trauma accompanied by fracture of anterior teeth is an unpleasant experience for the patient who requires attention not only because of damage to the dentition , but also due to the psychologic effect of trauma .
the majority of dental injuries involve the anterior teeth , especially the maxillary central incisors .
a number of techniques have been reported in literature for rehabilitation of grossly mutilated teeth.[28 ] the aesthetic rehabilitation of patients with mutilated teeth generally involves a multidisciplinary approach .
however , during the restorative procedures , negligence of periodontal tissues is of common occurrence , and is often the cause of failure .
hence , it is essential to maintain a healthy periodontium and the biologic width while restoring teeth . the damaging effect on the periodontium of restorations with subgingivally placed margins is an important factor that needs to be considered during restorative treatments .
crown lengthening can be performed by using various methods , and , orthodontic extrusion is regarded as the best method for lengthening of the clinical crown length .
orthodontic extrusion has been referred to as  slow eruption of teeth ,  which indicates that by utilizing light eruptive forces , the entire attachment apparatus can be shifted coronally in unison with the tooth .
the main advantage of the orthodontic extrusion is that the root can be kept within the alveolus , thus the bone height is maintained without compromising the periodontal support .
endodontically treated teeth with insufficient tooth structure are often restored with crowns . if there is insufficient dentin to support a restoration , a post - core is required to provide retention and support .
the choice of an appropriate restoration for endodontically treated anterior teeth is guided by strength and esthetics .
the cast gold post and core has been considered the gold standard because of its excellent success rate , favorable long - term prognosis , and ease of fabrication . traditionally , titanium , carbon , polyethylene fiber , and stainless steel posts have been used for the anterior region . however , when all - ceramic restorations are preferred , metal posts may negatively affect the esthetic results .
with regard to both esthetic and health concerns , non - metal posts not only render esthetic superiority over metallic posts , but also preclude the possibility of corrosion and reduce the risk of toxicity .
use of zirconia as a post - and - core material began in 1993 when introduced by meyenberg et al .
the technique for milling a 1-piece zirconia post and core has been described by awad and marghalani and streacker and geissberger .
computer - aided design and computer - aided manufacturing ( cad / cam ) milled zirconia posts and cores can be used when esthetic demands are important , and when the anatomy of the root canal and/or the extensive loss of the coronal tooth portion requires the use of a custom post .
this technique also allows the possibility of completing a post and core in the same appointment .
as stated in various reports , this technique provides a post and core with greater toughness , maximal adaptability to the canal , and adequate esthetics . here
, we report a case of aesthetic rehabilitation of grossly destructed maxillary right central incisor using a multidisciplinary approach i.e. conventional endodontic treatment followed by orthodontic extrusion , and final restoration using cad - cam fabricated one piece milled zirconia post and core with full coverage zirconia crown .
a 22 year old male reported to department of conservative dentistry and endodontics with the chief complaint of fractured maxillary right central incisor due to trauma 5 years back [ figure 1a ] . on clinical examination , a grossly destroyed carious crown with minimal remaining dentin was present with tooth # 8 [ figure 1b ] .
preoperative intraoral periapical radiographs showed gross destruction of crown of # 8 with wide canal and periapical radiolucency and deep proximal caries with # 9 [ figure 1c ] .
pulp vitality tests ( electric and cold tests ) revealed that tooth # 9 was non vital .
hence it was decided to restore the tooth with conventional endodontic treatment and post and core restoration .
after excavation of caries it was seen that supragingival crown height both labially and palatally was 0.5- 1 mm . the crown :
root ratio and occlusal clearance was adequate . hence in order to gain crown height for fabrication of a customized post and core with full coverage crown , it was decided to treat the tooth by forced orthodontic extrusion .
the tooth was isolated under rubber dam ( hygienic dental dam , coltne whaledent , germany ) .
adequate endodontic access cavity was prepared after excavation of caries and working length radiograph was taken after initial identification of canal with # 15 k - files ( kerr manufacturing co. , romulus , mi ) . cleaning and shaping of the root canal was performed by using stainless steel file with a crown - down technique under copious irrigation with saline , 5.25% sodium hypochlorite solution ( dentpro , chandigarh , india ) and 17% ethylenediaminetetraacetic acid ( edta ) ( glyde file prep , densply , france ) . in the next visit master cone
the canal was finally rinsed with saline , dried and sectional obturation was performed using cold lateral compaction of gutta - percha using ah plus resin sealer ( maillefer , dentsply , konstanz , germany ) [ figure 1d ] .
an irm ( caulk , dentsply , milford , de ) temporary restoration was placed in the access cavity .
( c ) : preoperative diagnostic radiograph showing gross destruction of crown of # 8 with wide canal and periapical radiolucency and deep proximal caries with # 9 .
a lingual button was cemented on the tooth # 8 , and 18 slot preadjusted brackets were cemented on teeth # 6 , 7 , 9 and 10 for controlled extrusion .
an auxiliary 0.014 superelastic niti wire was overlaid on the stainless steel wire [ figures 2a and 2c ] .
a force of 40 - 50 gram was applied and extrusion was achieved after 4 weeks .
the final crown height obtained labially and palatally was approximately 3 mm which was adequate for a crown ferrule and retention of the prosthesis [ figures 2b and 2d ] .
after active tooth movement was complete , the tooth was stabilized with fiber splints ( polydentia , mezzovico , switzerland ) for a period of 4 weeks for reorganization of periodontal tissues before fabrication of post and core [ figure 3a ] .
( d ) radiograph showing orthodontic extrusion of maxillary right central incisor after four weeks of orthodontic treatment .
( b ) radiograph of the prepared post space in the root canal of the maxillary right central incisor of the patient .
( c ) and ( d ) direct impression of post and core by using pattern resin . at the following appointment ,
the root canal anatomy of maxillary right central incisor did not permit use of a conventional prefabricated glass fiber post , as the post diameter would not have allowed for good adaptation to the post space , and the resulting thick cement layer would have affected the bond strength , increasing the risk of mastication induced fracture [ figure 3b ] . a cast gold post and core would have been the method of choice for this situation , but the metal color would have affected the translucency of a subsequent ceramic restoration . keeping the above factors in mind , cad / cam fabricated zirconia post and core and a ceramic crown
were planned to restore the tooth . to gain adequate length for the post space ,
a portion of gutta - percha was removed with heated hand plugger ( kerr manufacturing co. , romulus , mi ) , such that the remaining gutta - percha at the apical portion was 5 mm [ figure 3b ] .
the post space was prepared using peeso reamer number three and four ( dentsply maillefer , ballaigues , switzerland ) to eliminate undercuts , because it was already relatively wide .
a direct impression of the post space was made using pattern resin ( gc america inc , alsip , il ) [ figure 3c ] .
after impression of post space , core was also build up with pattern resin [ figures 3d and 4a ] .
an impression of the post space and adjacent teeth was made using hydrophilic addition silicone impression material ( dentsply caulk , milford , usa ) which was cast in type iv high - strength die stone ( royal rock ; pemaco , inc , st .
the direct resin pattern was digitized with a 3-dimensional ( 3-d ) scanner ( amann girrbach gmbh , pforzheim , germany ) and the data were processed using cad / cam software [ figure 4c ] . a digital 3-d model of the post and core was developed .
a prefabricated zirconia block ( amann girrbach gmbh , pforzheim , germany ) was milled to develop the post and core [ figure 4d ] with a milling machine ( amann girrbach gmbh , pforzheim , germany ) .
the milled ceramill zirconiumoxide frameworks were dense - sintered with the ceramill therm to obtain their final density and excellent material properties . the zirconia post and core
was then wrapped with red , 8-m thick articulating paper and placed into the post space of cast to evaluate fit .
after removal , interferences were relieved using a finishing diamond rotary cutting instrument in a high - speed handpiece ( nsk , nakanishi inc , kamura , japan ) .
post surface was air - abraded with 50-m aluminium oxide ( al2o3 ) particles prior to cementation .
the cementation procedure was then performed using a dual - cured resin cement ( variolink ii , ivoclar vivadent ) according to manufacturer 's instructions .
( b ) indirect impression of the post space and adjacent teeth using hydrophilic addition silicone impression material .
( c ) use of computer - aided design and computer - aided manufacturing ( cad / cam ) for data processing .
. the temporary restoration was removed , and dentin was cleaned and conditioned with 37 c phosphoric acid for 15 seconds .
this was followed by applying a dentinal adhesive ( syntac adhesive , ivoclar vivadent ) for 10 seconds and then dried .
both the base and catalyst of the resin cement were then mixed and applied on the post surface as well as post space .
after inserting the post into the canal , excess cement was removed , and polymerization was initiated using a polymerization lamp for 40 seconds [ figures 5a , b and c ] .
intraoral view of the cemented zirconia post and core ( a ) facial view ( b ) occlusal view .
zirconia - based crown was fabricated by the same procedure as post and core [ figures 5d , e and 6a ] .
after the final zirconia crown [ figure 6b ] was seated over the tooth , marginal fit was examined using a dental explorer .
the cementation procedure for the crown was performed using the adhesive technique similar to that for the zirconia post [ figure 6c ] .
a periapical radiograph demonstrated that post and core remained well adapted to post space and there was a complete healing of periapical lesion [ figure 6d ] .
( a ) computer - aided design and computer - aided manufacturing ( cad / cam ) view of zirconia coping .
( d ) radiograph of the maxillary right central incisor after 3 months of therapy demonstrating post and core in a well maintained condition and complete healing of periapical lesion .
while placing a restoration it is important to maintain the biological width to avoid periodontal problems and ultimate failure of the restoration . in a healthy individual this width
inber js was the first to suggest the use of forced eruption to treat non restorable or hopeless teeth .
forced eruption allow the crown margins to be placed on the sound tooth structure while maintaining a uniform gingival contour that provides improved aesthetics without involving adjacent teeth .
it also maintains acceptable crown - root ratio , biological width and good periodontal health .
forced eruption is an excellent alternative to traditional surgical crown lengthening and surgical extrusion especially , in the anterior region of the mouth .
surgical crown lengthening is contraindicated on aesthetic grounds and involves chances of violation of biological width compromising periodontal health .
surgical extrusion also is a questionable tool , requires 4 - 6 months of healing period and the procedure is technique sensitive .
the major limitation of forced eruption is the longer duration of treatment and a longer stabilization period ( 4 - 8 weeks ) .
it is also contraindicated in an inadequate crown to root ratio , lack of occlusal clearance for required amount of eruption and periodontal complications .
remaining tooth structure and tooth morphology , functional demands , arch position , periodontal status , and esthetics are few of these factors .
various post systems are available ; however , 1-piece milled zirconia posts and cores can be used when esthetic demands are important and when the anatomy of the root canal and/or the extensive loss of the coronal tooth portion requires the use of a custom post . when restoring a severely damaged clinical crown with a wide post space ,
the 1-piece zirconia post and core can be well adapted and the cement layer thickness thus can be reduced .
the modulus of elasticity of the 1-piece glass fiber post and core is similar to that of dentin , which limits stress concentration in the weakened root canal .
the cad / cam systems offer advantage of automation of fabrication procedures with increased quality in shorter period of time .
the primary disadvantages of cad / cam fabricated zirconia post and core are its relatively complex production process and high cost .
this case report highlights the use of forced orthodontic extrusion and cad / cam milled zirconia post for rehabilitation of grossly destructed crown .
forced orthodontic extrusion was selected as it maintains acceptable crown - root ratio , biological width , good periodontal health and aesthetic demand .
other procedures like surgical crown lengthening and osteotomy have compromised aesthetic demand , inverse crown - root ratio , compromised function of adjacent teeth and the biological width maybe hampered .
cad / cam milled zirconia post and core was selected because of the wide canal in this case with severe coronal destruction , and also as the use of zirconia post and core with all ceramic crowns optimizes the esthetic effect of the restoration .
this clinical report describes a method of utilization of forced orthodontic eruption as an alternative to periodontal surgery , and a method for restoring a fractured anterior tooth with a 1-piece zirconia post and core milled with cad / cam technology . using this method , a precise fit of post and core
this technique can provide a complete aesthetic rehabilitation of grossly destructed tooth without hampering the biological width , and thus has a better prognosis .
as cad / cam and zirconia technology are relatively new eras of dentistry , they might undergo evolutionary changes in near future .
 the aim of this study is to present a report of a case where forced orthodontic extrusion and computer - aided design and computer - aided manufacturing ( cad / cam ) technique was used for reconstruction of right maxillary central incisor with grossly destructed crown . 
 aesthetic rehabilitation of a fractured maxillary right central incisor was performed employing a multidisciplinary approach i.e. conventional endodontic treatment followed by orthodontic extrusion and final restoration using cad - cam and one piece milled zirconia post and core with full coverage zirconia crown . 
 after the procedure being completed , periapical radiographs taken at 3 month follow up period demonstrated that the post and core remained well adapted to post space and there was a complete healing of periapical lesion . 
 this technique can provide a complete aesthetic rehabilitation of a grossly destructed tooth without hampering the biological width and thus has a better prognosis . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSIONS