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Print version ISSN 1698-4447
Med. oral patol. oral cir. bucal (Ed.impr.) vol.10 no.5 Valencia Nov.-Dec. 2005
Morbidity of third molar extraction in patients between 12 and 18
years of age
Morbilidad de la extracción de los terceros molares en pacientes entre los 12 y 18 años de edad
Angie Virginia Chaparro Avendaño (1), Silvia Pérez García (1), Eduard Valmaseda Castellón (2),
Leonardo Berini Aytés (3), Cosme Gay Escoda (4)
(1) Odontóloga. Máster de Cirugía e Implantología Bucal. Facultad de Odontología de la Universidad de Barcelona
(2) Odontólogo. Máster de Cirugía e Implantología Bucal. Profesor asociado de Cirugía Bucal.
Profesor del Máster de Cirugía Bucal e Implantología Bucofacial. Facultad de Odontología de la Universidad de Barcelona
(3) Médico Estomatólogo. Cirujano Maxilofacial. Profesor Titular de Patología Quirúrgica Bucal y Maxilofacial. Subdirector del
Máster de Cirugía Bucal e Implantología Bucofacial. Facultad de Odontología de la Universidad de Barcelona
(4) Médico Estomatólogo. Cirujano Maxilofacial. Catedrático de Patología Quirúrgica Bucal y Maxilofacial.
Director del Máster de Cirugía Bucal e Implantología Bucofacial. Facultad de Odontología de la Universidad de Barcelona.
Servicio de Cirugía Bucal, Implantología Bucofacial y Cirugía Maxilofacial del Centro Médico Teknon
Received: 16-01-2005 Accepted: 7-05-2005
|Chaparro-Avendaño A, Pérez-García S,Valmaseda-Castellón E, Berini-Aytés L, Gay-Escoda C.
Morbidity of third molar extraction in patients between 12 and 18
years of age. Med Oral Patol Oral Cir Bucal 2005;10:422-31.
© Medicina Oral S. L. C.I.F. B 96689336 - ISSN 1698-4447
Objective: An analysis is made of the incidence of complications following third molar surgical extraction in patients between 12 and 18 years of age.
Key words: Prophylactic extraction, third molar germenectomy, complicat
Objetivo: El propósito de este estudio fue analizar la incidencia de complicaciones después de la extracción quirúrgica de los terceros molares en pacientes de 12 a 18 años de edad.
Palabras clave: Extracción profiláctica, germenectomía del tercer molar, complicaciones.
Third molars present a high incidence of impaction, and have been associated with the appearance of disorders as diverse as pericoronitis, caries of the distal surface of the second molar or of the third molar itself, myofascial pain, certain types of cysts and odontogenic tumors, and primary or secondary dental crowding (1).
Difficulties in third molar eruption, particularly of the lower molars, are attributable to their late formation and to the phylogenetic evolution of the mandible, which results in a lack of available space for normal eruption (2).
To date, no model has been able to reliably predict whether a given molar will erupt or become retained (3). As a result, it may be affirmed that prophylactic extraction of the third molar germ is decided on an empirical basis. Such prophylactic extraction has been described as being beneficial for the patient, since it avoids the development of cystic or infectious problems (4, 5).
Nevertheless, in certain cases the third molar can erupt correctly without complications, and may even prove useful as an abutment for a prosthesis or orthodontic anchorage particularly if the first or second molar is missing (6, 7).
Accordingly, the prophylactic extraction of third molars should not be regarded as a routine therapeutic practice without first carefully assessing its true indications and cost-benefit ratio (6).
An additional source of debate is represented by the observation that third molar germenectomy appears to involve less morbidity than extraction carried out when molar root formation has been completed (6).
The present study analyzes the incidence of complications following third molar surgical extraction in patients in the 12-18 years age range, with an evaluation of the association of such complications to patient age and sex, the reason for extraction, the degree of dental development, and third molar position, angle and impaction.
PATIENTS AND METHOD
A retrospective study was made of 173 patients subjected to third molar surgical extraction (120 upper and 270 lower third molars) in the Master in Oral Surgery and Implantology of Barcelona University Dental School (Spain), during the period between January and December 2000. The clinical history was reviewed in all cases, and patient age (12-18 years) at the time of extraction was recorded. The patients were divided into three groups: A (12-14 years), B (15-16 years) and C (17-18 years).
Additional study variables comprised patient sex, the reason for extraction, and the Nolla third molar calcification stage (8) assessed from orthopantomography and classified as either Nolla stage ≤6 or ≥7. Likewise, the depth of the third molar in relation to the occlusal plane (A, B, C) was documented, along with the distance between the vertical mandibular ramus or upper maxillary tuberosity and the distal surface of the second molar (Class I, II, III) according to the classification of Pell and Gregory (9). Molar angulation with respect to the longitudinal axis of the second molar (mesial angulation, distal angulation, vertical and horizontal) was recorded based on the classification of Winter (10). Finally, the appearance of postoperative complications was documented.
The data were processed using the SPSS version 9.0 statistical package (Barcelona University license). The Pearson chi-square test was used to assess the association between qualitative variables and the appearance of postextraction complications. The linear trend chi-square test was applied in the case of qualitative variables with more than two categories (the latter moreover being ordinal). The relation between patient age and the appearance of complications was in turn evaluated by the Student t-test for independent samples.
One third molar was extracted in each surgical procedure, based on a standardized technique (11) under local anesthesia (4% articaine with epinephrine 1:100,000). A carpule (1,8 ml) was injected into the mandible for inferior alveolar and lingual nerve truncal block, by the direct approach, using a long 38-mm needle with a short bevel, and infiltrating the bucal fold (buccal nerve) with half an anesthetic carpule.
A triangular mucoperiosteal flap was then raised by distal incision over the retromolar trigone and release (generally mesial to the second molar). In some cases no vertical releasing incision proved necessary.
The ostectomy was carried out using a sterile low-speed handpiece with a number 8 rounded tungsten carbide drill under irrigation with sterile distilled water. Sectioning of the dental crown and/or roots was carried out where necessary.
In the upper jaw, 1,5 ml of anesthetic carpule was injected into the bucal fold to block the superior posterior alveolar nerve, while 0,3 ml was administered palatal at the height of the second molar to block the anterior palatine nerve. A mucoperiosteal flap was raised via distal incision with vertical release extending to the mesial aspect of the second molar. The corresponding ostectomy was performed in the same way as described above.
Luxation and avulsion was carried out using straight and Pott elevators. This was followed by careful alveolar curettage and irrigation with abundant sterile distilled water.
Lastly, the flap was repositioned and sutured using an atraumatic C16 needle and 3/0 silk.
All patients received postoperative instructions and medication (generally amoxicillin 750 mg 3 times daily for 7 days, oral sodium diclofenac 50 mg 3 times daily for 5 days, metamizol 575 mg every 6-8 hours for 3-4 days, with 0.12% chlorhexidine digluconate rinses 3 times a day for 15 days). After 7 days, a surgeon removed the suture.
A total of 390 third molars (120 upper and 270 lower third molars)were extracted in 173 patients.
Most surgical extractions corresponded to female patients and represented 66,9% of surgical procedure (figure 1).
About 63% of all extractions corresponded to Group C (figure 2).
Globally, third molar extraction was most often indicated for orthodontic reasons (40,5%), involving patients with fixed orthodontic treatment, or who had worn it in the past, to prevent anterior crowding relapse.
Extraction for prophylactic reasons (39.5%) was decided due to a lack of space, or because the presence of the third molar constituted a potential threat for the periodontal health of the second molar. The existence of clinical manifestations (pericoronitis, pain, etc.) was the cause of extraction in 20% of the total cases.
In the case of the upper third molars, prophylaxis was the most frequent reason for extraction (49,2%), in contrast to the lower third molars where the most common indication was orthodontic (38,9%).
The most frequent Nolla dental calcification stage for both the upper and lower third molars was 7 (one-third of the root completed).
Regarding the depth of the upper third molar with respect to the occlusal plane of the second molar, 75% were located above the cementoenamel junction of the upper second molar (depth C). In the case of the lower third molars, 46,7% were located below the cementoenamel junction of the second molar (depth C).
Third molar angulation with respect to the longitudinal axis of the second molar was evaluated from orthopantomography. Eighty percent of the upper third molars presented vertical angulation, while 13,3% showed mesial angulation and 6,7% were angled distally. In comparison, 71,5% of the lower third molars showed mesial angulation, 27% were vertical, and 1,5% presented distal inclination.
Regarding the distance from the second molar to the upper maxillary tuberosity, 47.5% of the upper third molars presented impaction Class I (sufficient space between the distal aspect of the second molar and the upper maxillary tuberosity). As to the distance from the lower second molar to the vertical mandibular ramus, 56,7% of the third molars presented impaction Class II (distance between the vertical mandibular ramus and the lower second molar inferior to the mesiodistal diameter of the third molar).
The postextraction complications rate was 15,62% or the global 390 third molar extractions performed. All such complications were mild and reversible, and comprised persistent swelling and pain (8,9%), secondary infection (1,8%), difficulty in opening the mouth (2,3%, and ecchymosis (2,1%). One case each of inferior alveolar nerve paresthesia (0,26%) and lingual nerve paresthesia (0,26%) was recorded, in Group C. These paresthesias completely resolved after one and two months, respectively.
The incidence of complications in Groups A, B and C (i.e., 12-14, 15-16 and 17-18 years of age) was 17,4%, 19% and 13,7%, respectively (p = 0,308) (Table 1).
In terms of patient sex, complications were more frequent in females (18%) than in males (9,3%) (p = 0,033) (figure 3).
As regards the reasons for extraction, the group of patients in whom extraction was indicated for prophylactic reasons accounted for 11,7% of the complications, while extraction for orthodontic reasons and because of the appearance of clinical manifestations in turn accounted for 18,4% and 17,9% of the complications, respectively. No statistically significant differences were observed between the reasons for extraction and the incidence of postoperative complications (p = 0.221).
The appearance of complications was greater in Nolla third molar calcification stage ≤ 6 (20,2%), though statistical significance was not reached (p = 0,093) (Table 2).
In relation to angulation, distally angled molars posed most complications (41,7%), followed by mesially inclined teeth (19,1%) and vertical molars (9,5%) (p = 0,048).
Molars presenting depth C accounted for 17,1% of the recorded complications, followed by those in position B (15,3%) and A (9,3%) the differences being nonsignificant (p = 0,430).
As regards third molar impaction with respect to the tuberosity of the upper maxilla and/or vertical mandibular ramus, upper third molars presenting Class III, II and I respectively accounted for 9%, 11,5% and 3,5% of the postextraction complications the differences being nonsignificant (p = 0,276). This contrasted with the situation in the case of the lower third molars, where the teeth presenting impaction Class III, II and I respectively accounted for 27,8%, 17,6% and 3,7% of the complications these differences being significant (p = 0,028).
Third molar germenectomy consists of extraction of the developing dental germ included within the maxillary bone. This procedure is usually carried out after age 12-13 years, which is when the tooth is in the initial calcification stages. The operation is indicated when is expected that insufficient space will be available for correct eruption, or when malpositioning of these molars is observed. The affected subjects are commonly children subjected to orthodontic treatment in which early extraction is indicated to avoid interferences with the treatment (crowding, altered second molar eruption, etc.). The best time for extraction is at the end of vertical mandibular ramus reabsorption (generally at age 17 in boys and 15 in girls) (12).
The third molars, and particularly those in the lower jaw, are the most frequently impacted teeth (11), with an incidence of between 9,5% and 39%, depending on the source (13, 14).
Controversy exists over the extraction of third molars which have caused no pathology at all. This subject has been addressed by different studies designed to clarify the indications of such treatment (1, 4, 5, 7). The authors who advocate molar extraction in the germ phase (between 14-18 years of age) consider such extraction to afford a number of advantages: the surgical procedure is easier, early prevention of impaction against the second molar is achieved, the appearance of clinical complications in adulthood is avoided (e.g., pericoronitis), and postoperative recovery in the adolescent is more favorable than in adults (4, 5).
Gay-Escoda and Berini define the best timing for prophylactic extraction as the moment when one-half to two-thirds of the molar roots have formed, this generally occurring between 16-18 years of age. In any case, preventive extraction is indicated up to age 25, since the bone is less mineralized (elasticity and resilience) and the periodontal ligament is not yet fully formed (2).
Sentilhes (15) considers that patient age should not be taken into account, and that evaluation should only be made of the degree of third molar mineralization and the available space at age 14, to avoid the eruptive outbreak (coinciding with mineralization of the apical third) and thus indicate extraction before complications occur. Colmenero et al. (16) advise early extraction of the germs of symptomatic third molars. Moreover, in the case of teeth that do not present symptoms, they consider it best to wait until age 25-26 to see whether spontaneous eruption occurs. Virgili et al. (17) in turn consider that third molars should be extracted in the face of a first episode of pericoronitis. Lytle (18) advocates early extraction of the germs of third molars impacted against the second molars, since the younger the patient the faster the formation of bone within the postextraction defect thereby significantly reducing the risk of formation of a periodontal pouch distal to the second molar after extraction. Likewise, Kugelberg (19) has shown that distal attachment loss of the second molar after lower third molar extraction is less pronounced in young patients.
However, Chiapasco et al. (6) recommend a more conservative approach and consider that a third molar germenectomy should be made after duly assessing the cost/benefit ratio. Among the indications for extraction, they propose morphostructural alterations or ectopic impactions; the impossibility of molar eruption due to dysplastic alterations of the germ or mandibular pathology; the gaining space in the posterior segment when distalization of the first and second molar is required; and in the event of excessive anteroposterior mandibular growth or severe dentoalveolar discrepancy.
Before extracting a third molar germ, the possibilities for long-term eruption should be evaluated. While different methods have been developed to predict whether a molar will erupt or become impacted, no criteria currently exist for predicting the outcome with certainty (3).
Few studies have addressed morbidity following third molar germenectomy (6, 20). The complications commonly described in adults after third molar extraction are persistent bleeding, delayed healing, dry socket, the formation of abscesses and nerve alterations (inferior alveolar and/or lingual nerve) (22-23).
In adults, the incidence of dry socket ranges from 0,5-30% (4, 21), secondary infection 1,5-5,8% (21), and persistent bleeding from 0,6-5,8% (4, 18). A high incidence of excessive bleeding has been described in relation to distally angled molars with deep impaction and in patients over age 25 years (22).
Bjornland et al. (20), following 172 germenectomies, reported an incidence of dry socket of 1,8%, with a secondary infection rate of 1,7%. Similar results have been obtained in our own study, with a 1,8% of secondary infections that subsided after 7-15 days.
In the present series most patients subjected to extraction were females (66,9%). Likewise, females were more prone to develop postoperative complications (p = 0,033). Similar observations have been reported by Fisher et al. (23) and Larsen et al. (24).
The complications rate after molar extraction is reported to be 10% (35). Chiapasco et al. (6) observed a complications rate of 2,6% in patients in the 9-16 years age range, versus 2,8% in patients aged 17-24 years, and 7,4% among those over age 24. Pons et al. (26) reported complications in 6,4% of cases after lower third molar removal in patients aged 13-16 years. In the present study, complications were observed in 17,4% of the patients aged 12-14 years, versus in 19% and 13,7% of patients aged 15-16 and 17-18 years, respectively.
Nevertheless, in order to contrast results, the definition of complications must be taken into account, since the figures differ considerably according to the criteria used by different authors.
In this sense, some authors (23, 27, 28) have found no differences in pain, swelling or mouth opening difficulties in relation to patient age. In contrast, others (4, 22) have shown that as patient age increases, pain (26, 28), swelling (4) and mouth opening difficulties increase (4, 22). In our series we found pain, swelling, infection, mouth opening difficulties and ecchymosis to be more problematic at younger ages, while increasing patient age was associated to an increased risk of inferior alveolar and/or lingual nerve sensory alterations.
One advantage of lower third molar germenectomy is that it is less likely to cause inferior alveolar nerve paresthesias, since the roots of the tooth have not yet been fully formed, and therefore the relation to the alveolar nerve is inexistent or at least much less evident than in adults (6). The incidence of inferior alveolar nerve damage after third molar extraction varies from 0,3% to 8% (4, 21, 29, 30). An earlier study by our group revealed a 1.3% incidence of inferior alveolar nerve injuries (95% confidence interval 0,8-2,2%) (30). In the present study, one case of inferior alveolar nerve paresthesia was documented, representing 0,3% (95% confidence interval 0,09-2,0%).
The incidence of lingual nerve damage when adopting the vestibular approach varies from 0-10% (21, 31, 32). In the present study one case of lingual nerve paresthesia was recorded, likewise representing 0.3% (95% confidence interval 0,09-2,0%).
The intensity and duration of postoperative pain has been shown to increase with the difficulty and duration of surgical extraction. On the other hand, Fisher et al. (23) have reported no relation between patient age, the duration of surgery, the surgical skill of the operator, the presence or absence of pericoronitis and the degree of impaction in relation to pain appearing in the first hours after lower third molar extraction.
The presence of signs and symptoms - particularly pericoronitis - has been considered a risk factor for the development of complications (20). In the present series no relation was found between the presence of clinical manifestations and an increased incidence of complications, however.
An increased incidence of complications was recorded in patients with Nolla third molar calcification stage ≤6 (20,2%). This can be explained by the greater ostectomy required for extraction in such cases (p = 0,093).
As to molar angle, distally inclined molars posed most complications (41,7%), followed by mesially inclined teeth (19,1%) and vertical molars (9,5%) (p = 0.048). This situation may be due to the increased ostectomy needed in view of the existing dental impaction.
The deeper the molar increases the difficulty of extraction, the duration of the operation and the associated swelling and mouth opening difficulties (33). In our series the molars presenting depth C presented greater complications (17,1%), though statistical significance was not reached (p = 0,430).
Finally, regarding the relation of the third molar to the vertical mandibular ramus, extraction difficulty progressively increases from Class I to III (34). In our study, higher Class ratings in relation to the vertical mandibular ramus were significantly associated to greater pain, swelling and mouth opening problems (p = 0,028). Likewise, in upper molars presenting impaction Class II and III, a nonsignificant increase in the incidence of complications was recorded (p = 0,276).
• The present study shows no statistically significant differences in the frequency of postextraction complications in the three age groups contemplated. Younger ages are associated with increased pain, swelling, ecchymosis and mouth opening difficulties, though in contrast increasing patient age is associated to an increased risk of inferior alveolar and/or lingual nerve sensory alterations.
• The presence of clinical manifestations exerts no influence in terms of an increase in postoperative complications.
• Females are seen to exhibit a greater frequency of postextraction complications.
• The less the space available for eruption (Class I, II, III of the classification of Pell and Gregory), the greater the risk of postoperative complications.
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