Mechanical principles of tooth extraction
Applying displacing force: direct and indirect (forceps and elevator) Expansion of socket by lateral displacing movement (forceps ) Use of lever and fulcrum (elevator) (line of withdrawal) Insertion of a wedge between the root and bony socket (elevator or forceps) Bone removal using bur or chisel Tooth sectioningMethods of tooth extraction
Closed (intra-alveolar) extraction Open ( trans-alveolar ) extractionForces of extraction
Force should be firm, smooth and controlled to separate gingival attachment, cutting periodontal ligament and expanding boneApical pressure Buccal force lingual force Rotational force ( 1ry & 2ry ) Parallel occlusal force
Procedure for closed
extractionSteps
1-Gum separation objectives? 2-Luxation of tooth by elevator 3-Adaptation of forceps 4-Luxation of tooth by forceps 5-Removal of the toothImportant notes
1-The forceps need to be seated apically as far as possible & reseated periodically. 2-The buc-ling force applied by forceps should be slow , under control & not jerky. 3-The force should be held for several seconds to allow bone to be expand.Upper central incisors: Primary rotational movement. Upper lateral incisors: Fine bladed forceps, labio-palatal movement. Upper canine: Long strong root with a nearly triangular cross section. Great force needed. Fracture of the labial cortical plate may occur. Movement is labio-palatal.
Extraction Specifics
Maxillary 4 : Birooted, remove in the direction of least resistance. It is better for this tooth to be pulled out but in practice slight lateral movement is often required to deliver the tooth. Rotational forces for this tooth are contraindicated. Maxillary 5 : Buccal bone thinner, this tooth yields to lateral movement buccally and then secondary rotational movement is made followed by pulling tooth occlusally in the buccal direction.
Maxillary 6 : The palatal root is usually straight; the mesio-buccal root apex has a severe distal curvature, By careful rocking of the tooth buccally, the palatal root may become loose and by a complete bucco-lingual movement will complete luxation. This tooth is removed without secondary rotational movements. Maxillary 7 : Buccal alveolar plate offers least resistance, roots are straight and close together and may be fused, If this tooth is fractured, difficult to be removed.
Maxillary 8 : Crown placed more posterior than its roots, difficult application of forceps ,if mouth opened widely, coronoid process interferes with access and increase difficulty. Partial closure of the mouth with the mandible deviated towards the extraction will aid in achieving access. Root is tilted backwards distally.
Mandibular incisors: Fine mesial and distal surfaces, apex curved distally, narrow bladed forceps are used to grasp them without trauma to the neighboring teeth, luxated labially. Mandibular canine: Long and bulky, firmly embedded and in cross section it is nearly triangular in shape, luxate it lingually.
Mandibular 1st premolars: Tooth yields to buccal pressure with slight mesiodistal rotation. Mandibular 2nd premolars: Straight and conical , initial rotary movement can luxate the tooth changed to lateral bucco-lingual movement
Lower 1st molars: Fracture during tooth extraction? The roots are wide and flat in the mesial and distal surfaces, great resistance ; loosened by buccolingual pressure and are best delivered by a figure eight secondary rotation Lower 2nd molars: More easier than lower 1st molars? smaller , straight tapering and less divergent roots ;may be fused; use bucco-lingual pressure; removal is made in a buccal and upward direction
Mandibular 3rd molars: Careful radiograph indicated ? The roots of this tooth may be short, long , fused , multiple , diverged , curved or straight . The alveolar bone is extremely thick especially in the buccal side of the tooth where the external oblique ridge may project and so a lingual movement of forceps is dominated and in most cases an elevation is required.