Should third molars be extracted prophylactically for orthodontic stability?



There has been a batch of talk over the last few decennaries about the controversial topic of how the presence of 3rd grinders and their eruptions can impact condescending stableness and most significantly late anterior crowding. However, to forestall the dentition from switching after braces, people are still normally referred to hold their wisdom dentitions extracted.1 In malice of many researches, the function of 3rd grinders in the development of late incisor crowding is non wholly understood.1A Throughout many researches, several etiologic factors sing late front tooth herding have been found which in major are dwelling of anterior growing and remodelling of the mandible 2, mesial migration of posterior dentitions, anterior constituent of force on occlusion 3, grade of original herding 4, and tooth size and shape.5 Another factor that at some point has been taken into history is the place and the eruption tract of 3rd molars.6 Because late crowding largely happens at about the same age as the 3rd grinders erupt, besides in most instances those 3rd grinders are impacted because of unequal growing of the organic structure of the mandible and really unequal remodelling of the anterior boundary line andA bone deposition in the posterior boundary line of the ramus of the mandible, it had been concluded by the tooth doctors and the patients in generalA that the presence of 3rd grinders along with unequal infinite for their eruption will do late incisor crowding. 7 Furthermore, in some people with congenitally losing 3rd grinders, tardily lower incisor crowding is besides evident.7 Although some Centres report that more than 50 % of 3rd molar remotions are performed for orthodontic considerations, there is really small scientific grounds to clear up the religion, hope and in many instances the charity that surrounds this question.8


several surveies have shown that there is non important correlativity between Orthodontic backsliding and the presence of inframaxillary 3rd grinders. Southard 9 concluded that remotion of unerupted inframaxillary 3rd grinders will non significantly relieve proximal contact stringency. The consequence of this survey explained that extraction of 3rd grinders purposefully to alleviate interdental force per unit area and accordingly forestalling inframaxillary incisor herding look to be unwarranted.9 Jones et al conducted a survey to find to which extent orthodontists should mention station orthodontic patients for 3rd lower molar remotion surgery.10 Ten orthodontists from infirmary, private patterns, community scenes were chosen for the survey. Participants were presented with 15 instance histories of orthodontic patients and asked to province whether they would hold referred the instance for extraction of those 3rd grinders. Of 300 determinations 262 ( 85 % ) were against mentioning instances for 3rd molar surgery. 10 Niek et Al ( 1995 ) reported a little and statistically important relationship with station intervention addition in herding which was on mean 1.3 millimeter greater in the presence of 3rd molars.11 However, in this survey some of the losing grinders were the consequence of agenesia instead than curative extraction. The job with this sort of surveies is that the developmental absence of 3rd grinders may besides differ genetically in other of import facets such as tooth or arch size which may besides hold a important impact on late incisor crowding.11

In a Randomized Control Trial survey conducted in U.K 11 ( 1998 ) 164 patients were selected. All patients had antecedently undergone orthodontic intervention but at the clip of entry to the survey they were no longer have oning any contraptions or considerations, and all patients had crowded 3rd grinders which their eruption were through the next 2nd grinder. The survey was done over a 66 month period, and merely forty-seven of patients completed the test. The consequence of the survey supports that the force per unit area from behind consequences in increased incisor abnormality, but besides supports that there is no important determination that this pressureA is chiefly influenced by 3rd molar extraction. Respectively, the function of 3rd grinders in bring forthing such force per unit area that could do incisor crowding remains ill-defined.

Bergstrom and Jensen 12 designed a survey to find the extent to which 3rd grinders are responsible for secondary tooth herding. They did aA cross sectional survey over 30 dental pupils who really had one-sided agenesia of upper 3rd grinders. Twenty-seven of those pupils besides had agenesia of one lower 3rd grinder. From plaster dramatis personaes, they compared the infinite conditions on both sides of each arch and the mesiodistal dissymmetries of the sidelong arch sections. They besides analysed midline supplanting. The consequences showed that there was more crowding in the quarter-circle where a 3rd grinder was present than in the quarter-circle with a losing 3rd grinder. Besides there was a mesial supplanting of the sidelong dental sections on the side with the 3rd molar nowadays in the inframaxillary arch but non in the upper jaw. It was besides noted that the one-sided presence of a 3rd grinder did non look to hold an consequence on the midplane. Bergstrom and Jensen concluded that the presence of a 3rd grinder seemed to hold some influence on the development of the dental arch but non to the extent that would warrant either the remotion of the tooth source, or the extraction of the 3rd grinders, other than in exceeding cases.

On the other manus, legion surveies found no correlativity between 3rd grinders and lower incisor crowding.13 Sidlauskas and TrakinienA- 14 The survey group consisted of 91 topics with an mean age 21.01A±4.13 old ages. The person, quantitative and cast based analytical enrollment of herding was based on the measurings of

mesiodistal breadth of dentitions and related to the length of the appropriate section of the lower dental arch. The survey resulted in no statistically important difference in lower alveolar consonant arch herding between the groups of erupted, unerupted and agenesia of 3rd grinders. However, the came up with three decision:1-The lower dental arch crowding is an indispensable characteristic of the completed lasting teething over the age of 17 old ages. 2- The 3rd grinders do non make statistically important difference of herding in the lower dental arch, when comparison subjects with the agenesia, removed and present 3rd grinders. 3- The recommendation to extraction 3rd grinders in the lower jaw has to hold justifiable ground and ca n’t be entirely based on the dubious principle to minimise present or future crowding of the lower anterior teeth.14A A A A A A

In another survey, Kaplan15 investigated whether inframaxillary 3rd grinders have a important influence on post-treatment alterations in the inframaxillary arch, specifically on anterior herding backsliding. He took the sample of 75 orthodontically treated patients on their pre-treatment, post-treatment, and 10 old ages post-retention survey theoretical accounts, and sidelong cephalograms were alsoA obtained. The sample was split into three groups: The first group was comprisingA of 30 individuals with both 3rd grinders erupted to the occlusal plane, in good alliance buccolingually, and of normal size and signifier. The 2nd group consisted of 20 individuals with bilaterally wedged 3rd grinders. All patients in this group were campaigners for surgical remotion of the 3rd grinders on the footing of post-retention periapical radiogram. The 3rd group consisted of 25 patients with bilateral agenesia of the inframaxillary 3rd grinders. Kaplan ‘s informations indicated that some grade of lower front tooth herding backsliding occurred in the bulk of instances. When the three 3rd molar groups were compared, nevertheless, there were no important differences in any of the parametric quantities examined. This was true whether bicuspids were extracted or non. Kaplan concluded that the presence of 3rd grinders does non bring forth a greater grade of lower anterior crowding or rotational backsliding after surcease of keeping Harmonizing to Kaplan, the theory that 3rd grinders exert force per unit area on the teeth mesial to them could non be substantiated.15


The form of growing of the jaws can act upon the comparative place of maxillary and inframaxillary teething. When the mandible grows frontward relative to the upper jaw, as it normally does in the late teens, every bit good as earlier, the mandibular incisor dentitions tend to be displaced lingually.7 The current construct is that late incisor herding about ever develops as the inframaxillary incisors, and possibly the full inframaxillary teething, move distally comparative to the organic structure of the mandible late in inframaxillary growing. This besides sheds some visible radiation on the possible function of the 3rd grinders in finding whether herding will happen, and how terrible it will be. If infinite were available at the distal terminal of the inframaxillary arch, it might be possible for all the inframaxillary dentition to switch somewhat distally, leting the lower incisors to upright without going crowded.7 On the other manus, wedged 3rd grinders at the distal terminal of the lower arch would forestall the posterior dentition from switching distally, and if differential inframaxillary growing occurred, their presence might vouch that herding would develop. As mentioned before, the extent of late inframaxillary growing is the cardinal factor, and tardily incisor herding which besides happens in persons with inborn losing 3rd grinders is non the critical variable. As we know mandible is about the last portion of the maxillofacial compartment which stops its growing. Nevertheless, the more theA growing of the mandible grows after other growing has basically stopped, the greater the hazard of lower incisor herding to happen.7

When contraceptive extraction of 3rd grinders are discussed, hazards and benefits have to be considered. Hazards of developing hurting, swelling, dry socket, parasthesia, station operative infection, shed blooding remain the most common station operative sequelae from 3rd molar surgery. Therefore, it is prudent to reserve the surgical process for instances that the patient will reliably benefit from.

Two consensus conferences were dedicated to the direction of 3rd grinders, one sponsored by the National Institute of Dental Research in 1979,16 and the other by the American Association of Oral and Maxillofacial Surgery in 1993,17 in an effort to make a general understanding on when and under what fortunes 3rd molar extraction is advised. Detailed studies on the countries of consensus were published but merely the countries related to orthodontias will be addressed here. Some of the points of consensus were:

  1. Crowding of the lower incisors is a multi-factorial phenomenon that involves a lessening in arch length, tooth size, form and relationship, narrowing of the inter-canine dimension, retrusion of the incisors, and growing alterations happening in adolescence. Therefore, it was agreed that there is small rationale based on the avail- able grounds for the extraction of 3rd grinders entirely to minimise present or future crowding of the lower anterior dentitions. If equal room is available for 3rd molar eruption, every attempt should be made to convey these dentitions into functional occlusion.
  2. Orthodontic therapy, in both maxillary and inframaxillary arches, may necessitate posterior motion of both first and 2nd grinders by either tipping or interlingual rendition, which can ensue in the impaction of 3rd grinders. To avoid impacting 3rd grinders and to ease abjuration, it may be deemed advisable in some instances to take 3rd grinders before get downing abjuration processs.


The influence of the 3rd grinders on the alliance of the anterior teething may be controversial, but there is no grounds to imply these dentitions as being the lone or even the major etiologic factor in the posttreatment alterations in incisor alliance. The grounds suggests that the lone relationship between these two phenomena is that they occur at about the same phase of development, Internet Explorer, in adolescence and early maturity. But this is non a cause and consequence relationship. The clinician has to hold a justifiable ground to rec ommend the extraction of any tooth.