Axis Of Tooth Research Articles

Numerical simulation of optimal range of rotational moment for the mandibular lateral incisor, canine and first premolar based on biomechanical responses of periodontal ligaments: a case study.

The objective of this study was to investigate the optimal range of rotational moment for the mandibular lateral incisor, canine and first premolar to determine tooth movements during orthodontic treatment using hydrostatic stress and logarithmic strain on the periodontal ligament (PDL) as indicators by numerical simulations. Teeth, PDL and alveolar bone numerical models were constructed as analytical objects based on computed tomography (CT) images. Teeth were assumed to be rigid bodies, and rotational moments ranging from 1.0 to 4.0 Nmm were exerted on the crowns. PDL was defined as a hyperelastic-viscoelastic material with a uniform thickness of 0.25 mm. The alveolar bone model was constructed using a non-uniform material with varied mechanical properties determined based on Hounsfield unit (HU) values calculated using CT images, and its bottom was fixed completely. The optimal range values of PDL compressive and tensile stress were set as 0.47-12.8 and 18.8-51.2 kPa, respectively, whereas that of PDL logarithmic strain was set as 0.15-0.3%. The rotational tendency of PDL was around the long axis of teeth when loaded. The optimal range values of rotational moment for the mandibular lateral incisor, canine and first premolar were 2.2-2.3, 3.0-3.1 and 2.8-2.9 Nmm, respectively, referring to the biomechanical responses of loaded PDL. Primarily, the optimal range of rotational moment was quadratically dependent on the area of PDL internal surface (i.e. area of PDL internal surface was used to indicate PDL size), as described by the fitting formula. Biomechanical responses of PDL can be used to estimate the optimal range of rotational moment for teeth. These rotational moments were not consistent for all teeth, as demonstrated by numerical simulations. The quantitative relationship between the area of PDL internal surface and the optimal orthodontic moment can help orthodontists to determine a more reasonable moment and further optimise clinical treatment.

Construction reproducibility of a composite tooth model composed of an intraoral-scanned crown and a cone-beam computed tomography-scanned root.

ObjectiveTo evaluate the construction reproducibility of a composite tooth model (CTM) composed of an intraoral-scanned crown and a cone-beam computed tomography (CBCT)-scanned root.MethodsThe study assessed 240 teeth (30 central incisors, 30 canines, 30 second premolars, and 30 first molars in the maxillary and mandibular arches) from 15 young adult patients whose pre-treatment intraoral scan and CBCT were available. Examiner-Reference (3 years’ experience in CTM construction) and Examiners-A and Examiner-B (no experience) constructed the individual CTMs independently by performing the following steps: image acquisition and processing into a three-dimensional model, integration of intraoral-scanned crowns and CBCT-scanned teeth, and replacement of the CBCT-scanned crown with the intraoral-scanned crown. The tooth axis angle in terms of mesiodistal angulation and buccolingual inclination of the CTMs constructed by the three examiners were measured. To assess the construction reproducibility of CTMs, intraclass correlation coefficient (ICC) assessments were performed.ResultsThe ICC values of mesiodistal angulation and buccolingual inclination among the 3 examiners showed excellent agreement (0.950–0.992 and 0.965–0.993; 0.976–0.994 and 0.973–0.995 in the maxillary and mandibular arches, respectively).ConclusionsThe CTM showed excellent construction reproducibility in mesiodistal angulation and buccolingual inclination regardless of the construction skill and experience levels of the examiners.

Effect of building-up core material’s kind on location of fracture for endodontically treated teeth restored using glass Fiber post (in-vitro study)

Introduction: The quality of the material used to build-up the cores of the treated and restored teeth with fiberglass posts affect the location of fracture, as it plays an important role in the durability and durability of the coronary root restoration under different oral environment conditions. The aim of the study: Study of the effect of the core building-up material quality of three different materials on the location of fracture for a group of lower premolars after treating the core and restoring them with fiberglass posts. Research materials and methods: The research sample consisted of (30) lower first laughs, as these teeth were extracted in the course of orthodontic treatment (free from any defects) and stored with distilled water. The clinical crowns of these teeth were cut so that a coronary tissue was kept 2mm high above the enamel-cemento junction. These teeth were treated with pulp and restored with fiberglass posts. The research sample was divided into three groups, each consisting of (10) premolars, according to the type of core building-up material. 1. Composite Resin (IVOCLAR, T-Econom, Liechtenstein) Group T. 2. Flow composite resin (IVOCLAR, Titric N-Flow, Liechtenstein) Group F. 3. Resin Reinforced Glass Ionomer Cement (3M ESPE, Vitermer, USA) Group G. The teeth were crowned with Nickel-Chrome crowns and then an oblique force was applied at an angle of 45 to the tooth axis using a general mechanical testing device at a speed of 1mm / min until failure occur. Results: It was found that group T premolars restored with composite resin had nine Cervical Fracture states and once in middle while the locations of fracture fore premolars restored with Flow resin had eight Cervical Fracture states and twice in Middle, and locations of fracture for premolars Restored with Glass ionomer cement had ten Cervical Fracture, and significant differences were observed between groups (P =1). Conclusion: As it turns out, there is no correlation to the core building-up material in the failure model.

Effect of different surface treatment protocols on bond strength to root dentin using bulk fill restorative material

Evaluate the influence of different surface treatment protocols on the bond strength of bulk fill restorative material to root dentin using the push-out test after cyclic loading. Forty intact human premolars, freshly extracted for orthodontic purpose with straight canals and fully developed apices, were selected for this study. The coronal portion of the teeth were cut perpendicular to the long axis of the teeth at the cement-enamel junction. All root canals were instrumented, cleaned, and obturated; then, a space of 3 mm in depth was prepared below the orifice level in both canals in each tooth to receive direct core bulk fill material; the specimens were classified according to the surface treatment protocol into four groups (n = 30). Group 1: no surface treatment (control group); group 2: surface treatment using Er,Cr:YSGG laser; group 3: surface treatment using chlorhexidine; and group 4: surface treatment using 17% EDTA solution. Restorations were bonded using universal adhesive following the same protocol. The roots were sectioned and three 1-mm-thick slices were obtained representing the length of the restorations inside the canals. The specimens were thermocycled, then subjected to push-out testing. A specimen from each group was examined using scanning electron microscope. Data was analyzed statistically using Kruskal-Wallis test and pairwise comparisons were carried out. The results showed that laser group was significantly higher than EDTA and chlorhexidine groups, and also higher than the control group with no significant difference. Also, the control group was significantly higher than EDTA and chlorhexidine group. However, chlorhexidine group was higher than EDTA group with no significant difference recorded (p < 0.05). Er,Cr:YSGG laser showed promising results in terms of bond strength to radicular dentin. But still the control group using universal adhesive can provide comparable and satisfactory results.

Evaluation of Shears Strength of Dowel Amalgam and Post-amalgam in Root Canal-treated Teeth

Introduction: Amalgam, which can be applied with or without dowel, is one of the commonly used restorative materials for core restoration in pulpless teeth. The current study aimed to compare the shear strength of amalgam cores with and without dowel. Methods: A total number of 20 recently extracted mandibular premolars were assigned to two groups of 10 equal specimens, including group I: dowel amalgam restored with prefabricated dowel and amalgam core and group II: post-amalgam restored with amalgam as a post and core. All Specimens were stored at humidity and room temperature prior to testing. Each specimen was carefully placed in a special jig at a 90-degree angle to the axis of teeth and subjected to a load that was recorded in kgf on a Zwick/material testing machine at a crosshead speed of 0.5 mm/min until failure. Independent T-test was used to compare the results. Results: Based on the obtained results, the mean shear strengths were reported as 37.7±10.49 and 16.8±6.37 kgf for dowel amalgam and post-amalgam, respectively. There was a statistically significant difference between the two groups (P<0.0001). Conclusions: The obtained results demonstrated a significant difference between the two groups. Accordingly, the use of dowel with amalgam to restore pulpless teeth has higher compressive strength, as compared to the use of post-amalgam

MORPHOLOGICAL FEATURES OF MUCOUS MEMBRANE OVER IMPACTED TEETH DEPENDENING ON CONDITIONS OF THEIR POSITION

Impacted teeth are rather common and complex dentofacial anomaly, which requires a balanced approach not only in differential diagnosis of its specific nosological form, but also in a choice of rational treatment methods. Taking into account the multi-factor nature of conditions formation for delay of teeth eruption, an approach to treatment should be directed towards guiding links of pathogenesis.&#x0D; The aim of the study is to increase effectiveness of surgical and orthodontic treatment of patients with impacted teeth of anterior maxillary region by studying morphological features of mucous membrane over impacted teeth, depending on conditions of their positioning.&#x0D; A group of 21 individuals aged from 15 to 17 years was formed to evaluate objectively the results of our work. Clinical situation in all the patients was the same according to diagnostic criteria as presence of impacted maxillary canines and medium level of vertical depth of impaction (in alveolar process); root formation: completely formed, with deviation of longitudinal axis of impacted tooth from correct axis of eruption from 15º to 45º. During further analysis, clinical subgroups were identified depending on conditions of impacted teeth positioning in vestibular-oral direction.&#x0D; Moderate dystrophic changes in stratified squamous epithelium, moderate sclerotic changes in papillary layer of lamina propria were found based on findings of microscopic structure of mucous membrane over palatal positioning of teeth.&#x0D; During investigation of morphological structure of mucous membrane over labially positioning of impacted teeth, there were phenomena of hyperkeratosis, an increase in the number of intraepithelial lymphocytes, presence of epithelial cells in the basal layer with signs of hydropic degeneration. In papillary layer of lamina propria of mucous membrane, sclerotic changes were observed, which were more pronounced in comparison with palatal positioning of impacted teeth.&#x0D; Complex analysis of results of morphological studies showed that in mucous membrane positioning over impacted teeth there is deterioration with anemia in filling conditions of microcirculatory bed, discirculatory disorders, which leads to formation of ischemic zones and development of dystrophic and sclerotic processes.&#x0D; Morphological features of the structure of mucous membrane over impacted teeth is an important to consider while planning surgical and orthodontic treatment, and to some extent, it is possible to adjust management tactics of such patients, taking into account labial or palatal positioning of impacted teeth.

Surgical Orthodontic Treatment in Case of Severe High Angle Skeletal Class II Malocclusion and Mandibular Retrusion.

This report describes a patient with severe high angle class II malocclusion and mandibular retrusion in whom surgical orthodontic treatment to prevent an increase in ramus height resulted in a significant improvement in esthetics and long-term stability. The patient was a woman aged 30 years 5 months who presented with the chief complaint of maxillary protrusion. She had a convex facial type, a chin button on lip sealing, and a gummy smile. Cephalometric analysis revealed a normal maxilla anterior-posterior position, but significant mandibular retrusion with pronounced clockwise rotation. The anterior maxillary tooth axis was standard, but labially inclined in the mandible. Based on these findings, the diagnosis was skeletal class II high angle malocclusion and mandibular retrusion. The proposed treatment plan comprised 2-jaw surgery with premolar extraction. Le Fort I osteotomy, in particular, was planned in the maxilla to move the ANS upward by 3.0 mm and the PNS downward by 3.0 mm. Sagittal split ramus osteotomy (SSRO) was planned to adjust the mandible and move the mandible forward by 10.0 mm. To prevent postoperative relapse, the short lingual split method was used in performing the SSRO. The mandible was split to minimize stretching of the median pterygoid muscle. Postoperatively, the ANS, PNS, and pogonion showed movement of 2.0 mm upward, 3.0 mm downward, and 8.0 mm forward, respectively. Additionally, lip closure was now natural, and the gummy smile had markedly improved. At 6 years postoperatively, there has been no change skeletally or dentally. Follow-up is being continued to monitor further progress.

Estimation of three-dimensional long axes of the maxillary and mandibular first molars with regression analysis

The purpose of this study was to determine the long axes of molars with multiple roots through ordinary least squares regression (LSR) and to compare them with the axes defined by principal component analysis (PCA). Three-dimensional radiological images of 20 dry skulls were obtained by cone-beam computed tomography (CBCT). Data from maxillary and mandibular first molars were extracted from the CBCT DICOM data with a three-dimensional image visualization system. The obtained data were reconstructed, converted to STL files, and three-dimensional coordinate values were extracted. The long axes were estimated by an algorithm to synchronize the LSR line with the horizontal axis which was translated to the vertical axis. The axes of the molars defined by LSR were compared with the axes of the molars defined by PCA. The coordinate point number of each molar was 5400–5800. The algorithm for determining the tooth axes in this study consisted of four stages containing three steps each. The distance between the two axes calculated by the two methods (LSR and PCA) on the horizontal plane through the origin was less than 10−12 mm and the deviations between them were less than 0.003°. The long axes of the molars estimated by LSR agree almost exactly with the axes estimated by PCA, and the accuracy is sufficient for clinical usage; however, the distance between them would shorten with a more severe convergence condition of the α value at each stage of this LSR system.

Anthropometric Analysis of Mental Foramen in Dry Human Mandibles in Karnataka

Abstract Background and Objectives The mental foramen which is located on the anterior surface of the mandible is a bilateral opening transmitting mental nerves and vessels that supply important structures around. However, it is reported that the location of mental foramen varies across different races and genders, the awareness of which is vital in surgical interventions, anesthetic applications, and various other invasive procedures. Hence, the objectives of the present study were to study the location, size, and shape of mental foramina in dry human mandibles and to study the incidence of accessory mental foramina in human mandibles. Materials and Methods One hundred eighty dried mandibles were observed for the location, size, and shape of mental foramen. Digital Vernier calipers were used to measure the distance of right and left mental foramen from various locations like alveolar crest, symphysis menti, lower border of mandible, and posterior border of the ramus of mandible. The data were analyzed using SPSS 20 software. The position and number of accessory mental foramen were determined. Results The various positions of mental foramina studied revealed the most common type to be type IV as per the Tebo and Telford classification. The average horizontal diameter was slightly higher than the average vertical diameter in majority of the bones. Accessory mental foramina were observed in 3 mandibles. Conclusion The mental foramen was most commonly situated along the longitudinal axis of second premolar tooth and the shape of the mental foramen was found to be oval in 95% of the bones studied.

Herausforderungen und Lösungsansätze bei der Diagnostik einer Wurzelquerfraktur im Röntgenbild

ObjectivesDiscussion of the importance of X-ray diagnostics in dental traumatology and requirement of multiple X-ray images in different axes for sufficient diagnostics.Clinical procedureThe 11-year-old patient showed up in the emergency unit of the dental clinic in Erlangen in April 2018 around 9 pm, approximately 2 hours after crashing in a slide in a public swimming pool. After detailed examination of the tooth 11 a root-crown-fracture with involvement of the pulp was diagnosed. The fragments of the tooth 11 were partially present but could not be joint together in order to restore the crown. The X-ray taken in occlusal view before emergency treatment did initially not show any abnormalities or fractures. No movement of the crown could be found, the tooth was tender to percussion and did not react to testing of sensibility. Emergency treatment included documentation via photographs and detailed information of the treatment steps: local anaesthesia was followed by a micropulpotomy using calcium hydroxide. Further dentine defects were capped using composite. The patient showed up in the dental clinic the following day complaining about slight pain (regio 11). The tooth was still tender to percussion and not reacting to testing of sensibility. An orthopantomogram for further examination of the temporomandibular joint showed a root fracture in the apical third of tooth 11. This diagnose was confirmed via another small X-ray using a different angle vertical to the tooth axis. The patient and her mother were informed about further treatment options (root canal treatment of the coronal part of the root, MTA plug) and the questionable outcome of tooth 11.Conclusions for practiceIn order to perfectly diagnose or exclude root fractures after dental trauma X-rays using different axes should be taken. Also, a high resolution cone beam computed tomography (CBCT) can be considered for further examination in complex cases.

FEATURES OF DIAGNOSTICS AND TREATMENT OF IMPACTED TEETH (A LITERATURE REVIEW)

Research rationale. Impacted teeth are those that remain partially or completely in the bony tissue or under the mucous membrane for 2 years after the term of their physiological eruption. The issues of the impacted teeth diagnostics, clinical manifestations and treatment features in young children have been studied according to the literature sources data; the significant rate of impacted mandibular third molars (up to 22%), maxillary third molars (up to 18%) and maxillary canines (4%) has been determined.&#x0D; The presence of impacted teeth requires a thorough diagnostics and a balanced approach to the choice of treatment method; the latter depends on the clinical situation, the patient’s age and general somatic status.&#x0D; With the right choice of treatment method, the success of restoring the integrity of the dental arch, aesthetics and function is significant.&#x0D; Objective: an analysis of literature sources regarding the issues of clinical manifestations, diagnostics and treatment of maxillary and mandibular impacted teeth in young people.&#x0D; Presentation of the main material. A literature review demonstrated the presence of a significant number of impacted teeth classifications based on clinical data; part of the classifications was based on modern x-ray studies (CBCT - Cone beam computed tomography). Many research works on resorption of the teeth roots located next to the impacted ones have been analysed; a variety of methods for treating dental retention has been reviewed.&#x0D; Conclusions and their discussions. Impacted teeth remain rather common pathology in young people, which requires a balanced approach to the diagnostics and to the choice of treatment method, as only correct management of such patients can lead to beneficial result. In the examination algorithm it is mandatory to establish the position of the impacted tooth axis in the jaw and in relation to the adjacent teeth axis; the condition of the alveolar bone, the age of the patients and their general somatic status are also of great importance.&#x0D; The choice of treatment method, such as orthodontic, surgical and combined, with the additional use of periodontal surgery and physiotherapy treatment should be individual, followed by monitoring and regular medical check-up.

Analysis of whether or not the alveolar palatine bone thickness of the central incisors is sufficient for implants of 3 mm and 3.5 mm thickness using Cone-Beam Computed Tomography

Objective: The purpose of this study was to investigate the alveloar palatine bone thickness of the maxillary central incisors using cone-beam computed tomography (CBCT).&#x0D; Material and Methods: This study used the CBCT images of 480 patients (240 male – 240 female). In order to determine bone thickness, measurements were made on the program perpendicularly to the long axis of the tooth at 3 points selected from the 3, 6 and 9 mm apical or the enamel-cement border in parallel to the long axis of the central teeth.&#x0D; Results: For the left central teeth, the mean palatine bone thickness was found for the coronal, medial and apical regions as 1.48 mm, 3.09 mm and 5.13 mm, respectively, while these values were respectively 1.35 mm, 2.95 mm and 5.10 mm for the right side.&#x0D; Conclusion: Considering that there should be a bone of at least 1 mm thickness on socket walls for immediate implantation, it was determined that palatine bone thickness is not sufficient by itself for immediate implantation. As a result of the analysis, it was seen that the palatine alveloar bone thickness that was observed in women was thinner than that in men.&#x0D; &#x0D; How to cite this article: Üner DD, İzol BS. Analysis of whether or not the alveloar palatine bone thickness of the central incisors is sufficient for implants of 3 mm and 3.5 mm thickness using cone-beam computed tomography. Int Dent Res 2019;9(2):51-7.&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Molar inclination and surrounding alveolar bone change relative to the design of bone-borne maxillary expanders: A CBCT study.

To evaluate the molar inclination and skeletal and alveolar bone changes when comparing tooth bone-borne (MSE) and tissue bone-borne type maxillary expanders (C-expander) using cone-beam computed tomography (CBCT) in late adolescence. A sample of 48 late-adolescent patients were divided into two groups according to the type of expander: MSE group (n = 24, age = 19.2 ± 5.9 years) and C-expander group (n = 24, age = 18.1 ± 4.5 years). CBCT scans were taken before treatment and 3 months after expansion. Transverse skeletal and dental expansion, alveolar inclination, tooth axis, buccal alveolar bone height, thickness, dehiscence, and fenestration were evaluated on the maxillary first molar. Paired t-test, independent t-test, Pearson's chi-square test, and Spearman correlation analysis were performed. The MSE group produced greater dental expansion (P < .05), whereas skeletal expansion was similar in both groups (P = .859). The C expander group had more alveolar bone inclination change (P < .01), and the MSE group had more buccal tipping of the anchorage teeth (P < .01 or .001). Buccal alveolar bone height loss and thickness changes were greater in the MSE group (P < .01 or <.001). Formation of dehiscences was more frequent in the MSE group (P < .001), whereas for fenestrations, there were no significant differences between the two groups. Buccal bone height loss in the MSE group had a negative correlation with initial buccal bone thickness. The incorporation of teeth into bone-borne expanders resulted in an increase in the severity of side effects. For patients in late adolescence, tissue bone-borne expanders offer comparable skeletal effects to tooth bone-borne expanders, with fewer dentoalveolar side effects.

Cone-beam computed tomography digital for measuring the inclination angle to the long axis of healthy maxillary anterior teeth and morphologically characterizing their labial bone plates

We aim to determine the thickness of the labial plate, the distance between the cement-enamel junction (CEJ) and alveolar crest, and the inclination angle of the long axis of healthy maxillary anterior teeth by using cone- beam computed tomography (CBCT). A total of 345 CBCT volumes obtained by Newtom VGI® CBCT were analyzed by using the NNT software. The digital measurements of the labial bone plate thickness at level 4 mm below the CEJ, the midpoint of tooth root and the radiological tooth apex, the distance between the CEJ and alveolar crest, and the angle between the long axis of the teeth and the long axis of alveolar process were obtained from the mid-sagittal planes of maxillary incisors and canines. Plate thickness 4 mm below the CEJ was measured, and values below ≥1 mm were recorded. In the central incisor, 1) the angle between the long axis of the teeth and alveolar bone was 15.2°±6.2°, the distance between the CEJ and alveolar crest was (1.5±1.0) mm, labial bone plate thick-ness at 4 mm below the CEJ was (0.8±0.4) mm, the midpoint of tooth root was (0.6±0.4) mm, and the radiological tooth apex was (1.3±0.7) mm; in the lateral incisor, 16.2°±8.8°, (1.6±1.0) mm, (0.7±0.5) mm, (0.4±0.6) mm, and (1.1±0.7) mm, respectively; and in the canine, 19.0°±6.2°, (1.8±1.0) mm, (0.9±0.6) mm, (0.4±0.6) mm, and (1.2±0.7) mm, respectively. 2) The frequencies of plate thickness ≥1 mm were 28.3%, 25.8%, and 42.7% in the central incisor, lateral incisor, and canine, respectively. 3) The distance between the CEJ and alveolar crest was positively correlated with age. The correlation coefficients was 0.42 (P<0.01) in the central incisor, 0.50 (P<0.01) in the lateral incisor, and 0.62 (P<0.01) in the canine. The thickness of labial bone plate is thin, the distance from CEJ to alveolar crest increases with age, and the long axis of the teeth is more inclined than the long axis of alveolar process. Knowledge of these special morphological characteristics can improve the safety and result for many dental procedures.

Randomized controlled study of the effectiveness of osteopathic manipulative correction for muscular torticollis due to birth injury

Introduction.Muscular torticollis (MT) is the most common lesion of the musculoskeletal system in children, ranking third in pediatric practice. There are references in the literature confi rming high effi cacy of manipulative therapy, but in Cochrane′s 2015 Annual Review, experts did not fi nd evidence of the effectiveness of the manipulations. We carried out research in order to determine the effectiveness of osteopathic manipulative correction (OMC) in children with muscular torticollis (MT) due to birth injury (code for ICD X: P 15.8).Goal of research— to study the gradual effectiveness of OMC on the basis of clinical and instrumental studies and ultrasound examination of the relationship between the bone structures and the cervical muscles.Materials and methods.57 children aged 0–7 years with muscular torticollis due to birth injury were examined. All patients were randomly divided into 2 groups. Patients of the main group (32 children) received osteopathic treatment. Each child received from 3 to 5 sessions, depending on the severity of the birth injury and the duration of postural disorders. The time gap between the sessions was 2–3 weeks. Patients of the control group (25 children) received physiotherapy, massage and orthosis every day for 2 weeks. Along with the neurological examination the study of the effectiveness of treatment included assessment of the pain syndrome with the use of the behavioral numerical scale FLACC, and the assessment of the muscle tone with the help of the kinesthetic examination. Angle of rotation in the cervical spine was measured with the use of the goniometer. Moreover, all children underwent sonography of the cervical spine in order to determine the position of the tooth axis, with the calculation of the coeffi cient of asymmetry. The state of the musculus rectus capitis major (MRCM) and musculus sterno cleido mastoideus (MSCM) was also assessed.Results.It was observed that after OMC the clinically signifi cant improvement started earlier in patients of the main group. This improvement manifested by complete elimination or signifi cant reduction of biomechanical and tone disorders in the neck. Pain syndrome, measured with the help of the FLACC scale, signifi cantly decreased both after treatment and in catamnesis after 6 months (p0,05). When intercomparing left and right muscles in the groups, signifi cant differences were revealed (p0,05).Conclusion.The use of OMC (3 to 5 treatment sessions with the intervals of 2–3 weeks) in patients with MT is more effective than the treatment with the use of physiotherapy, massage and orthotics, which was received by patients every day for 2 weeks. This allows to recommend OMC for wider clinical use in this category of patients.

Three-dimensional finite element analysis of the composite and compomer onlays in primary molars

Resin onlay restoration is an esthetic alternative technique used for restoring extensively damaged primary molars. Understanding the behavior of materials under repeated functional stress and how the stress is transmitted to the remaining tooth structure is important. The aim of this study was to compare stresses in primary molars restored with indirect composite and compomer onlay. 3D frame models of the right mandibular and maxillary primary molars and the alveolar bone were created using computerized tomography images of a six-year-old girl. The enamel and dentine layers above the cement layer were unified to generate onlay restoration, and composite and compomer were used as restorative materials. The vertical occlusal load (100 N) was applied to the teeth in the occlusal contact areas. The von Mises stress distributions and normal stress distributions of the y-axis (parallel to the long axis of tooth) were evaluated. The occlusal stress is transmitted to the cervical part of healthy teeth by spreading it through the enamel layer. The composite and compomer restorative materials exhibited similar stress distribution patterns. An indirect technique creates a structure similar to the original morphological form, and it allows restorations to distribute high occlusal stresses and to minimize possible breakages.

Clinical and Radiographic Assessment of Periodontal Infrabony Defect Depth and Width and Their Correlation

Brief Background There is preliminary evidence of periodontal defect depth, number of walls and the width of infrabony defects exerting influence on the regenerative potential of particular therapeutic modality. Aim: To assess defect width and defect depth and their influence on pretreatment defect angle in patients affected with periodontal disease. Materials and Methods 60 untreated severe chronic or aggressive periodontitis patients were selected for the study. Digital intraoral periapical radiograph of defects in all patients were taken using RVG. First auxiliary line was drawn to represent tooth axis (AUX1). Perpendicular to this, a second auxiliary line (AUX2) was drawn that ran through most coronal margin of defect (M3). The depth of defect was measured as the distance between the base of bony defect and AUX2. The width of defect was the distance from coronal margin of bony defect to the root surface perpendicular to AUX1. Results In a total of 67 defects, the radiographic defect depth, defect width and defect angle for maxillary arch was 3.19 ± 1.19 mm , 2.82 ± 0.63 mm and 37.34 ± 9.47 ° respectively while these values for mandibular sites were 3.69 ± 0.92 mm, 2.87 ± 0.76 mm and 35.62 ± 7.08 ° respectively. Multilevel regression analysis revealed narrow defect angles to be related to deep infrabony defects, whereas the width of the interdental space to wide defects. Summary and Conclusion Defect dimensions are determined by the radius of action of microbial biofilm and the baseline defect angle of an infrabony defect would be a function of defect depth. Key Words: Periodontitis, periodontal therapy, vertical defects, radiography

Influence of Varying Ferrule Heights and Configurations on the Fracture Resistance of Endodontically Treated Mandibular First Molars-An in Vitro Study

Purpose: To evaluate the influence of varying ferrule heights and configurations on the fracture resistance of endodontically treated teeth restored with custom cast post and cores and full metal crowns. Method: Fifty extracted human mandibular first premolars were randomly divided into 5 groups: I, no root canal treatment (RCT), crown; II, no post and core, crown; III, 2-mm ferrule, cast post and core and crown; IV, non-uniform ferrule (2 mm buccal and lingual, 0.5 mm proximal), cast post and core and crown; and V, no ferrule, cast post and core and crown. Samples were subjected to a static load on the buccal cusp, 150° to the long axis of the tooth, and failure load was recorded. Statistical analysis was carried out with a 1-way analysis of variance and the Bonferroni pairwise comparison. The mode of fracture was noted by visual inspection. Results: Absence of ferrule resulted in significantly lower fracture resistance (V: 308.27 +/- 75.567 N) as compared to all other groups. Group I: 714.69 +/- 89.37 N, and Group II: 656.90 +/- 133.15 N were significantly more resistant as compared to Group IV: 471.98 +/- 115.99 N (p < 0.01). However, there was no significant difference between non-uniform ferrule and the uniform 2-mm vertical ferrule. Conclusion: The premolars with a ferrule were more fracture resistant as compared to the teeth with no ferrule preparation.

Palatal en-masse retraction of segmented maxillary anterior teeth: A finite element study

ObjectiveThe aim of this finite element study was to clarify the mechanics of tooth movement in palatal en-masse retraction of segmented maxillary anterior teeth by using anchor screws and lever arms.MethodsA three-dimensional finite element method was used to simulate overall orthodontic tooth movements. The line of action of the force was varied by changing both the lever arm height and anchor screw position.ResultsWhen the line of action of the force passed through the center of resistance (CR), the anterior teeth showed translation. However, when the line of action was not perpendicular to the long axis of the anterior teeth, the anterior teeth moved bodily with an unexpected intrusion even though the force was transmitted horizontally. To move the anterior teeth bodily without intrusion and extrusion, a downward force passing through the CR was necessary. When the line of action of the force passed apical to the CR, the anterior teeth tipped counterclockwise during retraction, and when the line of action of the force passed coronal to the CR, the anterior teeth tipped clockwise during retraction.ConclusionsThe movement pattern of the anterior teeth changed depending on the combination of lever arm height and anchor screw position. However, this pattern may be unpredictable in clinical settings because the movement direction is not always equal to the force direction.

A new evaluation method of three-dimensional tooth axis and dental arch using cone-beam computed tomography

A new evaluation method of three-dimensional tooth axis and dental arch using cone-beam computed tomography