Third molar or wisdom Teeth retention may be beneficial in many situations. Some investigators maintain that third molars or wisdom teeth or wisdom Teeth could be used at a later date as replacements or for prosthetic abutments in case of loss of first and second molars. Third molars or wisdom teeth or wisdom Teeth could also be used as transplants. In shallow mesio angular impactions Richardson used a one stage method. A second molar tube can normally be bonded onto the buccal aspect of a partly erupted lower third molar, if enough enamel is visible. It is then possible to include the tooth in full treatment, if other teeth are already bonded and bracketed. If the case is not fully banded, then lower second or first molars alone can be used with a lingual arch for support.
In deep mesio angular impactions, a two stage method is used. If it is not possible to bond onto the buccal surface, a different technique is used which can be delayed until 18 -19 years of age to allow time for the tooth to improve its position. The first stage involves bonding a second molar tube onto the occlusal surface of the lower third molar. The hook is removed from the tube, before bonding. Lower first or second molars are banded with a lingual arch, using first molar bands and brackets. A small sectional archwire with a compressed coil spring, is used to provide a distalizing and up righting force to the crown of the impacted molars. After some up righting using this method, it is normally possible to bond a tube buccally for the second stage.
Ike Siodov et al in AIO 89 describes an orthodontic up righting technique similar to 'Sling shot ' appliance described by Moyers and by Profitt. Modified impaction related surgical procedures provide easy application of techniques to facilitate exposure of unerupted and partially erupted third molars or wisdom teeth or wisdom teeth and allow orthodontic manipulation.
After surgical exposure a cleat is bonded in center of mesial marginal ridge. The wire port ion of the appliance is fabricated from 0.032 inch stainless steel wire and adapted closely to the mucosa. The mesial hook is placed 3 mm distal to the distal portion of the third molar. Standard soldering techniques are used to attach the wire to the buccal (or lingual) surface of the band. Appliance is cemented in place and is activated with elastic modules.
By manipulation of the distal arm of the appliance either buccally or lingually, depending on the desired movement, teeth can be directed or rotated with some effectiveness. Variation can also be accomplished by alteration of the bond position of the cleat. Following activation, rapid up righting and distalisation will occur in 3 to 6 months in most cases. Grinding of occlusal surface is not necessary. When the third molars or wisdom teeth or wisdom teeth are upright, the appliances are removed and the third molars or wisdom teeth or wisdom teeth are banded, leveled and aligned with the rest of the teeth.
This procedure is contraindicated when the molar to the uprighted has no antagonist or is severely malformed or is abnormally large or small, and it should he done carefully when there is a tendency for open bite.
Advantages of Uprighting Impacted Third molars or Wisdom Teeth
1. Ease of fabrication and manipulation.
2. Rapid treatment.
3. Little discomfort.
4. No demands for patient cooperation.
Orton and Jones in JCO 87 described a simple whip spring that is unobtrusive and fairly fast acting with a treatment time of 4 to 12 months. It is used for disimpacting mild to severe mesially impacted lower terminal molars (LTM). LTM crown must be accessible for an edgewise tube preferably on a band. Partial seating of the band on the mesial surface is acceptable at first, which can be fully seated as correction proceeds. If the impacted molar has not sufficiently erupted then surgically expose distobuccal surface and bond an attachment.
The whip spring is fabricated with 0.018 x 0.025 wire for 0.022 slot and 0.017 x 0.022 wire for 0.018 slot. A circular loop is placed mesial to the tube to prevent posterior displacement of the wire and to provide attachment of an elastic module that anchors the wire in the tube. Wire extends mesially from the loop. A vertical bend is pieced occlusally next to the midbuccal fissure of the anchor molar. The wire is curved lingually to pass through the midbuccal groove onto the occlusal surface. It is then contoured distally to run along the occlusal surface. Moving the whip to the occlusal surface of the anchor molar activates the appliance. The whip spring can be reactivated in the mouth by lifting the wire away from occlusal surface and gently squeezing the arm of the spring between loop and vertical bend with Tweeds loop forming plier. After initial adjustment of 3 to 4 weeks, adjustments every 6 weeks seem to be adequate. Over correction is advised.
The force of the whip tends to extrude the impacted molar and intrude the anchor molar. If there is too much intrusion of anchor molar, a new whip can be made that extends to another anchor tooth. The couple tends to disimpact the LTM by a combination of distal crown tipping and mesial root movement, resulting in root paralleling of the molars.
If the vertical development of the LTM is impeded by an upper molar, then the over erupted upper molar must be intruded by a removable appliance with an intrusive arm.
Replacement of Third molars or Wisdom Teeth for Second Molars
During growth o f maxilla, space to accommodate the erupting first, second and third molars or wisdom teeth or wisdom teeth must be created by growth in the posterior region of the tuberosity. The maxillary growth in this area must normally be downward and forward to create room for the eruption of each succeeding molar. If growth in this region is insufficient, abnormal eruption or lack of eruption will be the result. According to Malcolm R Chipman in AJO 1961 the third molars or wisdom teeth or wisdom teeth can be substituted for the second molars in certain situations and solve some of the problems of maxillary tuberosity area. The indications for eliminating maxillary second molar and replacing it with third molars or wisdom teeth or wisdom teeth are:
1. Maxillary third molars or wisdom teeth or wisdom teeth are of fair size and shape with the possibility of good root development.
2. Small, restricted maxillary tuberosities and the possibility of interference with distal movement in maxillary posterior region.
3. Second molars erupted buccally.
4. Second molars are decayed, badly decalcified or having large restorations.
5. Maxillary third molars or wisdom teeth or wisdom teeth in favourable position and angulation relative to second molars and maxillary tuberosity.
6. Maxillary third molars or wisdom teeth or wisdom teeth in favourable relation to mandibular second molars.
7. Desirability of relieving the anchorage unit s of an overload.
The replacement of maxillary second molar will be considered in both Class I and Class II malocclusions. The contraindications for substitutions are:
1. Maxillary third molars or wisdom teeth or wisdom teeth too high in the tuberosity.
2. Maxillary third molars or wisdom teeth or wisdom teeth too low in relation to the second molars.
3. Poor angulation in relation to second molar and the tuberosity.
4. The possibility of third molars or wisdom teeth or wisdom teeth involving maxillary sinus.
5. Small, odd shaped third molars or wisdom teeth or wisdom teeth or an indication of the formation of small roots.
There is a great variation in the time of development of third molars or wisdom teeth or wisdom teeth and this together with the amount of development in the tuberosity region, has a bearing on the decisions to be made in the event of a needed maxillary distal movement and a possible replacement of the second molar by third molar. For this reason the dental age as evidenced by the development of dental components, must be given as much considerations as chronological age.
The shape of third molar crowns is also considered. Small crowns with narrow width at the cervical margin not lend themselves to development of normal sized roots. Many third molars or wisdom teeth or wisdom teeth have odd shaped crowns with irregular cusp formations, and, while occlusal grinding frequently is needed, there is a limit to its use and these teeth cannot be recommended.
During its eruption following a second molar extraction, the third molar rotates or tip mesially as it descend. The amount of rotation is directly associated with the degree of angulation. The greater the degree of angulation, the greater is the amount of rotation, with the center of rotation being based on root apex. This rotation together with the downward and forward path of eruption is a major factor in determining when the second molar extraction may be planned. The ideal condition calls for the descending
third molar to come into contact with the maxillary first molar and into occlusion with the mandibular second molar at the same time.
In a Class I malocclusion, the third molar should have descended to the extent that the occlusal surface is approximately level with the vertical mid line of second molar root and the mesial surface of unerupted third molar is fairly in line horizontally with the distal
surface of mandibular second molar. Following extraction of second molar, the third molar will then descend in a downward and forward arc, rotating into contact and occlusion at the same time. If third molar is at a much higher point there is a possibility of impaction or premature cont act, before occlusion is attained. If it is at a lower level in relation to second molars, it is likely to erupt into occlusion before contact is established with first molar, resulting in open contacts and poor interproximal situations. In Class II malocclusions, the crown of maxillary third molar is horizontally advanced in relation to the mandibular second molar. In Class II cases in which second molar is to be extracted, the most ideal location of third molar is approximately at the junction of crown and root of second molar. The angulation of maxillary third molars or wisdom teeth or wisdom teeth to the plane of occlusion and their relation to the tuberosity must be carefully considered. The usable angulation will range from 0 to +30 degree (Distal tip) to occlusal plane.
Orton-Gibbs et al in AJO 2001 described the eruptive path of maxillary and mandibular third molars or wisdom teeth or wisdom teeth after extraction of second molars with the use of radiograph and assessed the final position from study models. They showed that the angulation o f the mandibular. Third molar crown long axis showed progressive uprighting from a mean of 55 degrees to the occlusal plane at the start of active treatment (SAT). Uprighting of mandibular third molars or wisdom teeth or wisdom teeth from SAT to end of active treatment (EAT) was limited (mean 6 Degrees). However the third molars or wisdom teeth or wisdom teeth continued to upright thereafter on average a further 13 degree. Clinically it is important to note that EAT radiographs will not give a true picture of the likely final mandibular third molar angulation. Approximately 50% of the space closure occurs by EAT. Interestingly space closure is not a result of mesial tipping but is due to significant horizontal translation. The relationship of the first and the third molar crown should be the most important indicator of successful outcome, not angulation of the whole tooth. The results confirm findings by Dacre and Richardson and Richardson that the original angulation of the third molar is not a reliable predictor of outcome for third molar position.
In contrast to the mandibular third molars or wisdom teeth or wisdom teeth, the maxillary third molars or wisdom teeth upright rapidly by 14 degrees on average, from SAT to EAT. Angular changes are minimal as the maxillary molars settle into occlusion. The rate of vertical change is rapid, with almost 7 mm of eruption occurring by the completion of active treatment and a further 6 mm after active treatment.
The third molars or wisdom teeth in the study were invariably in a position that maintains a good functional occlusion. The periodontal health of the sample was excellent. There was no correlation between third molar position and the presence of gingivitis or periodontitis. The results showed that relief of crowding by removal of second molar is a realistic option in appropriate cases with mild to moderate crowding, particularly in patients in whom third molar impaction is predicted and in reducing the likelihood of increasing crowding through the teenage years.
Auto Transplantation of Third molars or Wisdom Teeth
Auto transplantation of teeth has become an accepted and reliable treatment modality in patients with early loss of teeth or aplasia. According to William Northway in AJO 80 autogenic tooth transplantation can give the concept of space management a much broader horizon. Third molars or wisdom teeth have been frequently used for transplantation. These teeth, which are often extracted, have served well as replacements, for cariously destroyed first molars. Their root development which continues into the late teen s and twenties makes these teeth suitable for use into adulthood. The last tooth in the arch may offer better access for removal and it is essential that the root not be damaged in any way during its relocation. The prognosis for successful transplantation is diminished as the root apex nears closure. Revascularisation must take place. While post operative resorption is rarely reported, the effective reduction in root length is minimized by allowing adequate development prior to transplantation. Hale believed that the most favorable time for transplanting was at 3 to 5 mm of root formation. Apfel stressed the need for delaying transplantation until after furcation formation. Andreasen, Baum, Peskin and Guralnick have contended that the results will be maximized if the operations are performed sometime between one third and three fourth of completion of root formation.
Proper alveolar architecture is essential for housing the transplant. The recipient site should be covered with adequate attached, keratinized tissue to allow proper coverage or approximation to the transplant and it should be free of chronic inflammation. Mesiodistal space deficiencies be eliminated prior to the surgical procedure, either by orthodontic means or by slicing of adjacent teeth. Also there should be adequate Iabiolingual width on the ridge to accommodate alveolar plates on both surfaces.
Surgical Procedure for Transplantation of Third Molar or Wisdom Tooth
A full thickness muco-periosteal flap should be employed, allowing adequate exposure for atraurnatic preparation of the recipient site. A very gentle handling of the soft tissue is ensured. The socket is prepared with bone burs and rongeurs. Once the socket is judged to be of adequate depth and circumference, a trial insertion of pre sterilized dummy tooth can be made. Ideally, the preparation of the recipient site will allow insertion deep enough that the cusp tips will be at or apical to the alveolar crest height. This allows eruption and hence roots formation postoperatively. Now the transplant can be removed. Again, adequate flaps allow exposure and a minimum of trauma. With gentle manipulation of surgical instruments, the dental follicle is removed from around the crown. The tooth is removed and transferred immediately to the previously prepared crypt. It is preferable that the tooth be manipulated only by its crown. In the event that buccolingual width does not allow proper placement, it can he inserted in a rotated position. This wiII allow preservation of alveolar crest and the tooth can later be repositioned orthodontically as desired. Muco-periosteal flap is repositioned and sutures are placed over the crown to hold the tissues together and tooth in its crypt. After a week or 10 days sutures are removed and direct bonded stabilization can be employed for up to 6 weeks.
Oskar Bauss et al in AJO 2004 in their study determined the influence of orthodontic tooth movements on pulpal and periodontal conditions in transplanted immature third molars or wisdom teeth. The indication for transplantation was aplasia of premolars or early loss of molars.
In patients with horizontal atrophy of alveolar process with narrow alveolar ridges and unfavorable root morphology, transplants were placed in 45 to 90 degrees distally rotated positions. Derotation to a correct position in the dental arch was performed with
a couple of forces. The initial rotational force varied between 200 to 300 grams/mm. Mean rotation time was 12weeks. After complete derotation, all transplant s were integrated into a fixed appliance for leveling and approximal space closure. Average Orthodontic treatment time was 15.2 months.
In vertically atrophied jaw sections, transplants were fixed in distinct infraocclusion (average 5.1 mm). Transplants were leveled to the occlusal plane before closing the approximal spaces. Mean orthodontic treatment time was for 14.4months.
For determining pulpal and periodontal conditions, clinical and radiologic examinations were carried out. Autotransplanted third molars or wisdom teeth without subsequent orthodontic treatment had the best pulpal and periodontal results. All transplants were at the developmental stage with their open apices providing a high chance of pulp revascularization.
The results suggest that orthodontic extrusion and minor lateral tooth movement have no harmful effects on the pulpal and periodontal condition of autotransplanted immature third molars or wisdom teeth. Atrophy of the alveolar process did not affect pulpal and periodontal healing of the transplants in the extrusion group. A certain amount of spontaneous eruption had occurred in most patients by the time orthodontic treatment began. The formation of new alveolar processes wasobserved during subsequent orthodontic treatment.
Revascularisation started on the fourth postoperative day with an in growth of new vessels and was usually completed after 30 days, with the entire pulp containing new vessels. In contrast to pulpal revascularization, first signs of pulpal reinnervation cannot be demonstrated until at least a month after transplantation and are limited to the apical part of the pulp. Even after 2 years, the restored pulpal nerves are described as sparse, and the new axons are small in diameter. By postponing the onset of orthodontic treatment to the third to sixth month after transplantation and slower derotation of multi rooted transplants might increase the success rate.