EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
In summary, the variance in tongue and lip pressures seen in “normal”<br />
individuals indicates that a wide range of maximum intraoral pressures occurs in<br />
the general population, making broad predictions about the effects of the<br />
perioral musculature difficult at best.<br />
Weinstein et al. (1963) reported that the opposing forces and pressures<br />
exerted on the dentition from, principally, the tongue, cheeks, and lips can be self<br />
negating, such that a system of equilibrium between hard and soft tissues exists.<br />
Further conclusion were: (1) forces exerted on the teeth by the surrounding soft<br />
tissue may cause tooth movement much like orthodontic appliances, (2) each<br />
tooth may have more than one position of stable equilibrium within the system<br />
composed of the oral environment, and (3) differential forces, even of small<br />
magnitude, if applied over a considerable period of time, can cause changes in<br />
tooth position.<br />
Proffit (1978) extended the work of Weinstein et al. (1963) by presenting an<br />
additional review of the subject of equilibrium. The results of Proffit’s research<br />
identified four primary factors that create equilibrium between the dentition and<br />
the surrounding tissues:<br />
1. intrinsic forces by tongue and lips,<br />
2. extrinsic forces: habits, orthodontic appliances,<br />
3. forces from dental occlusion, and<br />
4. forces from the periodontal membrane.<br />
Teeth characteristically exist in a state of equilibrium with the<br />
surrounding soft tissues. For posttreatment results to maintain stability, the<br />
resting pressures of the soft tissues will determine the final tooth positions.<br />
Riedel (1976) acknowledged the importance of considering muscle balance<br />
when positioning teeth to gain lasting stability, but contended that establishing a<br />
harmonious muscle balance is almost impossible to do until growth and<br />
development have been completed. “The orthodontist moves the teeth into the<br />
relationships which he considers correct, but Nature eventually repositions them<br />
where they can best serve the patient” (Huckaba 1952, p349).<br />
Continued Physiologic Growth and Development<br />
About 1900, retention consisted of holding teeth in position until<br />
believed stable. This philosophy of stability changed when the Huning case<br />
of Dr. Angle demonstrated that anterior teeth can change axial inclinations<br />
during and after retention. This was the beginning of the realization that<br />
18