Please activate JavaScript!
Please install Adobe Flash Player, click here for download

Ortho Tribune Middle East & Africa No.6, 2017

Dental Tribune Middle East & Africa Edition | 6/2017 ORTHO TRIBUNE E3 ◊Page E2 placement of the cortical bone.23 This pathologic process is well established and has been extensively document- ed in case reports and textbooks. The interstitial pressure of various odon- togenic cysts have been measured24 and found to exert an ultra-low force load on the alveolar bone. This phenomenon clearly demonstrates that the developed alveolus can be modeled via pathologic induction with light, continuous force. Another commonly observed example of bone modeling is the bulge of the cortical plate associated with a pala- tally impacted canine. The impacted tooth is typically associated with an enlarged follicle. When the canine is exposed and brought into the center of the alveolus, a normal palatal con- tour returns. Kokich and Kokich25 demonstrated localized modeling of the adult al- veolus in response to tooth displace- ment. Light, continuous orthodontic force was employed to distalize a tooth into the atrophic alveolar ridge associated with a congenitally ab- sent second premolar. The distalized tooth moved with its supporting bone, changing the size and shape of the atrophic alveolus (Fig. 3). Fontenelle reported alveolar bone modeling with a passive/active dis- sociation appliance in non-growing patients.26 The appliance (Fig. 4) con- sisted of a passive, rigid-cast lingual arch and active, low-modulus wires activated between the cast lingual arches. Dissociation of the passive and active components facilitates the application of low, constantforce load with near-constant moment-to- force ratios, resulting in bone mod- eling induced by dental displace- ment. Clinical cases were shown demonstrating lateral modeling of the alveolus as observed by Frankel and localized alveolar modeling with tooth displacement as observed by Kokich and Kokich. Williams and Murphy described al- veolar bone modeling with evidence of apposition of bone on the maxil- lary buccal alveolus in permanent dentition patients (Fig. 5a-c).27 This was induced by a light, continuous load applied bilaterally to the max- illary alveolus with the Max 2000® alveolar development appliance (Fig. 5a).* Their appliance consists of two nickel-titanium springs embedded in and connecting separate acrylic panels in a framework retained by bands on the first bicuspids and first molars. The transpalatal springs delivered 150 grams of force each in a lateral direction. Biopsies were performed on two patients upon completion of lateral alveolar devel- opment. The specimens were har- vested via full-thickness flaps from the labial alveolar crest between the maxillary right first bicuspid and canine (Fig. 5b). An internal control specimen was taken from intersep- tal bone between the ipsilateral man- dibular first bicuspid and canine (Fig 5c). Standard hematoxylin and eo- sin stained sections were examined with and without polarized light and a maxillary specimen was subjected to fractional analysis. The maxillary treatment sections demonstrated the absence of the lamellar pattern characteristic of mature bone and polarized light demonstrated a woven bone pattern characteristic of immature or new bone (Fig. 6). In addition, fractional analysis of the polarized light speci- men demonstrated fractal patterns suggestive of woven bone modeling. Alveolar Bone Modeling with a Fixed, Continuous-Arch Appliance In recent years, fixed, passive self- ligating (PSL) appliances have been developed along with low-friction/ low-force, continuous-arch protocols for orthodontic treatment. Dr. Hish- am Badawi has reported evidence28 with his OSIM apparatus29 support- ing the ability of passive self-ligating brackets to deliver lower-magnitude forces compared with elastomeric-li- gated appliances applied to the same malocclusion in an in vitro model (Fig. 7). Evidence has also been re- ported supporting the ability of pas- sive self-ligating brackets to achieve a reduction in the frictional resistance to sliding at the bracket/wire inter- face.30,31,32 The resultant load applied to the teeth and transmitted to the alveolar bone ecessarily decreases as the frictional resistance to sliding and the force required to overcome it decreases. Clinical evidence has been reported demonstrating significant widening of the dental arches follow- ing treatment with the low-friction/ low-force Damon System.33,34,35 An increase in the transverse dimen- sion of the alveolar bone has also been reported in response to the low, biomechanical load delivered by this treatment regimen.36,37 The following case reports provide examples of the alveolar bone mod- eling the authors have observed over a combined 28 years of experience utilizing the Damon passive self- ligating fixed appliance and treat- ment protocols advocated by Dr. Dwight Damon. Discussion The case reports presented dem- onstrate examples of the change ÿPage E4 CASE STUDY 1 CHILD ALVEOLAR MODELING: Pretreatment Diagnosis A 9-year-old male patient presented in the mixed dentition with prema- ture loss of his maxillary left primary canine with space loss and a blocked- out, unerupted permanent canine. His mandibular arch presented with severe crowding and completely blocked-out and unerupted lateral incisors. He exhibited normal cir- cumoral muscle tonus and lip com- petence. The lateral ceph showed upright maxillary and mandibular incisors. I mixed-dentition Treatment Summary Phase treat- ment was initiated with Damon passive self-ligating appliances, in- cluding brackets placed on all the non-mobile primary teeth. Copper Ni-Ti wires (.014”) and light NiTi coil springs were activated one-half-of- a-bracket length between the man- dibular permanent central incisors and primary canines, and between the maxillary left permanent lat- eral incisor and primary first molar. Low-torque brackets were selected for the upper and lower incisors to help minimize proclination from the force of the spring. Damon wire sequence protocols were observed. Result Pre- and posttreatment images dem- onstrate the treatment result after 16 months of treatment. The size-cor- rected view of the mandibular arch illustrates the significant change in the size and shape of the mandibular alveolar bone induced by this ap- proach. Similar changes were seen in the maxilla as well. The patient’s parents were pleased with the result of Phase I treatment and opted not to pursue Phase II finishing treatment. CHILD ALVEOLAR MODELING: Pre-/Posttreatment Comparison Demonstrates Alveolar Bone Modeling CHILD ALVEOLAR MODELING: After Eruption of Permanent Teeth. Phase II Treatment was Not Pursued in this Case PRETREATMENT POSTTREATMENT

Pages Overview