the incidence of tooth abnormalities in children with cleft lip and palate is higher than that in children without clefts3,5,16 .
tooth abnormalities reported in the literature are related to the number , size , shape and eruption of teeth3,8,16 .
disturbances involving anomalies in tooth eruption are called ectopia and may be observed in several regions around the oral cavity , as well as in other areas of the human body .
there are reports of teeth in the maxillary sinus , mandibular condyle , coronoid process , orbit , palate , mentum and skin .
teeth have also been found in unusual sites , including the ovaries , testicles , anterior mediastinum , retroperitoneal , sacral and coccygeal areas4,6,7,10,12,13 .
transmigration or migration is the term assigned to ectopia when teeth are present in areas distant from the alveolar process2 .
the term unerupted tooth is used to designate a tooth that presented failure in eruption as a result of malpositioning , delayed eruption or impaction23 .
the term dental migration may indicate the movement of an unerupted tooth to an area far from its regular place of development
. this denomination does not refer to displacement of a totally or partially erupted tooth to an abnormal position in the dental arch . according to peck ( 1998 )
, dental migration refers to the horizontal movement of unerupted teeth and occurs only in the mandible .
the unerupted teeth most frequently presenting migration are the premolars15,22 , with predominance of females over males11,22 , canines15,22 , and mandibular 3rd molars22 .
intraosseous migration of premolars is less frequently found in the literature than migration of the canine .
the first description of migration of mandibular 1st molar was published by shields19 in the early 1900 's . since then
later reports presented cases of migration of the mandibular 2nd premolars due to early loss of the permanent mandibular 1st molars10,11,15,18,20,22 .
matteson , et al.11 , ( 1982 ) reported the importance of the knowledge of the mechanism of tooth eruption to understand ectopic migrations , which aids in the diagnosis , prevention and treatment of these occurrences .
sutton22 ( 1968 ) suggested that the initial angulation of the tooth and frequent loss of primary mandibular 1st molars are important for distal migration of mandibular premolars .
however , peck15 ( 1998 ) suggested that canine migration may have a genetic cause based on observation of cases of bilateral migration , while migration of premolars is either casual or idiopathic , rather than genetic .
distal migration is not yet completely known , since the teeth tend to present mesial movement due to masticatory efforts .
the chance of intraosseous migration of the 2nd premolar is significantly increased in case of early loss of the permanent 1st molar , that is , before eruption of the 2nd premolar .
after loss of the permanent mandibular 1st molar , the possibility of distal migration of the mandibular 2nd premolar ranges from 5 to 10%11 .
mandibular 2nd premolars presenting severe migration from their usual site to the region mesial to the permanent mandibular 2nd molar , where it then erupts normally , are named paramolar - wanderung 
 1 .
however , decision on surgical removal depends on the symptoms reported by the patient , the site where the tooth is found , and presence or not of associated pathologies .
surgical removal can be performed via intraoral or extraoral access with care to avoid damage to the inferior alveolar nerve or jaw fracture9,6,12 . even though the occurrence of tooth abnormalities is higher in permanent teeth ,
they have also been reported in the primary dentition , more frequently in children with cleft lip and palate3,16,5 .
no reported case of migration of mandibular teeth in patients with cleft lip and palate was found in the literature .
this paper presents a case report of migration of the mandibular left 2nd premolar in a patient attending the hospital for rehabilitation of craniofacial anomalies of the university of so paulo ( hrac / usp ) , brazil .
the patient m. c. f. a. , a 4-year - year - old female child with bilateral complete cleft lip and palate , first attended the hospital for rehabilitation of craniofacial anomalies of the university of so paulo ( hrac / usp ) in 1976 for clinical and surgical treatment .
it was observed that the patient presented normal aspect of the tooth buds of maxillary right and left 1st premolars , mandibular left 1st and 2nd premolars , and mandibular right 1st premolar .
the maxillary right and left 2nd premolars and mandibular right 2nd premolars were congenitally absent ( figure 1 ) .
a new radiograph was taken at the age of 8 , which revealed abnormal angulation of the tooth bud of the mandibular left 2nd premolar , whereas the other teeth presented normal eruption pathway ( figure 2 ) .
when the patient was 11 years old , the tooth bud of the mandibular left 2nd premolar presented an horizontal position in relation to the midsagittal plane .
the other teeth were erupted , except for the maxillary and mandibular right and left 2nd molars , which were in the course of eruption ( figure 3 ) . at the age of 12 ,
the tooth bud of the mandibular left 2nd premolar was positioned ectopically and had its crown impacted against the mesial root of the mandibular left 1st molar ( figure 4 ) .
three years later , a periapical radiograph of the mandibular left 1st molar was obtained and extraction of the mandibular left 1st molar was planned ( figure 5 ) .
surprisingly , only 2 months after extraction , the mandibular left 2nd premolar presented distal migration , still in a horizontal position in relation to the midsagittal plane , reaching the area of the mandibular left 3rd molar ( figure 6 ) .
two - year radiographic follow - up revealed that the mandibular left 2nd premolar was migrating to the mandibular ramus , without any symptomatology .
the root apices were positioned in the retromolar area and the crown was located in the mandibular ramus ( figure 7 ) . a panoramic radiograph taken at the age of 23 ( figure 8) showed that the mandibular left 2nd premolar was positioned in the mandibular notch area .
the last radiograph was taken when the patient was 30 years old ( figure 9 ) .
the prevalence of intraosseous migration of premolars is low compared to other teeth , such as canines15 .
this case report shares some characteristics with reports in the literature . in this case ,
when the patient was 8 years old , the tooth bud of the mandibular left 2nd premolar presented an abnormal angulation .
there was also early loss of the mandibular left 1st molar at the age of 15 , which allowed distal migration of the mandibular left 2nd premolar .
these events agree with those reported by sutton22 ( 1968 ) , matteson , et al .
11 , ( 1982 ) , loh and ho10 ( 1986 ) , jasmin7 ( 1989 ) , spyropoulos20 ( 1990 ) , peck15 ( 1998 ) , and shapira and kuftinec18 ( 2003 ) .
it may be inferred that the association of these two factors was determinant for distal migration of the mandibular 2nd premolar .
thus , if early diagnosis of this situation is established , the dentist may initiate the treatment before the tooth reaches a more difficult access . in the present case ,
the ectopic mandibular left 2nd premolar moved to the mandibular notch , differently from the cases reported by loh and ho10 ( 1986 ) and infante - cossio , et al.,6 ( 2000 ) , who reported dental migration to the mandibular angle ; orton and mcdonald13 ( 1986 ) , jasmin , et al.7 ( 1989 ) and okada , et al.12 ( 2002 ) , who described migration to the coronoid process ; loh and ho10 ( 1986 ) , who reported migration to the ascending mandibular ramus ; and okada , et al.12 ( 2002 ) , who described migration to the mandibular condyle .
treatment for this type of anomaly varies according to the position and conditions presented by this tooth , as well as the presence of any discomfort to the patient . in the present case ,
it was decided not to extract the mandibular left 2nd premolar , since it did not cause discomfort to the patient or any evidence of alteration , as reported by infante - cossio and hernandez - guisado , gutierrez - perez6 ( 2000 ) and okada , et al.12 ( 2002 ) . however , lehman9 ( 1987 ) recommended the extraction of ectopic teeth with evidence of cyst associated with the tooth crown .
it may be concluded that intraosseous distal migration of the mandibular left 2nd premolar associated with cleft lip and palate is a rare condition , since no previous reports were found in the literature .
however , the present case demonstrates that it occurred in a similar manner as in individuals without clefts .
the presence of intraosseous distal migration seems not to be directly related with the presence of cleft lip and palate .
 disturbances involving abnormalities in tooth eruption are named ectopia . 
 transmigration is the name assigned to ectopia in the presence of teeth in areas distant from the alveolar process . 
 initial angulation of the tooth bud of the second premolar and premature loss of permanent mandibular 1st molars can influence the distal migration of the second premolar . 
 some studies have observed that ectopic teeth can be found in a variety of places around the oral cavity and also in other areas of the human body . 
 there are records of teeth in the maxillary sinus , mandibular condyle , coronoid process , mandibular angle , orbit , palate , mentum and also the skin . 
 the prevalence of tooth abnormalities is higher in children with cleft lip and palate compared to children without clefts . 
 this paper presents a case report of migration of the mandibular left second premolar in a patient attending the hospital for rehabilitation of craniofacial anomalies of the university of so paulo ( hrac / usp ) , brazil . 
 migration of the mandibular left 2nd premolar was confirmed by 8 panoramic and 1 periapical radiographs obtained during patient 's treatment between 1978 and 2002 , which were available in the files of the department of dental radiology of hrac / usp . 
 it can be assumed that distal migration of the mandibular left 2nd premolar is not associated with presence of cleft lip and palate ; observation of these two events in a same patient is rare , since no similar reported cases were found in the literature . 
INTRODUCTION AND LITERATURE OVERVIEW
CASE REPORT
DISCUSSION
CONCLUSIONS