developmental dental disorders may be due to abnormalities in the differentiation of the dental lamina and the tooth germs ( anomalies in number , size and shape ) or to abnormalities in the formation of the dental hard tissues ( anomalies in structure ) . in some , both stages of differentiation are abnormal .
developmental dental disorders are not only congenital but they may also be inherited , acquired or idiopathic . the terms  double tooth  ,  double formations  , joined teeth  , or  fused teeth  are often used to describe gemination and fusion , both of which are primary developmental abnormalities of the teeth.17 in the primary dentition , the frequency of gemination or fusion is about 2.5% .
a survey of the literature has revealed prevalence estimates for bilateral double teeth ranging from 0.01 to 0.04% in the primary , and 0.05% in the permanent dentition.1,7 gemination is defined as an attempt to make two teeth from one enamel organ .
this results in a structure with two completely or incompletely separated crowns with a single root and root canal .
occasionally we see complete cleavage or twinning ( two teeth from one enamel organ ) .
the etiology is unknown , but trauma has been suggested as a possible cause , though a familial tendency has been suggested.8 gemination is observed in the deciduous as well as in the permanent dentition.3,4,7 in the anterior region , this anomaly can cause unpleasant esthetic appearance due to irregular morphology . if a deep groove is present , these teeth may be susceptible to caries and periodontal disease and may require endodontic intervention in some cases which may be complicated.1,2 gemination usually present asymptomatically .
in fact , the co - operation of practitioners with expertise in multiple areas of dentistry is important to create or achieve functional and esthetic success in these cases .
several treatment methods have been described in the literature with respect to the different types and morphological variations of fused teeth , including endodontic , restorative , surgical , periodontal and/or orthodontic treatment.1,2,4,911 in clinical situations , cases of fusion have the appearance of a congenitally missing tooth , while in gemination the number of teeth in the dentition is normal , provided the double tooth is counted as one unit.1,4 this paper reports aesthetic rehabilitation of a rare case ; bilateral gemination of permanent maxillary central incisors utilizing heat - pressed lithium disilicate all ceramic crowns .
the patient complained about the large , unsightly maxillary central incisors , lip irritation and incising problems .
the patient did not complain of previous painful symptoms in that region and his medical and dental histories were unremarkable .
clinical examination revealed the presence of an irregular bilateral morphology of the permanent maxillary central incisors .
the maxillary dental arch presented two large central incisors that were abnormally wide and bifid crowns .
the incisors showed a buccal and palatal groove from the incisal edge to the cervical portion of the tooth .
an initial caries lesion was noted on the labial groove of the right incisor , along with gross plaque accumulation ( figure 1 ) .
the left central incisor was caries - free , as were all other erupted teeth had no restoration in the panoramic radiographic examination but only first molars had proximal caries which are restored before the prosthetic treatment procedure ( figure 3 )
. left and right maxillary central incisors were found to be free from periodontal disease .
treatment plans for the patient included all ceramic crowns for the upper incisors and canines .
after administering local anesthesia , preparations were made in the incisal , buccal , mesial , distal and palatinal surface of each of the clinical crowns in left and right maxillary central incisors , laterals and canines ( figure 4 ) .
anatomic preparations were conducted , especially in the distal portions of the maxillary central incisors wider preparations carried out in order to eliminate the amorphous shape of the maxillary central incisors .
the impressions of the prepared teeth were obtained utilizing polyether based elastomeric impression material ( impregum penta h , duosoft grant l , duosoft , 3 m espe , germany ) after casting the model , all ceramic cores manufactured utilizing heat - press ceramic technique ( ips empress 2 , ivoclar , schaan , liechtenstein ) with # 100 lithium disilicate ceramic ingots .
after the heat - press procedure completed ceramic cores were ready for try in procedures ( figure 5 ) .
final restoration conducted by layering technique ( empress 2 dentine ivoclar , schaan , liechtenstein ) .
all ceramic crowns were bonded to the prepared abutments using dual cure composite resin luting cement ( rely - x arc , 3m - espe , germany ) .
these fixed restoration treatment resulted in marked improvement in the esthetics of the anterior region and also enhanced periodontal health ( figure 6 ) .
the patient was encouraged to practice strict oral hygiene . after a 3-month period , the patient returned for evaluation . at the 1-year recall appointment ,
the terminology dental fusion and gemination are used to define two different morphological dental anomalies , characterized by the formation of a clinically wide tooth . despite the considerable number of cases reported in the literature ,
case history and clinical and radiographic examinations can provide the information required for the diagnosis of such abnormalities.1,36,12 after a judicious evaluation of all information we can report that this case represents bilateral gemination of maxillary incisors . while the literature on the occurrence of double teeth is extensive , there is still much discussion concerning the nomenclature .
some authors have tried to differentiate them by counting the teeth or by observing the root morphology : others use fusion and gemination as synonyms .
finally , some authors simply call the phenomenon  double teeth  or  connoted teeth  to avoid confusion over terminology.9,10 the use of levitas classification to distinguish between cases of fusion and gemination is very practical.9 the differential diagnosis between fusion and gemination , based on the number of teeth present on the dental arch , is not , however , always possible.5 this is because nothing impairs the fusion between a  normal  and a supernumerary element while the contiguous  normal  tooth is congenitally absent , resembling clinical cases of gemination.5,6 the phenomenon of gemination arises when two teeth develop from one tooth bud and , as a result , the patient has a larger tooth but a normal number , in contrast to fusion where the patient would appear to be missing one tooth.3,4,6,7 fused teeth arise through union of two normally separated tooth germs , and depending upon the stage of development of the teeth at the time of union , it may be either complete or incomplete .
however , fusion can also be the union of a normal tooth bud to a supernumerary tooth germ . in these cases ,
the number of teeth is also normal and differentiation from gemination may be very difficult , if not impossible . in geminated teeth , division is usually incomplete and results in a large tooth crown that has a single root and a single canal.1,3,5 this anatomic irregularity occurs more often in the deciduous than in the permanent dentition .
only a few cases of fusion involving molar and premolar teeth have been reported whereas , in both dentitions , the prevalence is higher in the anterior region.3,4,6,8,9 cases of bilateral fusion are less frequent than unilateral fusion .
the anomaly can cause unpleasant esthetic appearance due to irregular morphology . when deep grooves are present , these teeth may be susceptible to caries and periodontal disease and may require endodontic intervention in some cases which may be complicated.3,4,12,13 the main periodontal complication in gemination cases occurs due to the presence of fissures or grooves in the union between the teeth involved . if these defects are very deep and extend subgin - givally , the possibility of bacterial plaque accumulation in this area is quite high .
furthermore , gemination may have an adverse effect on occlusion , causing deviation and , sometimes , delaying the eruption of other teeth with aesthetic problems resulting from tooth.2 in this case , despite of the buccal grooves in the maxillary centrals no serious periodontal disease was evident .
the double teeth in the cases studied were mostly unilateral , involving two adjacent teeth .
no difference was found in the proportion of double teeth in either the maxilla or mandible.1,2,6 in this case bilateral gemination was seen in maxilla which caused esthetic problems .
difficult cases include a wide spectrum of problems.912 the best way to manage these difficult cases depends on a number of factors including the knowledge and technical skills of the practitioner.1,913
in this case , restoration of all the six maxillary anterior teeth was preferred due to the wide and amorphous shape of maxillary central incisors .
for esthetic satisfaction , wideness of these teeth was divided and distributed and was shared among the lateral incisors and the canines .
 geminated teeth are the consequences of developmental anomalies leading to the eruption of joined elements . 
 according to current definitions , gemination occurs when one tooth bud tries to divide , while fusion occurs if two buds unite . 
 clinical experience shows , however that diagnosis can be complicated due to superimposed anomalies . 
 this report describes a unique case of bilateral gemination of permanent maxillary central incisors . 
 the esthetic rehabilitation of the geminated incisors accomplished utilizing all ceramic crowns . 
 it is important that in these types of cases , reaching to the available esthetics and avoiding the complication of caries and periodontal problems with prosthetic application is satisfactory . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSIONS