Om Prakash Kharbanda

Dental and skeletal changes after intraoral molar distalization with sectional jig assembly.

The present study was conducted on 10 subjects to evaluate dental and skeletal changes after intraoral molar distalization. The maxillary molars were distalized with a sectional jig assembly. Sentalloy open coil springs were used to exert 150 gm of force for a period of 12 weeks. A modified Nance appliance was the main source of anchorage. The pre- and postdistalization records included dental study casts, clinical photographs, and cephalograms. A total of 665 readings recorded from lateral cephalograms and dental casts were subjected to statistical analysis. The mean distal movement of the first molar was 2.78 mm, which was highly significant (o < 0.001). It moved distally at the rate of 0.86 mm/month. There was clinically some distal tipping (3.50 degrees) and distopalatal rotation (2.40 degrees). These changes were statistically significant (p < 0.001). The second molars accompanied the first molars and moved distally by nearly the same amount. There was 1.00 mm increase in the overjet and 2.60 degrees mesial tip of second premolar. The changes in the facial skeleton and dentition bases were minimal and statistically not significant. However, there was clockwise rotation of the mandible of 1.30 degrees that was statistically significant. This was the result of molar extrusion (1.60 mm).

Cephalometric Analysis of Changes Produced by a Modified Herbst Appliance in the Treatment of Class II Division 1 Malocclusion

This study investigated treatment changes produced by the Herbst appliance in a sample of severe Class II division 1 cases, over a period of 8 months. The sample consisted of 16 girls, of whom eight were treated by the Herbst appliance, whilst eight served as controls. All cases were matched with respect to age, sex, skeletofacial morphology, and length of treatment/observation period. Twenty-two skeletal and 19 dental parameters were recorded on pre- and post-treatment cephalograms. The net treatment effect of Herbst therapy was evaluated, taking into account the growth that occurred in the control sample. The study revealed that during 8 months of Herbst therapy there was a significant increase in mandibular length, along with sagittal repositioning. The skeletal changes in the mandible were mainly responsible for overjet and molar relation correction. A slight, favourable forward rotation of the mandible was identified. Dentoalveolar features included flaring of lower incisors and distalization of upper molars. The appliance did not have any retrusive effect on the maxilla. The modified splint design differed from the original and was cemented rather than bonded.

Physical properties of root cementum: part 2. Effect of different storage methods.

This study examined the effect of 5 disinfection and storage protocols over different time periods on the hardness and elastic modulus of human premolar cementum. The sample consisted of 20 first premolars, which were divided into 5 groups of 4 teeth and stored in 1 of the following ways: (1) Miltons solution (1% sodium hypochlorite) for 10 minutes, (2) Miltons solution for 24 hours, (3) 70% alcohol, (4) desiccation, or (5) Milli Q (deionized water, Millipore, Bedford, Mass). Teeth in groups 1 and 2 were initially stored in Milli Q, tested within 6 hours, placed in their respective media, and retested. Groups 3, 4, and 5 were tested within 6 hours, then at 1 month, 2 months, and 3 months after extraction. Group 5 was further studied at 9 months, and 2 teeth in Group 4 were tested at 4 months. The hardness and elastic modulus of cementum was tested with the Ultra-Micro Indentation System (UMIS-2000, Commonwealth Scientific Industrial Research Organization, Australia) on unprepared specimens mounted on a 3-dimensional jig assembly. The results showed that storage in Miltons solution for 10 minutes had no significant effect on the hardness or elastic modulus, whereas storage for 24 hours caused a significant decrease in the hardness of cementum (P =.03). Storage in 70% alcohol for up to 4 months and in Milli Q for up to 9 months had no significant effects. Desiccation caused a significant increase in both the hardness and the elastic modulus from baseline to 3 months (P =.02 and P =.04, respectively), with most changes occurring within the first month. It was concluded that Miltons solution for 10 minutes could be considered an appropriate method for disinfection and removal of periodontal ligament fragments; however, its use for 24 hours should be avoided. Seventy percent alcohol and Milli Q are better storage methods, and desiccation should be avoided.

Muscle response to the Twin-block appliance: An electromyographic study of the masseter and anterior temporal muscles

An electromyographic study was performed on 10 young growing girls in the age group of 9 to 12 years with Class II Division 1 malocclusion and retruded mandible, who were under treatment with Twin-block appliances. Bilateral EMG activity of elevator muscles of the mandible (ie, anterior temporalis and masseter) was monitored longitudinally with bipolar surface electrodes to determine changes in postural, swallowing, and maximal voluntary clenching activity during an observation period of 6 months. The changes were noted at the start of treatment (0 month), within 1 month of Twin-block insertion, at the end of 3 months, and at the end of 6 months. The results revealed a significant increase in postural and maximal clenching EMG activity in masseter (P <.01) and a numeric increase in anterior temporalis activity during the 6 month period of treatment. The increased electromyographic activity can be attributed to an enhanced stretch (myotatic) reflex of the elevator muscles, contributing to isometric contractions. The main force for Twin-block treatment appears to be provided through increased active tension in the stretched muscles (motor unit stimulation) and from initiation of myotatic reflex activity and not through passive tension (viscoelastic properties) of jaw muscles. The results of this study reaffirm the importance of full-time wear for functional appliances to exert their maximum therapeutic effect by way of neuromuscular adaptation.

Craniofacial pattern of parents of children having cleft lip and/or cleft palate anomaly

The craniofacial patterns of 38 sets of parents who had children with cleft lip and/or cleft palate anomalies (experimental group) were compared with the 24 sets of parents of healthy (noncleft) children (control group). Using a computerized program, 248 cephalograms (124 lateral and 124 frontal) were digitized and analyzed. The parents in the experimental group exhibited a distinct craniofacial morphology, including a significant decrease in upper anterior facial height (N-Ans) and total anterior face height (V-Gn). Anterior nasal spine (Ans) and maxillary alveolar process (A) were positioned more anteriorly and superiorly in the experimental group, which contributed to a significant increase in the length of the palate (Ans-Pns) and an anterosuperior rotation of the palatal plane. The cranial base angle in the experimental group was significantly obtuse and the articular angle was smaller than that of the controls. The counterclockwise rotation of the mandible was mitigated by a significant increase in the gonial angle. Parents in the experimental group also tended to have faces which were smaller in both transverse and vertical dimensions.

Stress distribution in the temporomandibular joint after mandibular protraction: a 3-dimensional finite element method study. Part 1.

INTRODUCTION This study was designed to evaluate patterns of stress generation in the temporomandibular joint after mandibular protraction, by using a 3-dimensional finite element method. The results of the initial investigation are reported here in Part 1. The effects of varying the construction bite are reported in Part 2. METHODS A 3-dimensional computer-aided design model was developed from the magnetic resonance images of a growing boy (age, 12 years), by using I-DEAS NX (version 11.0, Siemens PLM Software, Plano, Tex). The model simulated mandibular protraction, with 5 mm of sagittal advancement and 4 mm of vertical opening. Stress distributions on the condylar neck, the glenoid fossa, and the articular disc in the anteroposterior and mediolateral directions were assessed. RESULTS Tensile stresses were located on the posterosuperior aspects and compressive stresses on the anterior and anterosuperior aspects of the condylar head. Tensile stresses were found in the posterior region of the glenoid fossa near the attachment of the posterior connective tissues. CONCLUSIONS These results suggest that, on mandibular protraction, the mandibular condyle experiences tensile stresses in the posterosuperior aspect that might help explain condylar growth in this direction. Similarly, on the glenoid fossa, tensile stresses are created in the region of posterior connective tissues; this might be correlated with the increased cellular activity in this region. Further study with variable vertical heights of the construction bites is needed.

Temporomandibular joint adaptations following two‐phase therapy: an MRI study

AIM To document the alterations within the condyle-glenoid fossa (C-GF) complex and the positional changes of the glenoid fossa in the cranium after removable functional appliance therapy and after the completion of fixed appliance therapy. SETTING AND SAMPLE The Department of Orthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India. The study sample consisted of 12 growing children (eight girls and four boys) between 10 and 14 years of age with skeletal Class II division 1 malocclusion selected on well defined criteria. MATERIALS AND METHODS All patients were treated with either the Twin Block or the Bionator appliance followed by fixed appliances. Mean total treatment duration was 28 months. The changes in and around the C-GF complex were evaluated using MRI at pre-treatment stage, after functional appliance therapy and at the completion of fixed mechanotherapy. RESULTS Forward condylar position within the glenoid fossa and articular disc retrusion with respect to the condylar head were statistically significant after functional appliance therapy. However, the condyles had a relatively concentric position within the glenoid fossa, while the articular disc resumed its pre-treatment position at the end of the treatment. Linear measurements from the centre of the external auditory meatus to the post-glenoid spine revealed a 1.3-mm forward relocation of the post-glenoid spine along the Frankfurt Horizontal plane. CONCLUSIONS Forward relocation of the C-GF complex seems to be one of the mechanisms of action of functional appliances, while the internal anatomic arrangement within the temporomandibular joint (TMJ) complex normalizes to its pre-treatment position.

Surface deterioration and elemental composition of retrieved orthodontic miniscrews

INTRODUCTION This study provides insight into surface and elemental analyses of orthodontic retrieved miniscrew implants (MSIs). The sole purpose was to investigate the behavior of MSIs while they are in contact with bone and soft tissues, fluids, and food in the oral cavity. The information thus gathered may help to understand the underlying process of success or failure of MSIs and can be helpful in improving their material composition and design. METHODS The study was carried out on 28 titanium-alloy MSIs (all from the same manufacturer) split into 3 groups: 18 MSIs were retrieved after successful orthodontic treatment, 5 were failed MSIs, and 5 were as-received MSIs serving as the controls. All MSIs were subjected to energy dispersive x-ray microanalysis to investigate the changes in surface elemental composition and to scanning electron microscopy to analyze their surface topography. Data thus obtained were subjected to suitable statistical analyses. RESULTS Scanning electron microscope analysis showed surface manufacturing imperfections of the as-received MSIs in the form of stripes. Their elemental composition was confirmed to the specifications of the American Society for Testing of Materials for surgical implants. Retrieved MSIs exhibited generalized surface dullness; variable corrosion; craters in the head, neck, body, and tip regions; and blunting on tips and threads. Energy dispersive x-ray analyses showed deposition of additional elements: calcium had greater significance in its proportion in the body region by 0.056 weight percent; iron was seen in greater proportion in the failed retrieved MSIs compared with the successful miniscrews; cerium was seen in greater proportions in the head region by 0.128 weight percent and in the neck region by 0.147 weight percent than in the body and tip regions of retrieved MSIs. CONCLUSIONS Retrieved MSIs showed considerable surface and structural alterations such as dullness, corrosion, and blunting of threads and tips. Their surfaces showed interactions and adsorption of several elements, such as calcium, at the body region. A high content of iron was found on the failed MSIs, and cerium was seen in the head and neck regions of retrieved MSIs.

Role of programmed cell death in dental anomalies associated with cleft lip and palate

A role of programmed cell death (PCD) is proposed in the production of tooth anomalies occurring in association with cleft lip and palate (Cl + P). Dental anomalies are viewed as a microform of cleft lip and palate, produced by different modulations of the same operating mechanism.

Synergistic Effect of BDNF and FGF2 in Efficient Generation of Functional Dopaminergic Neurons from human Mesenchymal Stem Cells

To understand the process of neurogenesis, generation of functional dopaminergic (DAergic) neurons from human mesenchymal stem cells (hMSCs) is important. BDNF has been reported to be responsible for inducing neuronal maturation and functionality. Previously, we have reported the efficient generation of neurons from human bone marrow derived MSCs using FGF2 alone. We hypothesize that hMSCs from various tissues [(bone marrow (BM), adipose tissue (AD) and dental pulp (DP)], if treated with BDNF on 9th day of induction, alongwith FGF2 will generate functional DAergic neurons. Hence, cells were characterized at morphometric, transcription and translational levels for various markers like MAP2, TH, NGN2, PITX3, DAT, synaptophysin, Kv4.2 and SCN5A. Functionality of in vitro generated neurons was studied by calcium ion imaging. Result analysis depicted that BDNF has effect on expression of dopaminergic neuronal markers at gene and protein levels and functionality of neurons. Among these hMSCs, DP-MSC showed significantly better neuronal characteristics in terms of morphology, expression of neuronal markers and foremost, functionality of neurons. From the present study, therefore, we concluded that i) BDNF has additive effect on neuronal characteristics and functionality ii) DP-MSC are better MSC candidate to study DAergic neurogenesis and perform future studies.