Characteristics Of The Anatomical Structures Observed On Cone Beam Computed Tomography Images In The Mandibular Interforminal Region And The Case Report Of Implant Restoration Treatment In The Mandibular Anterior

ObjectiveTo investigate by means of Cone Beam Computed Tomograghy (CBCT) thepresence and length of the anterior loop (ALL), the visibility and course of themandibular incisive canal (MIC), the visibility and location of the Mandibular lingualforamen (MIF) and the course of its bony canal in the interforaminal region. Accordingto the statistic data and image information, this study may be used to providerecommendations to the surgeon about a new safety margin in the interforaminal regionespecially without access to CBCT.Materials and methodsThe fifty-two patients (48dentulous ones, male25, female23; average age40.9,age from18to68;3edentulous patients, male3, female1, average age65, age from56 to72) scanned with KaVo3D CBCT are obtained from Dalian Stomotological Hospitalaffiliated to Dalian Medical University, from July2013to January2014. The imagereconstruction from the raw data was performed using the Examvision software. Twoprofessional dentists were asked to (1) investigate the presence of the anterior loop, themandibular incisive canal, the mandibular foramen and its bony canal fromreconstructed images;(2)Measure the anterior loop length and three dimensionaldiameters of the mandibular incisive canal and the distance from the incisive canal tothe tooth apex, buccal and lingual plate, the upper and lower mandibular border;(3)detect the lingual foramen of its diameter in the lingual border, distance from upper andlower cortex; trajectory of the foramen and its corresponding vascular canal.Result(1) the anterior loop, the incisive canal, the lingual foramen and its canal werevisible in56.7%(57.7%right,55.8%left),100%,92.3%of the scans, respectively.(2)the mean anterior loop length was1.10mm(1.14right,1.07left;1.33male,0.84female),no significant differences between the anterior loop length on the basis of both sides andpatient sex.(3) the distances from the incisive canal to the tooth apex, buccal andlingual plate, the upper and lower mandibular border were3.5m、5.36mm、8.00mm、18.5mm and9.85mm of the scans respectively; the mean diameters of the incisive canalof its dimensions were2.47mm and2.33mm(length, width).(3) the average diameter ofthe lingual foramen was1.76mm, and the average distance from the foramen to theupper and lower of the mandible border were16.87mm,12.83mm respectively;37.5%of the vascular canals penetrated the lingual third of the width,58.3%reached themiddle third of the mandible and only4.2%of the canals spread to the buccal third.ConclusionBecause large variations in measurements were observed, either for ALL, MIC orMIF, no fixed distance from these anatomical structures should be considered safeabsolutely. Since the preoperative CBCT images and its measurements yield significantinformation for each case we recommend the use of the CBCT scans for implantplanning or bone harvest surgery in the interforaminal region. In the absence of the CBCT scans, the new relative safety margins should be a distance of at least6mmbetween the anterior border of the mental foramen and the most distal interforaminalimplant fixture or bone harvest site; the maximum bone harvest depth is suggested to be3mm and implants length should be less than14mm in the placement of the anteriormandible implant.