Is motor-driven insertion of orthodontic miniscrews more advantageous than manual insertion? A micro-CT evaluation of bone miniscrew contact surface area and cortical microcracks in rabbits

AIM

This in vitro study aimed to evaluate and compare the bone-miniscrew contact surface area (BMC) and the cortical bone microcracks (CM) resulting from manual (hand-driven) and automated (motor-driven) orthodontic miniscrew (OM) insertion methods.

METHODS

Thirty-three OM were inserted in the femurs of nine New Zealand rabbits using manual (n = 16) and automated (n = 17) insertions. After euthanizing the rabbits, bone blocks, each including one OM, were sawed. Micro-CT scanning was performed, and data analysis included reconstruction, binarization and quantification of morphometric parameters of BMC and the number and length of CM. Means and standard deviations for complete BMC, complete BMC proportion, cortical BMC, cortical BMC proportion, and length and number of CM were calculated. Mixed model analysis was used to adjust for more than one sample/CM per animal. A paired t-test was used to compare the number of CM between the two groups.

RESULTS

Compared to the automated insertion, manually inserted miniscrews had significantly lower complete BMC (7.54 ± 1.80 mm2 vs. 11.99 ± 3.64 mm2), cortical BMC (5.91 ± 1.48 mm2 vs. 8.48 ± 1.90 mm2) and cortical BMC proportion (79.44 ± 5.84% vs. 87.94 ± 3.66%). However, it was not statistically significant in complete BMC proportion (p = .052). The automated insertion also resulted in a significantly lower mean number of CM than the manual method (p = .012). However, the length of the cracks was shorter in the manual group but with no significant difference (p = 0.256).

CONCLUSION

Motor-driven OM insertion results in superior BMC and reduction in the number of CM, which may lead to better miniscrew stability.

Canine retraction and anchorage loss using self-ligating and conventional brackets with sliding mechanics: A split-mouth clinical study

OBJECTIVE

Appliance biocompatibility, orthodontic treatment efficiency and patient convenience are the major issues confronting contemporary orthodontic practice. Very few studies have been published till date regarding the efficiency of self-ligating brackets as against conventional brackets. Hence, the present study was planned to compare the rate of canine retraction between self-ligating and conventional brackets and to determine the amount of anchorage loss during canine retraction.

METHODS

The present clinical study was designed as a prospective, observational study comprising of 25 patients requiring first premolar extraction as a part of orthodontic treatment. Self-ligating and conventional brackets were bonded using a split-mouth study design randomly. Retraction of canines was done with 150 grams of force using Dontrix gauge with E-chains. The study was conducted in relation to upper arch only, while the rate of retraction was evaluated every 4 weeks for 3 months. Average rates of retraction in 3 months were calculated. For anchorage loss, an acrylic guide plug was used in mid-treatment cast (T0) and after 3 months of retraction (T3). The statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA). Independent t-test was used to compare the means of the two variables studied, while Pearson's correlation coefficient was used to evaluate the correlation between the variables studied in the groups included. P < .05 was considered statistically significant.

RESULTS

The correlation coefficient between the average rate of canine retraction with self-ligating brackets vs. conventional brackets over a period of 3 months came out to be 0.6434, while on comparing the data in terms of anchorage loss over a period of 3 months, the respective correlation coefficient value was found to be 0.6659 with the results being statistically highly significant in either case (P < .001).

CONCLUSIONS

Self-ligating brackets showed double the amount of displacement compared to conventional brackets in some of the cases. Also, chair side time was significantly reduced with self-ligating brackets as against conventional brackets.

Interdisciplinary treatment of a patient with amelogenesis imperfecta: Case report with a 35-year follow-up

OBJECTIVE

This case will illustrate the interdisciplinary management of an adolescent female patient with amelogenesis imperfecta (AI). It will contrast this approach and compare it to the previous "multidisciplinary" treatment rendered before the patient was referred for a second opinion.

CLINICAL CONSIDERATIONS

The patient had a family history of AI affecting all of her permanent teeth. There were many impacted teeth. The majority of her family and relatives afflicted by this opted for dentures. The patient had undergone 2 years of treatment and was told that her "braces would be removed next week." Her new dentist was concerned because the case was not ready to restore.

CONCLUSION

He recommended referral to another orthodontist for a second opinion and formulation of an interdisciplinary treatment plan that would include a periodontist, endodontist, and restorative dentist. The patient's family accepted the second opinion referral and restarted treatment with an interdisciplinary team. The restorative dentist was the quarterback for this integrated and sequenced approach. The case was ultimately restored. A 35 year follow-up shows stability with a caries free, periodontally healthy, esthetic result.

Miniscrew biomechanics: Guidelines for the use of rigid indirect anchorage mechanics

Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Although there are different ways to set up the mechanics, rigid indirect anchorage offers the greatest biomechanical versatility but is more difficult to install than conventional, nonrigid indirect anchorage or direct anchorage. The purpose of this article was to introduce readers to the concept of rigid indirect anchorage and provide guidelines as to its use.

Self-perception of the facial profile: an aid in treatment planning for orthognathic surgery

PURPOSE

To investigate the difference between the self-perception of the facial profile and analogous measurements of profile photographs in 2 age groups, adolescents and young adults, and adults.

PATIENTS AND METHODS

A prototypical Caucasian profile was constructed for each gender by averaging the profiles of 28 subjects with normal occlusion. Each prototypical profile was manipulated by protruding and retruding the lips in 1-mm increments to construct a series of 13 silhouettes. Next, 85 laypeople were divided into 2 groups: adolescents and young adults (age, 15 to 25 years) and adults (age, 26 to 55 years). They were asked to complete a questionnaire that included choosing the facial profile in the constructed series they thought most resembled their own profile photograph. For each group, the difference between the chosen and actual profile was compared using a 1-sample t test. The differences between the 2 groups in identifying their own profile were compared using a 2-sample t test.

RESULTS

The 2 groups were different in their ability to recognize their own profile (P = .040 for the upper lip and P = .006 for the lower lip). The adolescent and young adult group was most accurate, showing no significant difference from 0 for the chosen and actual profiles. However, the adult group was significantly different for both the upper (P = .040) and lower (P = .003) lips.

CONCLUSIONS

From our study results, most laypeople aged 15 to 25 years could accurately evaluate the fullness of their own facial profile, although adults aged 26 to 55 years had more difficulty in this evaluation and tended to overestimate the protrusion of their lips.

Orthodontic extrusion of the lower third molar with an orthodontic mini implant

Neurologic changes owing to damage to the inferior alveolar nerve (IAN) are the most serious complication of lower third molar (M3) extraction because of their close spatial relationship. We adopted the concept of regional orthodontic treatment and extrusion, using skeletal anchorage with an orthodontic mini implant. Two malformed M3s that were closely apposed to the IAN were extruded with the aid of 3 or 4 orthodontic brackets and a mini implant. Both of the M3s were extruded successfully. The patients experienced little discomfort with the orthodontic appliances and there was neither permanent neurologic damage nor fracture of the root fragments following subsequent M3 extraction. Orthodontic treatment using a miniscrew to separate the IAN and M3, or luxation of the M3 may be a good alternative treatment option for extrusion of a vertically impacted lower M3 with fragile roots.