Summer 2001 Presentation Summary:

Dr. Kapila is a strong advocate for using case-specific mechanics to eliminate or minimize irreversible side effects, treatment time, esthetic compromise, and instability, which result from ill-conceived treatment procedures.

Patients requiring the non-surgical management of complex malocclusion include adolescents with multiple agenesis, adults with periodontal disease, and multiple missing teeth, and all skeletal malocclusions.

Dr. Kapila suggests a tripartite agenda: wire selection, mechanics, and multidisciplinary collaboration.

Wire Selection

The orthodontist has an unprecedented array of tools at his command when it comes to the choice of wires. Proper selection can significantly affect the treatment process. Wire characteristics include stiffness, spring back, stored energy, surface friction, formability, and joinability.

A wire's ability to accept a large deflection without deformation adds more stored energy to the procedure. This translates to lower, more constant forces more accurately regulated, longer activation periods, and fewer arch-wire changes. Nickel titanium is the optimal choice for this set of characteristics, followed by beta titanium, then stainless steel. Different objectives require wires with different characteristics. For example, moment-to-force ratios reflect wire stiffness.

There are a number of ways to move a tooth. Uncontrolled tipping moves the crown in one direction, the root in the opposite direction. Controlled tipping results in crown movement while keeping the root stationary. Translation requires force applied through the center of resistance to create bodily movement. Angulation of a tooth root (torque) requires force that repositions the root more than the crown.

Wire stiffness becomes an issue depending on whether the clinician desires translation, or torque. To translate a tooth, one must provide equilibrium between the moment of force and the moment of couple. To produce a change in root angulation or torque, one provides a moment of couple that predominates over the moment of force. Stainless steel is a far more efficient material to accomplish translation and root movement compared to nickel titanium, which requires a much larger deflection to produce the necessary couple. Stainless steel wires also limit undesirable side effects, such as extrusion of anteriors and loss of Class I molar occlusion in the final stages of treatment.

Surface friction affects the force required to accomplish translation. Here, too, material selection plays a role. Friction, caused by microscopic surface irregularities, increases with the number of brackets engaged in the arch wire. It decreases the force delivered to the system, which must be increased to a corresponding degree to achieve the desired result. Stainless steel contributes the least amount of friction. Beta titanium creates the highest degree of friction, but friction in the clinic is highly dependent on the amount of force pressing the wire against the walls of the bracket slot. Ceramic brackets without metal inserts contribute even higher frictional resistance.

Mechanics

Arch-wire mechanics have as much impact on the efficiency of tooth movement as material selection. Continuous mechanics are appropriate in the initial phase treatment. They have the advantage of simplicity and less chair time. Continuous mechanics also encourage better hygiene and provide greater patient comfort. The disadvantages include round-trip movement, the tendency to squander anchorage, prolonged treatment time, and a contribution to periodontal deterioration.

Dr. Kapila noted that when managing complex cases segmented mechanics could be a good choice. Segmented mechanics are force-specific, providing force application directly as required to achieve a desired outcome. Greater accuracy in force application results in fewer side effects, better anchorage control, shorter treatment time, and diminished periodontal impact. Segmented mechanics have the disadvantage of complexity, additional chair time, increased patient discomfort, and more challenging hygiene demands.

Multidisciplinary Collaboration

Statistics tell us that only 25% of complex cases can be managed by the orthodontist alone and 45% are treated by two providers (30% ortho-restorative, 8% ortho-perio, and 7% ortho-surgery). The remaining 24% of complex cases require the services of three providers. Multidisciplinary collaboration is the third principle for successful management of complex malocclusion. The team must produce a realistic treatment plan that is acceptable to all members of the team. Dr. Kapila suggests that one person serve as the facilitator, coordinator, and advocate in order to ensure optimum treatment results.

Typically, such malocclusions are more difficult for the orthodontist to manage for several reasons: missing teeth compromise available anchorage, bone loss results in a center of resistance closer to the apex, occlusal and dental relationships are more compromised, and the absence of facial growth creates mechanical limitations.

Dr. Kapila's four Cs of interdisciplinary treatment are: Communication, Comprehensive treatment plan and objectives, Coordination, and Compliance. The coordinator must keep these in mind when communicating the objectives for procedures that cut across provider boundaries. Examples include location for implants and root positions, optimal distribution of existing teeth, improvements of crown/root ratios, and conflicting esthetic requirements. The coordinator must also ensure that the patient receives the correct procedure at the right time.

Once a tentative treatment plan is derived and sequenced, it should be presented to all providers with opportunity for their review - clarification and verification by all concerned is essential. Then, all providers must sign off on an agreed upon course. Such attention to detail and review of treatment progress are essential for successful results in cases requiring multidisciplinary treatment.

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