Geometrical Effects of Two Different Space Closing Loops and Its Forces and Moments—A FEM Study

Objective

To evaluate the geometrical effects of double keyhole loop (DKHL) and T-loop and its forces and moments during en mass space closure using finite element method.

Materials and Methods

A 3-dimensional finite element model of maxillary arch was created and stimulated for first premolar extraction case with 0.022 slot Roth prescription bracket. DKHL and T-loop arch wire were created using 19×25 stainless steel and was opened 1 mm for activation using 2 different methods. The study was divided into 2 groups based on the loop design, method of activation, and degree of Gable bend. The stress distribution, tooth displacement, and moment-force ratio were calculated.

Result

The overall stress distribution was more or less uniform in all the groups. However, maximum von Mises stress was observed in the second premolar region for both the groups. There was greater torque and vertical control in the anterior segment and better anchorage control in posterior segment with increase in degree of Gable bend for both the loops activated using ligature tie. Moment-force ratio of 8-10 was achieved for both the loops.

Conclusion

Therefore, DKHL was as efficient as T-loop in producing the desirable biomechanical properties during en mass space closure.

Gingival tissue proliferation into the tooth following iatrogenic miniscrew insertion: A newer underreported complication

Miniscrew implant (MSI) has been reported to be an excellent, supportive orthodontic anchorage tool. The placement of MSI is not free from complication and foremost of which is penetration of MSI into the vital tooth structures. This case report is probably the first to report a newer underreported complication. Interestingly, a small bit of gingival tissue was found deep inside the dentin of the tooth, surviving and proliferating in the MSI-damaged zone. This case report is probably the first to give direct histological evidence in humans that a MSI can cause implantation phenomenon which has the potential to give rise to numerous pathologies including pulpal, periodontal, and cystic transformation. Through this report, it is emphasized that clinicians should have a structured, formal MSI placement training to avoid such instances and also underlines the need to develop protocols to be followed in the instance of an inadvertent MSI penetration.

Treatment of a unilateral complete lingual crossbite in an adult with skeletal anchorage assisted orthodontics

An asymmetry caused by a complete lingual crossbite can compromise aesthetics and impair occlusal function. The following case report describes the correction of a complete lingual crossbite using orthodontic mini implants and mini-plates to achieve absolute anchorage. A comprehensive correction of the crossbite and re-establishment of the buccal occlusion was achieved.

Corticotomy-assisted retraction: an outcome assessment

BACKGROUND

To assess the efficiency and treatment outcome of patients treated with corticotomy-assisted en-masse orthodontic retraction as compared with the en-masse retraction without corticotomy.

MATERIALS AND METHODS

Forty adult patients with bimaxillary protrusion requiring correction of bidental proclination constituted the sample. The study group consisted of 22 patients (male 11, female 11) willing to undergo surgery to reduce the duration of their orthodontic treatment and 18 patients (male 9, female 9) desirous of undergoing conventional orthodontic treatment without surgical intervention constituted the control group. Comparison of rate of retraction and anchor loss between the study and the control group was assessed.

RESULTS

Average rate of space closure of 1.8 mm/month in the maxilla and 1.57 mm/month in the mandible was observed in the study group compared to 1.02 mm/month in the maxilla and 0.87 mm/month in the mandible in the control group. The rate of retraction accelerated during the first 2 months of retraction. Molar anchor loss of approximately 0.6 mm occurred in the study group, and 1.8 mm occurred in the control group during the 4 months.

CONCLUSION

The rate of retraction with study group was twice as faster when compared to the control group, accelerating during the first 2 months of retraction. There was better anchorage control with the undecorticated molar segment during the retraction period but was found to increase as time advanced.

Miniscrew implant fracture and effects of such retained tip on dentin-pulp complex: a histological report

Miniscrew implants provide an excellent orthodontic anchorage. Besides the clinical benefits, miniscrew implants cause minor discomforts and in certain instances poses problematic complications. Damage to the adjacent tooth structure is the most feared complication of miniscrew implant placement, while fracture of miniscrew implants is the rarest. Miniscrew fracture could occur either during its placement or during its removal. An unusual case report is presented of a miniscrew implant tip fracture following root contact while attempting to remove it. This report highlights the effect of such miniscrew implant fracture on the dentin-pulp complex. The present case is probably the first to give direct histological evidence in humans that a miniscrew fracture or a retained miniscrew implant tip along the dentin/cementum without obvious miniscrew implant penetration could elicit pulp changes. Therefore this case report emphasizes the fact that prior to placing miniscrew implant, clinicians should have acquired proper training and adequate skills in terms of MSI placement and management of fractured MSI.

Orthodontic and orthognathic management of a complex mandibular asymmetry

The application of a combined surgical-orthodontic procedure for the treatment of major facial deformities (eg, asymmetries) and associated malocclusions has become an increasingly prevalent treatment modality over the past few decades. Development of sound conjoint treatment principles made possible the correction of skeletal and dental dysplasias that were unyielding to either surgical or orthodontic treatment alone. The presence and severity of dentofacial asymmetries has been the subject of many commentaries and investigations. Treatment of facial asymmetry has always been a challenge with respect to the cause and the rationale behind the corrective procedures adopted. This case report describes a 23-year-old male patient whose chief complaint was attributed solely to the clinically discernible facial asymmetry. A combined orthodontic and surgical approach was done to correct both the dental and skeletal asymmetry. The reasons for selecting this treatment protocol and the 5-year postretention stability of the final results obtained are highlighted in this report.

Comparison of shear bond strength of hydrophilic bonding materials: an in vitro study

AIM

The aim of this study was to evaluate and compare the shear bond strength of hydrophilic materials like Transbond MIP with Assure-fluoride releasing light cure sealant paste system (Reliance orthodontic product), Enhance Lc-adhesion booster (Reliance Orthodontics) Prime and Bond NT-one step adhesive with nanotechnology (Dentsply Product India) with Transbond XT as the control group.

MATERIALS AND METHODS

The study was conducted on 180 extracted human premolar teeth which were divided into five main groups. Each group contained 36 teeth, which were further subdivided into three subgroups containing 12 teeth. The teeth were bonded in three different surface environments namely dry, contaminated with artificial saliva and reprimed after contamination with artificial salvia. The brackets were bonded and cured. The shear bond strength was tested using Instron universal testing machine (4501).

RESULTS

The results were subjected to statistical analysis like 3 factorial ANOVA and compared to post-hoc using the Student Newman levels test. The residual resin on the tooth surface after debonding was evaluated with adhesive remnant index.

CLINICAL SIGNIFICANCE

The results revealed that in situations in which moisture contamination is critical there is distinct advantage in using hydrophilic primers.

Inferior alveolar nerve canal position among South Indians: A cone beam computed tomographic pilot study

Purpose:

To document a clinically relevant position of the inferior alveolar nerve (IAN) in complete dentate south Indian patients in the age group of 20–29 years using cone beam computerized tomograms.

Materials and Methods:

The investigators used a cross-sectional study design and a study sample of subjects who had a radiographically identifiable IAN canal with complete set of 28 permanent teeth excluding 3^rd molars. Predictor variables were age, tooth position, and side. Outcome variables were the linear distances between the buccal and lingual aspect of the IAN canal, buccal and lingual cortical thickness, IAN canal diameter, and the superior aspect of the IAN canal from the periapex of first and second mandibular molar. Descriptive statistics and Mann–Whitney U test were performed. P value of ≤ 0.05 was taken as significant.

Results:

The study sample was composed of 10 male and 10 female patients with a mean age of 24.2 ± 3.00 years. On average, the lingual cortical thickness was 1.68 mm at 1^st molar and 1.44 at 2^nd molar level. Gender and side influenced the outcome with varying statistical significance.

Conclusions:

The range of linear dimension of mandibular canal, cortical bone thickness, and distance between tooth apex and IAN canal have been presented for the South Indian population in the age group of 20–29 years. The implications of the findings will influence on the course of surgery. Further large-scale studies are needed to validate the findings of this study.

Chlorhexidine varnishes effectively inhibit Porphyromonas gingivalis and Streptococcus mutans - an in vivo study

Background:

Chlorhexidine varnish (Cervitec- Ivoclar Vivadent- Liechtenstein) is a sustained-release delivery system that can provide protection against white spots and gingivitis, which are common iatrogenic side effects of orthodontic treatment. Chlorhexidine in varnish form does not depend on patient compliance, does not stain teeth or alter taste sensation like the mouth rinse.

Materials and Methods:

A split-mouth technique was followed in the treatment of 30 patients selected by stringent selection criteria, evaluating a single application of the test varnish on two randomly allotted quadrants along with a placebo on the other two quadrants. Streptococcus mutans counts responsible for white spots and P. gingivalis count [using PCR test] responsible for gingivitis were done at the start of the study, and then 1 and 3 months later.

Results:

The chlorhexidine varnish reduced the Streptococci mutans count at the end of 1 month, and this reduction was statistically significant. At the end of 3 months, there was no difference in the S. mutans counts between the two groups. There was a statistically significant reduction in the P. gingivalis count at the end of both 1 and 3 months in comparison to the placebo group.

Conclusion:

Chlorhexidine varnishes are capable of reducing S. mutans and P. gingivalis and gingivitis, thus improving the overall oral health of the patient. The side effects of chlorhexidine mouth rinses are not seen with this varnish. An application schedule of at least once a month is recommended as the effectiveness is reduced comparatively at the end of 3 months.

Comparison of two imaging programs in predicting the soft tissue changes with mandibular advancement surgery

Establishing common objectives and expectations concerning the outcome of proposed surgical orthodontic therapy is a crucial part of the treatment planning process, which has been greatly simplified by imaging software. The purpose of this study was to investigate the reliability of two surgical imaging programs--Dolphin Imaging 10 and Vistadent OC--in simulating the actual outcome of mandibular advancement surgery by using a visual analog scale (VAS) judged by a panel of orthodontists, oral surgeons, and laypersons. The predictions were also analyzed with soft tissue cephalometric evaluation. The results of the study showed that in predicting the surgical outcome evaluated by the VAS, both programs received a mean rating of fair. One was marginally superior for the overall assessment among all three panelist groups. Region-wise, rating indicated the lower lip region to be the least accurate, and the submental region received the highest scores. The soft tissue cephalometric parameters showed minimal differences except for the lower lip parameters. Thus, Dolphin Imaging 10 and Vistadent OC are reliable in predicting mandibular advancement surgical outcomes with inaccuracies chiefly in the lower lip region.

Treatment of an adult patient with a periodontally compromised skeletal Class II malocclusion

This article describes the treatment of an adult female with periodontally induced bone loss, excessive gingival display when smiling, vertical maxillary excess, a convex profile, a traumatic deep overbite, and severe lip incompetence. The therapy included four steps: (1) periodontal flap surgery and root planing with regular follow-ups; (2) leveling and aligning of the maxillary and mandibular arch with closure of all spaces, the extraction of mandibular first premolars, and retraction of the mandibular incisors; (3) LeFort I two-segment osteotomy with removal of the second premolars and a 5-mm impaction to reduce the excessive gingival display and permit autorotation of the mandible to decrease the facial convexity. To close the extraction space, the posterior segment was set 4 mm anteriorly and the anterior segment 3 mm posteriorly; and (4) postsurgical orthodontics for finishing and detailing. The treatment lasted 36 months; improved facial esthetics significantly; and resulted in a normal occlusion, overjet, and overbite.

Constituents of the flowers of Persea gratissima

The flowers of Persea gratissima yielded an acylated flavonol 3-O-trans-p-coumaroylkaempferol (1), in addition to quercetin 3-O-rhamnoside (2) and isorhamnetin 3-O-glucoside (3).