard-soft tissue relationships in the lower 1/3 of the face: skeletal Class I-normodivergent malocclusion versus Class II-hyperdivergent malocclusion.

BACKGROUND: The determining effect of facial hard tissues on soft tissue morphology in orthodontic patients has yet to be explained. The aim of this study was to clarify the hard-soft tissue relationships of the lower 1/3 of the face in skeletal Class II-hyperdivergent patients compared with those in Class I-normodivergent patients using network analysis. METHODS: Fifty-two adult patients (42 females, 10 males; age, 26.58 ± 5.80 years) were divided into two groups: Group 1, 25 subjects, skeletal Class I normodivergent pattern with straight profile; Group 2, 27 subjects, skeletal Class II hyperdivergent pattern with convex profile. Pretreatment cone-beam computed tomography and three-dimensional facial scans were taken and superimposed, on which landmarks were identified manually, and their coordinate values were used for network analysis. RESULTS: (1) In sagittal direction, Group 2 correlations were generally weaker than Group 1. In both the vertical and sagittal directions of Group 1, the most influential hard tissue landmarks to soft tissues were located between the level of cemento-enamel junction of upper teeth and root apex of lower teeth. In Group 2, the hard tissue landmarks with the greatest influence in vertical direction were distributed more forward and downward than in Group 1. (2) In Group 1, all the correlations for vertical-hard tissue to sagittal-soft tissue position and sagittal-hard tissue to vertical-soft tissue position were positive. However, Group 2 correlations between vertical-hard tissue and sagittal-soft tissue positions were mostly negative. Between sagittal-hard tissue and vertical-soft tissue positions, Group 2 correlations were negative for mandible, and were positive for maxilla and teeth. CONCLUSION: Compared with Class I normodivergent patients with straight profile, Class II hyperdivergent patients with convex profile had more variations in soft tissue morphology in sagittal direction. In vertical direction, the most relevant hard tissue landmarks on which soft tissue predictions should be based were distributed more forward and downward in Class II hyperdivergent patients with convex profile. Class II hyperdivergent pattern with convex profile was an imbalanced phenotype concerning sagittal and vertical positions of maxillofacial hard and soft tissues.

Assessment of the unwanted tooth movement associated with an extended maxillary fixed retainer (3D analysis).

BACKGROUND: Posttreatment changes after orthodontic treatment are challenging. One of the main reasons for such a phenomenon is the lack of patient compliance with removable retainers especially in the maxillary arch, due to palatal coverage, deterioration of speech, decreased masticatory efficiency, and loss of retainers. Fixed retainers have been introduced to overcome patient compliance and provide longer stable results. However, teeth still show movements when a six-unit fixed retainer is in place. Thus, in this study, an eight-unit fixed retainer was evaluated in an attempt to eliminate unwanted movements. THE AIM OF THIS RESEARCH: was to assess short-term positional changes associated with an eight-unit extended maxillary fixed retainer. MATERIALS AND METHODS: A single-arm clinical trial was conducted to address the aim of the study. This research was approved by the institutional review board of the Faculty of Dentistry, Alexandria University (IORG:0008839, No-0479-8/2022). The registration date of this study was 5/06/2023. Twenty-eight patients (19.8 ± 4.5 years) who had finished the active orthodontic phase and started retention had an eight-unit extended maxillary fixed retainer that was bonded to the palatal surface of the maxillary incisors, canines, and the first premolars or the second premolars. Pre-retention and one-year post-retention intra-oral scans were made to produce STL files that were superimposed to determine the amount of tooth change. Additionally, analysis of digital casts and lateral cephalometric radiographs was performed. RESULTS: Statistically significant changes in all planes and the rotation of teeth after one year of retention were found. The upper right lateral incisor exhibited the most evident change in the vertical plane, while the upper right central incisor exhibited the greatest change overall. Minimal changes in the cast measurements were observed. Lateral cephalometric measurements showed minimal changes after one year of retention, and these changes were not statistically significant except in the interincisal angle and the angle between the upper incisor and the line connecting the A-point to the pogonion. CONCLUSION: Increasing the extension of maxillary fixed retainers did not eliminate unwanted tooth movement in the first year of retention.