Labiolingual Direction Research Articles

Relationship Between Crown-to-Root Angulation of Maxillary Central Incisor and Lower Lip Line In Different Malocclusions

Collum angle, supplementary angle between longitudinal axis of crown-to-root, is an important consideration in patients receiving orthodontic treatment This angulation in labio-lingual direction is a key factor for proper occlusion and is greatly affected by lower lip line levels in different malocclusions. Objective: To find the relationship between collum angle of maxillary central incisor and lower lip line in patients presenting with different malocclusions. Methods: Cross-sectional, Comparative Study conducted in Orthodontics department of Nishtar Institute of Dentistry, Multan.From September 2020 to February 2021. Lateral cephalometric radiographs of 105 patients (39 males and 66 females)were selected with age range of 9-30 years. Patients were divided in 4 groups i.e Class I, Class II div I, Class II div II and class III. Collum angle was measured along with assessing lower lip-line level with central incisor. One-way ANOVA test was applied to compare level of lower lip and collum angle. Results: Mean value of collum angle was 5.82˚±5˚ for class I, 3.68˚ ± 9˚ for class II div I, 11.7˚± 5˚ for class II div II, and 6.88˚± 7 ˚for class III. Collum angle of maxillary central incisor was greatly increased in patients with class II div II malocclusion than other groups. Conclusions: Collum angle found to be highest in class II div II malocclusion group. Lower lip line resting on middle third level of maxillary central incisor crown in div II group explains this exceeding value of collum angle

Torquemeter – a simplified chair side device.

Torque enables an accurate control of the axial inclinations of teeth in a labio-lingual direction and thus, harmonise the individual tooth position relationships desirable for finished case. It is difficult to measure precisely the individual root torque incorporated in the wire without the costly and rather tedious armamentarium available in the market. Hence, an effort has been made through this clinical innovation to present a cost effective and chairside techniques to gauge the degrees of incorporated torque in the arch wire accurately

EFFECT OF FLUORIDE VARNISH CONTAINING XYLITOL-COATED CALCIUM AND PHOSPHATE ON THE REMINERALIZATION OF CARIES LIKE LESIONS IN PRIMARY TEETH

INTRODUCTION: EmbraceTM Varnish is a new fluoride varnish which contains xylitol-coated calcium and phosphate (XCP). This combination leads to increase the release time of fluoride in this varnish.Objective: To compare the remineralizing effect of EmbraceTM varnish with Profluoride® varnish on caries-like lesions in primary teeth regarding lesion depth and calcium and phosphate enamel content.Materials and methods: Fourty eight anterior primary teeth were coated with nail varnish, leaving squares of 4x4 mm then sectioned longitudinally in a labiolingual direction into two equal halves. Each half was considered as a specimen (96 specimens). Caries-like lesions were created in all specimens. Specimens were divided into two groups. group I (n=48) was subdivided into subgroup IA (n=24) treated with EmbraceTM varnish and subgroup IB (n=24) served as control, while groupII (n=48) was subdivided into subgroup IIA (n=24) treated with Profluoride® varnish and subgroup IIB (n=24) served as control. Specimens were subjected to pH cycling then they were examined with polarized light microscopy and energy dispersive X-ray spectrometer.Results: No significant difference in mean percent reduction in lesion depth following treatment with EmbraceTM varnish and Profluoride® varnish (49.51 and 45.11, respectively) at P= 0.58. Greater significant of calcium phosphate ratio was found for EmbraceTM varnish (2.25±0.43) than Profluoride® varnish (1.65±0.05) at P< 0.0001. Significance was set at the 5% level.Conclusions: EmbraceTM varnish had no significant difference in mean percent reduction in lesion depth than Profluoride® varnish, while it had a better remineralization effect than Profluoride® varnish in terms of higher mineral content.

REMINERALIZING EFFECT OF NANOHYDROXYAPATITE TOOTHPASTE ON CARIES- LIKE LESIONS IN PRIMARY TEETH (AN IN VITRO STUDY)

Objectives: To evaluate in vitro, the effect of Nano-hydroxyapatite (NHA) toothpaste in comparison with fluoridated toothpaste on remineralization of caries like lesion in the enamel of primary teeth.Materials and methods: sixty sound primary anterior teeth were coated with nail varnish; leaving squares of 3x3 mm on facial surface then 40 teeth of them were divided into two groups. Group (I) n=20 treated by NHA toothpaste and group (II) n=20 treated by fluoridated toothpaste contains sodium monofluorophosphate (1450 ppm F). They were examined with Vickers Microhardness device. The rest 20 teeth were divided into two groups (III and IV). They were sectioned longitudinally in a labiolingual direction into two equal halves, mesial half not treated (sub group IIIA) and distal half treated by NHA (sub group IIIB). Mesial half not treated (sub group IVA) and distal half treated by fluoridated toothpaste (sub group IVB). Specimens were evaluated quantitatively and qualitatively with Polarized Light Microscope.Results: The microhardness of teeth significantly decreased following acid exposure but increased again in both groups after exposure to toothpastes. The NHA toothpaste non-significantly increase percent change of microhardness by 1.65 times than Fluoridated toothpaste (p = 0.06). The percent differences in lesion depth between test group IIIB and its control group IIIA was -58.96 ± 9.04, whereas between test group IVB and its control IVA was -56.26 ± 17.43. There was no statistically significant difference between the two values (P=0.67).Conclusion: NHA and Fluoridated toothpastes are equally effective as remineralizing materials for the enamel.

A multi-patient analysis of the center of rotation trajectories using finite element models of the human mandible.

Studying different types of tooth movements can help us to better understand the force systems used for tooth position correction in orthodontic treatments. This study considers a more realistic force system in tooth movement modeling across different patients and investigates the effect of the couple force direction on the position of the center of rotation (CRot). The finite-element (FE) models of human mandibles from three patients are used to investigate the position of the CRots for different patients’ teeth in 3D space. The CRot is considered a single point in a 3D coordinate system and is obtained by choosing the closest point on the axis of rotation to the center of resistance (CRes). A force system, consisting of a constant load and a couple (pair of forces), is applied to each tooth, and the corresponding CRot trajectories are examined across different patients. To perform a consistent inter-patient analysis, different patients’ teeth are registered to the corresponding reference teeth using an affine transformation. The selected directions and applied points of force on the reference teeth are then transformed into the registered teeth domains. The effect of the direction of the couple on the location of the CRot is also studied by rotating the couples about the three principal axes of a patient’s premolar. Our results indicate that similar patterns can be obtained for the CRot positions of different patients and teeth if the same load conditions are used. Moreover, equally rotating the direction of the couple about the three principal axes results in different patterns for the CRot positions, especially in labiolingual direction. The CRot trajectories follow similar patterns in the corresponding teeth, but any changes in the direction of the force and couple cause misalignment of the CRot trajectories, seen as rotations about the long axis of the tooth.

A comparative evaluation of the sealing ability of two calcium silicate based sealers and a resin epoxy-based sealer through scanning electron microscopy and bond strength

Aim: this study aimed to compare the sealing ability of two types of commercially available calcium silicate bioceramic based root canal sealers and a resin based root canal sealer. Methods: Twenty one single-rooted teeth were used, samples (n= 21) were randomly divided into three groups according to the sealer used (group A; ADSEAL, group B; Wellroot, group C; Ceraseal). Roots were then cleaved longitudinally in the labiolingual direction; all samples were then sectioned at three, six, and nine mm from the root tip. The penetration of sealers into the dentinal tubules was examined at 1000x with a scanning electron microscope. Data were tested for normality using Shapiro Wilk test. ANOVA test was used for analyzing normally distributed data followed by Bonferroni post hoc test for pair-wise comparison. Significance level p≤0.001. Results: groups B and C showed better sealing ability than group A in all the three sections. The coronal section showed higher sealing ability than the middle section followed by the apical section in the three tested groups. Conclusion: it can be concluded that both calcium silicate-based sealers had better sealing ability and higher bond strength than the resin epoxy- based sealer.

Influence of different tooth preparation and bonding techniques on the fracture resistance of tooth fragment reattachment

Purpose comparing the influence of different tooth preparation and bonding techniques on the fracture resistance of tooth fragment reattachment. Materials and method Ninety bovine central incisors were selected. Fifteen teeth act as a control (Group A). Experimental specimens were sectioned at the mesial-incisal proximal edge 3 mm from the incisal edge in a labio-lingual direction at 25degree inclination apically. Experimental specimens were then divided into five groups according to the tooth reattachment techniques utilized; Group B: no tooth preparation + Cured bond + Flowable composite; Group C: no tooth preparation + Uncured bond + Flowable composite; Group D: Bevel + bond + Flowable composite; Group E: Over-contouring + bond + Nanohybrid composite; Group F: Over-contouring + bond + Flowable composite. Specimens were subjected to thermocycling between 5 °C and 55 °C for 500 cycles with 30 sec. dwell time. Fracture strength was evaluated using universal testing machine. Data was analyzed using One-way ANOVA. Results There was a statistically significant difference between Group A and all the experimental groups, p < .001. Group E showed the highest statistically significant fracture resistance mean value compared to other experimental groups, while the lowest mean value was found in Group B. Conclusion Though, none of the tested techniques resulted in fracture resistance similar to that of intact teeth, over-contouring technique with nanohybrid composite application showed better performances compared to the other techniques tested in the current study. Bonding plus flowable resin composite application with no additional tooth preparation and placement of a bevel are not suggested due to the low fracture strength achieved.

In-vitro evaluation of remineralization efficiency of chicken eggshell slurry on eroded deciduous enamel

OBJECTIVES: The present study evaluated the re-mineralizing efficiency of CESP on experimentally eroded deciduous tooth enamel by Claritin syrup. MATERIALS AND METHODS: 20 extracted deciduous teeth had been selected and stored in normal saline. Each tooth was cut in a labiolingual direction into 2 halves, one half used as a control and the other used as study. Demineralization of all specimens were done by twice daily immersion in Claritin syrup for ½ an hour for 12 days to form enamel erosion. Remineralization of the study group was done by using CESP slurry twice daily application for 3min. for 10 days. Surface roughness of the specimens was measured by surface profile gauge and microhardness evaluation was done using Vickers tester. Resulted data were tabulated and ana1yzed statistically by t-test with 5% significance 1evel RESULTS: There was statistically significant increase in roughness values after erosion with Claritin syrup (P<0.001). however, it was significantly decreased after remineralization (P=0.01). There was statistically significant decreased mean value of microhardness after erosion with Claritin syrup (P<0.001). however, it was significantly increased after remineralization (P=0.01). CONCLUSION: CESP slurry is a valuable topical treatment in deciduous teeth erosion since it decreased the roughness and increased the microhardness of the enamel surface in-vitro

Comparative evaluation of square and rectangular slot three-point play behavior.

The play between bracket slots and archwires affects tooth movement and the transmission of orthodontic force by multi-bracket appliances. We assessed play by quantifying the play behavior of three-point brackets and comparing the amount of play that occurred with square and rectangular slots, respectively, by using archwires of various sizes. Horizontal play with the square slot was significantly smaller than that with the rectangular slot. These data demonstrate that brackets with square slots can more effectively bring about tooth movement in the labio-lingual direction and control rotational movement with round and square archwires. Since the horizontal and vertical play ratios for the round and square wires within the square slot were approximately 1.0, three-dimensional tooth movement may also be achieved with uniform play in the vertical and horizontal directions.

ASSESSMENT OF ACCURACY OF DIFFERENT CAD/CAM FABRICATED PORCELAIN LAMINATE VENEERS

Objectives: The aim of the current study was to compare the accuracy of different restorative materials currently used in porcelain laminate veneers (PLV) fabrication, in terms of external and internal adaptation, and to evaluate the longevity of the PLV seal in response to thermocycling, in terms of microleakage. Methods: 30 (PLV) preparations were performed on maxillary central incisor to be restored with restorations fabricated by milling ceramic blocks using a CAD/CAM system. Samples were divided randomly into three groups (n=10) according to the restorative material ([Prettau, Zirkonzahn, Pustertal, Italy], [IPS e.max CAD, Ivoclar, Schaan, Liechtenstein] and VITA SUPRINITY, VITA Zahnfabrik, Bad Sackingen, Germany]). The veneers were cemented using total-etch resin cement according to manufacturer instructions, then subjected to artificial aging program after which they were immersed in basic fuchsine dye for 24 hours. All specimens were sectioned in labio-lingual direction using a precision cutting machine, and vertical gap distance, internal adaptation, and dye penetration were measured using stereomicroscope. Data were statistically-analyzed using one-way ANOVA, two-way ANOVA, Tukey’s post-hoc and Student t-tests (P≤0.05). Results: The highest statistically significant marginal gap distance and lowest internal adaptation values were recorded with Prettau group followed by IPS e.max CAD group while the lowest statistically significant marginal gap distance and highest internal adaptation values were for VITA SUPRINITY group. For the microleakage, the highest statistically significant leakage values were recorded with IPS e.max CAD group followed by Prettau group. The lowest statistically significant leakage values were for VITA SUPRINITY group. Irrespective of material’s group, it was found that incisal margin recorded statistically significant higher marginal gap distance mean values than cervical one. For the microleakage, the reverse was found. Conclusions: Under the test conditions, the following could be concluded: 1. All ceramic materials used in this study were within the clinically acceptable range of marginal accuracy. 2. CAD/CAM technology does not necessarily present highly accurate restorations, in terms of external and internal adaptation. 3. Lithium disilicate-based restorations showed better external and internal adaptation, and microleakage than monolithic Zirconia-based restorations. 4. The correlation between external and internal adaptation and microleakage is still questionable.

Fracture resistances of roots prepared with rotary files with different metal alloys and motion kinetics

Results: Statistically significant differences between groups were detected (P .05). The majority of samples were fractured catastrophically in a labiolingual direction. Conclusion: The prepared samples were more prone to vertical root fracture compared with the unprepared samples. Neither motion kinematics nor the alloys of the files significantly influenced the fracture resistances of the prepared roots.

Finite Element Analysis of Stress Distribution During Retraction of Mandibular Incisors

Aims: The present study aimed to determine stress and strain distribution on the four lower incisors under the effect of (400g) calculated retracted orthodontic force. Materials and methods: Using finite element analysis method, frictionless retraction technique was successfully used with the aid of continuous (delta loop) on NiTi, Stainless steel wires without gable bends and stainless steel looped wire using 40°. gable bends(20° alpha, 20° beta gable) respectively. Results: High compressive stress concentration in labiolingual direction are observed near the point of force application and along the line of action of orthodontic wire at the crown of both lateral and central incisors. Conclusions: The stress distribution is not the same for the all retracted segment and there was independent movement of lateral incisors from the central incisors except for the retraction using NiTi wires which exhibits uniform movements for both lateral and central incisors.

Dental macro- and microwear in Carinodens belgicus, a small mosasaur from the type Maastrichtian

AbstractTeeth of the small durophagous mosasaur Carinodens belgicus are known from Maastrichtian Atlantic-Tethyan deposits worldwide. The peculiar dentition of Carinodens inspired debate and speculation on its dietary niche ever since its first description. In this contribution, we describe the macro- and microwear pattern in five well-preserved isolated teeth, allowing further and independent evaluation of aspects of feeding behaviour and diet. Macroscopically, wear is concentrated on the apex and mesiodistal sides. Microwear was mapped using Scanning Electron Microscopy at several magnifications and can be characterised as scratches and pits. Coarse scratches were found to be the most common and pits were found to be the least common feature. Scratch orientation is primarily along the mesiodistal plane or in the labiolingual plane with an angle of ~130°. These microwear features can be explained either by oral processing or passive abrasion by sediments or food. As scratch width only indicates the minimum width of the abrading particle, the material causing the wear here could have ranged from silica-based silts to larger abrasives. However, in this case, abrasion by sediments might not explain this wear because of the biocalcarenitic nature of the type Maastrichtian sediments; siliciclastics are virtually absent. Therefore it is more likely that hard food particles, such as benthic organisms with hard exoskeletons, caused the wear on the enamel of Carinodens, or Carinodens ventured out to more sandy areas to forage as well. The mesiodistal and labiolingual direction of the microwear scratches might suggest that Carinodens showed more complexity in the use of its teeth than simple grasping, and that a gripping and pulling motion during feeding similar to that employed by modern varanids may have been the cause.

Internal adaptation, marginal accuracy and microleakage of a pressable versus a machinable ceramic laminate veneers

ObjectivesThe aim of this study was to evaluate the internal adaptation and marginal properties of ceramic laminate veneers fabricated using pressable and machinable CAD/CAM techniques. Materials and methods40 ceramic laminate veneers were fabricated by either milling ceramic blocks using a CAD/CAM system (group 1 n=20) or press-on veneering using lost wax technique (group 2 n=20). The veneers were acid etched using hydrofluoric acid, silanated, and cemented on their corresponding prepared teeth. All specimens were stored under water (37°C) for 60days, then received thermocycling (15,000 cycles between 5 and 55°C and dwell time of 90s) followed by cyclic loading (100,000 cycles between 50 and 100N) before immersion in basic fuchsine dye for 24h. Half of the specimens in each group were sectioned in labio-lingual direction and the rest were horizontally sectioned using precision cutting machine (n=10). Dye penetration, internal cement film thickness, and vertical and horizontal marginal gaps at the incisal and cervical regions were measured (α=0.05). ResultsPressable ceramic veneers demonstrated significantly lower (F=8.916, P<0.005) vertical and horizontal marginal gaps at the cervical and incisal margins and lower cement film thickness (F=50.921, P<0.001) compared to machinable ceramic veneers. The inferior marginal properties of machinable ceramic veneers were associated with significantly higher microleakage values. ConclusionsPressable ceramic laminate veneers produced higher marginal adaptation, homogenous and thinner cement film thickness, and improved resistance to microleakage compared to machinable ceramic veneers. Clinical significanceThe manufacturing process influences internal and marginal fit of ceramic veneers. Therefore, dentist and laboratory technicians should choose a manufacturing process with careful consideration.

Modal analysis of maxillary central incisor tooth

The purpose of this study was to investigate the vibration modes of tooth and explain the vibration characteristics of tooth. By using the finite element method (FEM) software, the Eigen vibration of 3-D finite element model of maxillary central incisor tooth was analyzed. Crown vibration was dominantly present in the natural modes. In general, tooth vibration was mostly dominated by the first 4 natural modes and the natural frequencies of the tooth studied were 879.65, 1286.76, 1827.21 and 2087.59 Hz, respectively. Corresponding natural mode shapes were as follows: 1st, the whole tooth vibrates along its axis in crown to root direction; 2nd, the crown swings mainly in labio-lingual direction; 3rd, the crown twists about its axis; and 4th the crown swings mainly in mesio-distal direction. The present data suggest that the modal analysis can be successfully applied in the field of study on the tooth under the loading of masticatory force. Key words: Tooth, vibration, modal analysis, frequency.

Labial access opening in mandibular anterior teeth – an alternative approach to success

Objective: To compare the conventional lingual access to labial access preparation in mandibular anterior teeth in terms of achieving a straight-line access to the apex with maximum conservation of coronal tooth structure. Method and Materials: One hundred extracted human mandibular incisors with intact crowns and patent root canal configuration were collected, numbered, and weighed in a microbalance. Each tooth was radiographed in a labiolingual direction, traced, evaluated, and assigned into 1 of 5 classes as per the classification given by Zillich and Jerome (1981).The frequency of types of canal configuration in each class was determined as a percentage. The teeth were randomly divided into 2 groups of 50 teeth. Access was prepared lingually in group 1 and labially in group 2 to achieve a straight-line access to the apex. The amount of tooth tissue lost as a result of access preparation was measured for all teeth. Results: A total of 71 teeth had their tracing projections buccal and buccoincisal. The tooth tissue lost during lingual access was significantly more than that lost during labial access preparation (P < .001). Conclusion: A labial access opening for endodontic treatment of mandibular incisors would facilitate straight-line access to canals more consistently and conservatively.

Chemical Composition and Crystalline Structure of Hypoplastic Primary Dental Enamel

The present study, reports the chemical composition of hypoplastic primary teeth examined by electron probe microanalyzer comparing with the normal part in the same tooth; and reports the X-ray diffraction results of the hypoplastic dental enamel and the normal dental enamel, and comparing the crystalline structure between the two dental enamel together with that of the synthetic hydroxyapatite. The aim of this study was to find out any change of crystalline structure. Two exfoliated hypoplastic deciduous anterior teeth were used for the electron probe study. Each tooth was sliced into two parts along the defect lesion border in a labio-lingual direction. The normal part was used as control. Determinations of weight percentage (wt%) per mass volume were made in continuous scan for P, Al, Mg, Ca, Mn, Fe, Zn, Sr, Na, K and F, from the enamel edge of hypoplastic bottom to dentin-enamel junction. Four exfoliated hypoplastic deciduous anterior teeth and eight exfoliated normal deciduous anterior teeth were used for the X-ray diffraction study. We found by X-ray diffraction that the length of the a-axis of enamel crystallite and the d-spacing (corresponding 300) were increased in the defective enamel. These could be associated with the increased content of magnesium detected by electron probe. The present study demonstrated that there were both quantity and quality changes in the enamel hypoplasia lesion, which may increase the susceptibility of the defective teeth to caries.

Perawatan Ortodontik Gigi Anterior Berjejal dengan Tulang Alveolar yang Tipis

Anterior teeth movement in orthodontic treatment is limited to labiolingual direction by very thin alveolar bone. An uncontrolled anterior tooth movement to labiolingual direction can cause alveolar bone perforation at its root segment. This case report is to remind us that alveolar bone thickness limits orthodontc tooth movement. A case of crowded anterior teeth with thin alveolar bone in malocclusion I is reported. This case is treated using adgewise orthodontic appliance. Protraction of anterior teeth is anticipated due to thin alveolar bone on the anterior surface. The conclusion is although the alveolar bone surrounding the crowded anterior teeth is thin, by controlling the movement the teeth reposition is allowed.

審美・機能的な歯列構築への追究

Expressing the individual's gender, characteristics and age is important in achieving successful dynesthetic of the mouth. Particularly, the size, color, morphology and position of the anterior teeth possessing natural harmony play important roles. The following factors are involved in establishing the esthetics of the mouth : 1) the incisal embrasures created by the occlusal plane with bilateral symmetry and the teeth with vertically harmonious axes 2) harmonious lip and buccal support produced by the teeth placed with bilateral symmetry in a buccolingual or labiolingual direction 3) harmonious vertical dimensions. Thus, a beautiful smile line is established by harmonious lip and buccal support.When examination and diagnosis of esthetic occlusion or fabrication of prostheses are performed on an articulator using an indirect method, spatial localization of the mandible and mandibular movement should also be reproduced on the articulator. To determine reference points that are common in a living body and an articulator, a face-bow transfer is generally adopted. According to the face-bow transfer, the transverse horizontal axis points are used as the posterior reference points, and the infraorbital margins are used as the anterior reference points.However, the median vertical line that is expected to reproduce the median plane of the living body are often lost during transfer, also losing the horizontal coordinates that intersect perpendicularly to the median vertical line.As is generally known, there are no esthetic indicators on the outside of the mouth reproduced on an articulator. This is clearly disadvantageous when fabricating prostheses as well as examining the following factors: the axes of the anterior teeth, bilateral symmetry of the occlusal plane, and symmetrical sagittal inclination of the occlusal plane, all of which are involved in producing a harmonious smile line most contributes to the esthetics, and bilateral symmetry of the dental arches producing harmonious lip support.Recently, an esthetic face-bow has been developed to overcome this problem. This esthetic facebow uses the median plane as common coordinates of the living body and articulator. Excellent clinical as well as laboratory results have been obtained using this esthetic face-bow in diagnosing and constructing dental arches.

Initial stress induced in periodontal tissue with diverse degrees of bone loss by an orthodontic force: Tridimensional analysis by means of the finite element method

This study was undertaken to determine the stress that appears in tooth, periodontal ligament and alveolar bone, when a labiolingual force of 100 gm is applied in a labiolingual direction in a midpoint of the crown of an inferior digitalized canine, and its changes depending on the degree of loss of the supporting bone. The analysis of tensions was carried out by means of the finite element method (FEM) for a normal case and after reducing the periodontal support bone 2, 4, 6, and 8 mm. Three-dimensional images in false color in which intensity of tensions and its areas of extension are generated. Special attention was paid to changes at level D (apical transversal section) to which maximum, mean, minimum, and Von Mises tensions are calculated. After applying the labiolingual force in the canine, a progressive increase of the stress in the labial and lingual zones of the tooth, periodontal membrane and alveolar bone was observed when the alveolar bone was reducing. In the mesial and distal zones, no compensating forces appear, which could provoke a tooth rotation during the tipping movements. (A M J O RTHOD D ENTOFAC O RTHOP 1993;104:448-54.)