The 15 Keys to Success in Orthodontic treatment

1. The 15 Keys to Orthodontic Success
(Alexander, R. G.)
Shaimaa Saad Zaki,
Assistant Lecturer at Department of Orthodontics, Faculty of
Dentistry, Mansoura University

2. The 15 Keys to Orthodontic Success
(Alexander, R. G.)
 15 measurements taken from
the diagnostic records can provide a brief yet accurate determination of goals necessary
to achieve successful treatment and long-term stability for the individual patient. Include
1) Cephalometric xray
2) Study casts
3) Panoramic radiograph
4) Facial photographs

3. Cephalometrics: The tetragon-plus analysis
1. Mandibular incisor inclination
Three possibilities exist for an ideal posttreatment value for IMPA :
1. In most nonextraction treatments, the mandibular incisors should be maintained within 3
degrees of their original position (the 3-degree rule). Almost all studies indicate that
violating the 3-degree rule (inclining the incisors more than 3 degrees from their original
position)will result in a higher incidence of relapse in the long term.
 Clinically, –5-degree torque in the mandibular incisor bracket will help to control this
critical position.

4. 2. In patients with a deep bite, especially a division 2 deep bite, the mandibular incisors are
often inclined lingually and should be advanced, sometimes significantly.
3. In patients with bimaxillary protrusion, the incisors are often significantly flared.
In these patients, the incisors should be retracted more than 3 degrees.

5. 2. Mandibular plane angle
 The goal is to maintain the mandibular plane angle.
In very low-angle cases, the mandibular plane may have to be increased during treatment.
 In patients with average vertical dimensions and good growth potential, orthopedic
forces, if managed properly, can be very successful without significantly increasing the
vertical plane.
The problem arises when the patient presents with a high-angle vertical pattern. In such
cases, maxillary molar control is critical to prevent molar extrusion. For example, if headgear
is misused and only a cervical neck strap is prescribed for high-angle patients, the maxillary
molars may be extruded, causing vertical openings.

6. 3. Maxillary incisor inclination
• In normal skeletal patterns, the maxillary incisor should be inclined 101 to 105 degrees relative to
SN .
• Controlling the inclination (torque) of the maxillary incisor is critical to the creation of adequate
incisal guidance.
With the Alexander bracket prescriptions, incisor inclination (torque control) can be accomplished
with a 0.017 × 0.025-inch stainless steel archwire in the pretorqued 0.018-inch slot anterior brackets.
4. Interincisal angle
• The accepted angle between the maxillary and mandibular incisors (U1-L1) is from 130 to 134
degrees.
• Although orthodontists have limited options for positioning of the mandibular incisors, the maxilla
allows more freedom in the positioning of the maxillary incisors. However, the final position of the
maxillary incisors is directly related to the position of the mandibular incisors.

7. 5. Tetragon plus
Additional information garnered from the cephalogram is referred to as tetragon“plus.” These data
include the measurements to determine sagittal skeletal dimensions and the cephalometric soft
tissue profile.
5a. Sagittal skeletal dimensions
Ideally, treatment of a skeletal Class I, II, or III malocclusion will result in a sagittal jaw
relationship (sellanasion–point B) of 1 to 3 degrees
5b. Cephalometric soft tissue profile
Ideally, Holdaway’s harmony line, connecting the soft tissue pogonion with the upper lip, should
touch the lower lip and bisect the nose . However, many variations of this esthetic measurement
can exist, depending on the size of the chin and nose.

8. Study casts
6. Mandibular intercanine width
The treatment goal for this critical measurement is to maintain the original intercanine width .
*Longterm studies have shown that any expansion of more than 1 mm will invariably relapse
*A common belief is that, with extraction treatment, the mandibular canines can be retracted to a
wider part of the arch;
therefore, canine expansion is acceptable. If this were true, the long-term studies of extraction
treatment would show the stability of canine expansion. The literature does not support this.
*The only exception to this rule might be when the canines have erupted lingually,inside the
normal arch. In these cases, the canines can be expanded into that normal arch form

9. 7. Maxillary intermolar width
When measured from the lingual groove at the cervical line of the maxillary first molars, the maxillary
intermolar distance should be between 34 and 38 mm . While expansion of the mandibular
intercanine dimension should be avoided, the maxillary molars can be expanded.
8. Arch form
*An ovoid arch form design will provide the most esthetic and stable form for most patients .
*This conclusion is based on the following rationale: If the
mandibular canine area is not expanded and the positions of the mandibular incisors are controlled,
the maxillary and mandibular anterior arch forms will be mostly predetermined. If the maxillary
intermolar width is made to be approximately 36 mm, the maxillary and mandibular posterior widths
and arch forms are then determined. Thus, a line formed between the canines and the molars
results in an ovoid arch form.
.

10. 9. Leveled mandibular arch
*Leveling the curve of Spee in the mandibular arch is critical to the correction of deep bites and
the maintenance of overbite correction,
*the better the leveling, the better is the stability
10. Occlusion
*Everyone agrees that good occlusion is critical for function, health, and stability.
*Excellent occlusion consists of a good Class I canine relationship, normal intercuspation of
posterior teeth, normal overbite and overjet relationships, canine protection in lateral
movements, anterior guidance, and a centric relation that
coincides with maximum intercuspation

11. Panoramic radiograph
11. Root positioning
*the roots of the anterior teeth, canine to canine, should be divergent in both the maxilla and the
mandible .
*The angulations to accomplish this root positioning are integrated into the bracket prescriptions.
12. Periodontal health
observation of the interproximal bone; root apices; and unusual conditions such as impactions,
abscesses, and root resorption
13. Temporomandibular joint
Depending on other factors, initial diagnosis of the temporomandibular joint conditions can be
made by observing the size and shape of the condyles on a panoramic radiograph of good quality
. If joint symptoms are present, a more thorough investigation is required.

12. Facial photographs
14. Soft tissue profile
*The final position of the lips is dependent on the position of the maxillary and mandibular anterior
teeth that create the interincisal angle
*If these teeth are positioned too far labial or lingual, an unfavorable facial profile can result.
15. Smile
The Alexander Discipline is intended to produce the following results at the end of orthodontic
treatment :
• Coincident dental midlines
• Coincident facial midlines
• Absence of dark buccal corridors
• Esthetically positioned teeth
• A balanced smile line
• A balanced smile arc

13. Reference