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Biomedical subjects

Ravindra Nanda

Publications and source records attributed to Ravindra Nanda.

8 recordsLinked to original sources
PubMed2006

Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system.

INTRODUCTION: It is now possible to predictably move maxillary molars distally in nongrowing patients with the skeletal anchorage system (SAS) and to improve malocclusions without having to extract the premolars and regardless of the patient's compliance. The purposes of this study were to investigate the amount of distal movement of the maxillary first molars, the type of movement, the difference between actual and predicted amounts of distalization, and the relationship between the amount of distalization and age. METHODS: Twenty-five nongrowing patients (22 female, 3 male) successfully treated with the SAS were the subjects in this study. The amount and the type of distalization, the difference between predicted and resulting amounts of distalization, and the relationship between the patient's age and the amount of distalization were analyzed with wide-opening cephalometric radiographs. RESULTS: The average amount of distalization of the maxillary first molars was 3.78 mm at the crown level and 3.20 mm at the root level. The amount of distalization at the crown level was significantly correlated with the average value of treatment goals (3.60 mm). CONCLUSIONS: The maxillary molars were predictably distalized in accordance with the individualized treatment goals without regard to patient age and extraction of the third or second molars. The SAS is a viable noncompliance modality to move maxillary molars for distally correcting maxillary protrusions and malocclusions characterized by maxillary incisor crowding.

Adolescent↗
PubMed2004

Heterogeneity in vertical positioning of the hyoid bone in relation to genioglossal activity in men.

The aim of this study was to investigate whether there is any relationship among genioglossus (GG) baseline electromyographic (EMG) activity, upper airway resistance, and sex. We hypothesized that GG baseline EMG activity and its response to pharyngeal partial occlusion may be heterogeneous in men but homogeneous in women. Lateral head roentgenograms were obtained in the upright standing position with the head at natural posture from age-matched, healthy, 16 men and 15 women. A miniature balloon was placed in the retroglossal pharynx, and a record of GG EMG response was measured. The database was divided by sex and further categorized based on the increment of GG EMG response to inflation of the balloon. Both sexes included responsive subjects showing a greater GG EMG activity increase than the mean values and a counterpart, ie, a nonresponsive group. When the two subgroups were compared, the hyoid bone of the responsive subjects positioned more inferiorly than that of nonresponsive subjects in men (P < .05). When men and women were compared, most cephalometric measurements were significantly larger in the male responders, but no difference was shown in the nonresponders. We concluded that men with a lower hyoid bone show greater GG reflexive response to the partial oropharyngeal obstruction.

Adult↗
PubMed2004

The use of skeletal anchorage in open bite treatment: a cephalometric evaluation.

The aims of the present study were to assess the effectiveness of skeletal anchorage for intrusion of maxillary posterior teeth, to correct open bite malocclusion, and to evaluate the usage of titanium miniplates for orthodontic anchorage. Anterior open bite is one of the most difficult malocclusions to treat orthodontically. Currently, surgical impaction of the maxillary posterior segment is considered to be the most effective treatment option in adult patients. Various studies have reported the use of implants as anchorage units at different sites of midfacial bones for orthodontic tooth movement. The zygomatic buttress area could be a valuable anchorage site to achieve intrusion of maxillary posterior teeth. Ten patients, 17 to 23 years old and characterized with an anterior open bite and excessive maxillary posterior growth, were included in this preliminary study. Titanium miniplates were fixed bilaterally to the zygomatic buttress area, and a force was applied bilaterally with nine mm Ni-Ti coil springs between the vertical extension of the miniplate and the first molar buccal tube. The results showed that, with the help of skeletal anchorage, maxillary posterior teeth were intruded effectively. As compared with an osteotomy, this minimally invasive surgical procedure eased treatment and reduced treatment time and did not require headgear wear or anterior box elastics for anterior open bite correction. In conclusion, the zygomatic area was found to be a useful anchorage site for intrusion of the molars in a short period of time.

Adolescent↗
PubMed2002

Effect of varying the force direction on maxillary orthopedic protraction.

The aim of this study was to examine the effect of varying the force direction on maxillary protraction. A total of 20 patients with class III maxillary retrognathism were randomly divided into two groups. Group 1 was comprised of nine patients with a mean age of 8.58 years, and group 2 was composed of 11 patients with a mean age of 8.51 years. Both groups received a cap splint-type rapid palatal expander and the screw was activated twice a day for 10 days. After the expansion procedure the face mask protraction procedure was initiated. In group 1, we applied the force intraorally from the canine region with a forward and downward direction at a 30 degrees angle to the occlusal plane. In group 2, the force was applied extraorally 20 mm above the maxillary occlusal plane. In both groups a unilateral 500 g force was applied and the patients were instructed to wear the face mask for 16 h/d for the first three months and 12 h/d for the next three months. The Wilcoxon sign rank test was used to evaluate the effect of the two different face masks, and a Mann-Whitney U-test was carried out to evaluate the differences between the two groups. The results showed that both force systems were equally effective to protract the maxilla; however, in group I we observed that the maxilla advanced forward with a counter-clockwise rotation. In group 2 we observed an anterior translation of maxilla without rotation. The dental effects of both methods were also different. The maxillary occlusal plane did not rotate in group 1, in contrast to the clockwise rotation in group 2. The maxillary incisors were proclined slightly in group 1, but in contrast they were retroclined and extruded in group 2. In conclusion, the force application from near the center of resistance of the maxilla was an effective method to prevent the unwanted side effects, such as counter-clockwise rotation of the maxilla, in group 1. The group 2 results suggest that this method can be used effectively on patients who present as class III combined with an anterior open bite.

Biomechanical Phenomena↗
PubMed2002

Sex differences in genioglossus muscle response to changes in pharyngeal resistance.

The genioglossus (GG) muscle's response to partial oropharyngeal occlusion was studied in age-matched, healthy awake men (n = 16) and women (n = 15). A miniature balloon was placed in the retroglossal pharynx, and the GG's electromyographic (EMG) reflexive response was evaluated in different body postures. We assumed that inflating the pharyngeal balloon and changing the body posture from upright to supine would increase pharyngeal airway resistance. Our hypothesis was that the change in airway resistance would elicit a different response in the GG muscle depending on sex. Our results showed that GG activity during natural breathing was higher in women than in men. GG EMG activity did not change upon inflation of the balloon in women. In contrast, when the balloon was inflated in the men, the GG's basal activity increased (P <.01) in both the upright and the supine positions. Women appeared to show a higher GG baseline EMG activity during spontaneous breathing at rest, while men were more responsive to the partial occlusion of the pharyngeal airway.

Adult↗