dens invagination ( dens in dent ) ( di ) is a rare developmental anomaly of teeth with unclear etiology . several factors have been proposed for this phenomenon such as genetics , growth pressure of the dental arch , focal failure of growth of the internal enamel epithelium , distortion of the enamel organ , fusion of tooth germs , infection , and trauma . most authors consider that di results from an early infolding of the enamel organ into dentin papilla that can extend deep into the pulp cavity or roots or reach the apex . it can occur in any deciduous or permanent teeth , but the most commonly affected teeth are maxillary permanent lateral incisors , and it is less common in mandibular teeth and primary teeth . di is classified by oehler into three types to show the degree of malformation : type i represents an invagination confined within the crown ; type ii represents an invagination extended into the root ( beyond cementoenamel junction ( cej ) ) ending as a blind sac and may or may not connect to the dental pulp ; type iii represents an invagination that penetrates the root and forms an additional foramen and usually is not connected with the pulp . treatment plan depends on the type of di , its symptoms , and the age of the patient . when there is no communication between the invagination portion and the main root canal system , the aim of treatment is to prevent pulpal involvement to maintain the vitality of the pulp by sealing the orifice of the invagination , obturation of the dens with resin , or by conservative endodontic treatment of invagination as a separate entity . however , in these cases , although no radiographical or clinical communication between invagination portion and main canal seems to be present , there is histologically strong evidence of the dental tubule connections . different treatment methods are suggested such as conservative treatment , nonsurgical root canal therapy ( nsrct ) or combined root canal therapy ( rct ) and surgery , intentional replantation , and extraction . in the current report , invaginated portion was in contact with the main root canal . therefore , the endeavor was on removing the blind sac with diamond bur under the use of operating surgical microscope , so that the main root canal can be more accessible for cleaning and shaping and also the whole root canal can be obturated evenly . a healthy 25-year - old female patient with a history of a swelling in the right anterior palatal mucosa was referred to the endodontic department of isfahan university of medical sciences . intraoral soft tissue examination revealed a swelling in the palatal mucosa next to tooth # 7 and the missing of upper right canine ( # 6 ) . the crown of the affected tooth ( # 7 ) was peg shape with sides converging or tapering together incisally . the peg - shaped lateral was bilateral that had been reshaped with composite on the maxillary left side [ figure 1 ] . the tooth # 7 did not respond to thermal and electrical tests , and periodontal probing revealed normal periodontium . there was pain on palpation and severe tenderness to percussion without any mobility . the tooth # 7 was diagnosed as having a necrotic pulp associated with di type ii and acute apical periodontitis . the radiograph showed a mature lateral incisor with a sac shape invaginated portion limited to the root canal , which is diagnosed as di ( type ii oehlers ) . the radiograph also demonstrated an enamel - like radioopacity that appeared to be inside the main root canal system . an extended area of radiolucency adjacent to the root apex was noted [ figure 1 ] . ( a ) preoperative photograph : peg shape right maxillary lateral incisor and missing of the canine , ( b and c ) preoperative periapical and panoramic radiography : a mature lateral incisor with a sac shape invagination diagnosed as di ( type ii oehlers ) and an associated large periradicular lesion and missing of the right canine , and ( d ) peg shape left maxillary lateral incisor , which had been reshaped with composite veneer in the emergency appointment , needle aspiration was planned with # 18 g needle ( supa , tehran , iran ) to decompress the pressure and relieve the patient 's pain . the anterior palatal mucosa was anesthetized with incisive nerve block injection with 2% lidocaine with 1:80,000 epinephrine ( xylocaine , dentsply pharmaceutical , york , pa , usa ) . a clear yellow liquid ( 2 cc ) was aspirated and sent to the pathology laboratory . patient was subsequently informed about the complex anatomy of the tooth and the long - term prognosis of different treatment plans , and a decision was made to perform nsrct . the tooth was anesthetized with 2% lidocaine with 1:80,000 epinephrine ( xylocaine , dentsply pharmaceutical , york , pa , usa ) . for isolation purposes , the peg - shaped crown was first reconstructed by a composite resin ( solitaire 2 , heraeus kulzer , wehrheim , germany ) . access cavity was made from the lingual aspects with high - speed turbine ( super torque 625 ; kavo , joinville , santa catarina , brazil ) and diamond fissure bur ( dentsply , maillefer , baillaigues , switzerland ) . during access cavity preparation , it was tried to remove invaginated portion with fissure diamond bur # 0.8 ( dentsply , maillefer , baillaigues , switzerland ) under the use of operating surgical microscope ( global surgical , st . radiographs with two different horizontal angles were taken with gutta - percha placed in the drilled pathway to be sure about the direction of the bur drilling . after removing the sac - like portion , working length was determined radiographically with the association of an electronic apex locator ( rootzx , j morita , osaka , japan ) [ figure 2a ] . gates glidden drills and hand k - files ( dentsply , maillefer , usa ) were used to clean and shape canals . irrigation was performed with copious 0.5% naocl solution ( ims company , tehran , iran ) . calcium hydroxide ( pulpdent crop , watertown , ma , usa ) was placed in the canal for one week . the access cavity was sealed with temporary restoration ( cavit , 3 m , espe , seefeld , germany ) . ( a ) working length determination , ( b ) immediate postoperative periapical radiopraph taken after final canal obturation , and ( c ) 20-months follow - up radiograph demonstrating healing of periradicular lesion at the second appointment , the swelling disappeared . the tooth was anesthetized by buccal infiltration with 2% lidocaine with 1:80,000 epinephrine ( xylocaine , dentsply pharmaceutical , york , pa , usa ) . intracanal medicament was removed by 6% naocl irrigation for 5 min , and canal was made completely dried with paper points ( dentsply , maillefer , ok , usa ) . root canal was obturated with gutta - percha ( dentsply , maillefer , ok , usa ) and ah-26 sealer ( dentsply , detrey , konstanz , germany ) by injectable thermoplastic method [ figure 2b ] . the access cavity was restored with composite resin ( solitaire 2 , heraeus kulzer , wehrheim , germany ) . the 20-months follow - up clinical examination revealed healthy clinical appearance and function ; radiographs showed healing of periapical pathology . however , for complete healing of periradicular lesion more follow up is needed [ figure 2c ] . di always is an endodontic challenge for clinicians in both the diagnosis and the treatment stages . because of the frequent communication between the invagination and the oral cavity , the invagination makes the penetration of bacteria and their products into the pulp and periradicular tissue faster and easier and that increases the chances of pulp necrosis and periapical lesions . teeth with di can be asympthomatic and therefore not diagnosed even with large periapical radiolucencies , which leads to a more complex profile and more extensive bone loss . di treatments vary from simple preventive treatment like fissure sealant in early diagnosed cases to surgery and even extraction of the tooth , depending on the type and the degree of malformation . surgery may have been regarded as a suitable treatment in the past , but numerous studies have shown that nsrct can also be a successful alternative . shadmehr and farhad reported a large periapical lesion associated with di type iii in a canine tooth , which was completely healed by nsrct . because the tendency is to move toward more conservative treatments to avoid imposing unnecessary operative and radical medical procedures to the patient , it is often recommended to carry out surgery only if the nsrct has been attempted first and it has been unable to cure the problem . in the present case , the tooth appeared to be an oehler 's class ii with an invagination that remained confined within the root canal as a blind sac , with connection with the main root canal , which was treated successfully with nsrct . one of the difficulties and limitations of nsrct method that could lead to its unpredictable prognosis and its failure is the obstruction caused by invagination and the variability of complex internal anatomy of the root canal system limit the accessibility and makes it impossible to achieve complete debridement followed by its complete obturation with a biocompatible material . these varieties of canal morphology leave some regions of the canal unreachable . some authors have suggested strategies to overcome these issues . , holtzman and lezion , and shadmehr and farhad have assumed the invagination space and root canal space as two separate areas . holtzman and lezion treated his case by nsrct with calcium hydroxide , claiming to have cured the periapical lesion . however , he acknowledges that the space underneath the invagination area was inaccessible and was only filled by sealer . er et al . , used a triple antibiotic paste , a mixture of ciprofloxacin , metronidazole , and minocycline , which was described by takushige et al . , as an intracanal dressing as an alterantive to the use of calcium hydroxide and reported a complete healing . lichota et al . , have also treated di spaces separately , necessitating the need for a lubricant to prevent blockage of the file and reported successful nsrct even in di type iii with large periradicular lesion . in the present case , hard central invaginated part of the tooth was removed by fissure bur under surgical microscope , which provides better access for the clinician and in turn enables complete debridement and obturation to be achieved . girsch and mcclammy and silberman et al . , also recommended the removal of the central structure with the use of surgical microscope when the invagination tract and the main canal are separate entities . in the present case , it also helps the healing of periradicular lesion through increasing the ph of the periapical enviroment , providing calcium ion for repair process , and its denaturating effect on proinflammatory mediators such as interleukin-1 and tumour necrosis factor . use of ultrasonics for irrigation is another method that has been suggested to enhance disinfection process . some authors have used lateral or vertical gutta - percha obturation techniques or made use of mineral trioxide aggregate for obturation , but rotstein et al . , and nallapati recommended the use of thermoplastic technique , which was used in this case , as an effective method to obtain a sufficient seal at filling of such irregular canal spaces . it might appear that existence of periradicular lesion could interfere with nsrct , but most researchers state that the size of the periradicular lesion does not influence the method or the prognosis of the treatment . this case is another evidence that reports successful nsrct for a di tooth with assosiated large periradicular lesion . this case illustrated that a di type ii malformed tooth with a large periradicular lesion can be managed successfully with nsrct . furthermore , removing the hard central blind sac under surgical microscope provided better access for complete debridement . the use of calcium hydroxide paste as an intracanal medicament may provide an additional chemical debridement . utilization of thermoplastic technique for obturation may provide better adaptation to the complex internal morphology of invaginated canal .
dens invaginatus is a rare developmental anomaly of teeth with complex root canal system morphology . 
 the present case describes a peg shape maxillary lateral incisor with dens invaginatus ( oehlers type ii ) , necrotic pulp , and an associated large periradicular lesion . 
 nonsurgical endodontic treatment was performed with the aim of removing the blind sac with diamond bur under the use of operating surgical microscope . 
 the root canal system was obturated with thermoplastic technique . 
 final restoration was done using composite . 
 the 20-months clinical and radiological follow up revealed an asymptomatic tooth with healing of the periapical pathology ; however , for complete healed periradicular lesion more follow up is needed . 
 this case illustrated that a dens invaginatus malformed teeth with a large periradicular lesion can be managed successfully with nonsurgical root canal therapy ( nsrct ) .