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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

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Tittle “ Safe Zones” : A guide for miniscrew positioning in the maxillary & mandibular arch • P. M Poggio • C. Incorvati • S. Velo • Aldo Carano AO 2006;76:191-197 www.indiandentalacademy.com


AIM • ‘ To provide an anatomical map to assist the clinician in mini screw placement in a safe location b/w dental roots of the post teeth ‘ • To identify the morphological features of the ideal miniscrew

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Review of literature • Mini screws –as an alternative method for absolute orthodontic anchorage / TAD • History -1969 Linkow • Hyo-sang Parkkorea,popularised www.indiandentalacademy.com


• Numerous anatomical sites for the mini screw placement have been presented • Kanomi & cost et al – placed in the basal bone below the roots-to prevent root damage As screws placed high-applied force was limited • Park et al- placed in the alveo bone b/w post teeth to H/Z force www.indiandentalacademy.com


• Critical issue ? anatomical guide lines for safe insertion • A single study-Park HS Anatomical study using CT images for the implantation of MI (kor J ortho1999) • >amount of bone in Maxi-5 & 6 Mandi- 6 & 7 www.indiandentalacademy.com


MINI SCREWS • Small,simple & nonosseointegrating • Available in 6,9,12mm length • 1.2-1.5mm dia (1.2mm-best)

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Applications:  Reinforce anchorage / sole source of anchorage Tooth movements  Intrusion / extrusion  Molar uprighting & distalization  Retraction (single / en masse)  Correction of AOB,Crossbite  Close edentulous spaces  Orthopedic movements-sutural distraction (palatal expansion) www.indiandentalacademy.com


• Mini screws as an IO anchorage has proved more advantages over EO  Small simple comfortable to pt  No interference  Placed in many IO areas  Comparatively less cost  Easy implantation & removal www.indiandentalacademy.com


Materials & Methods DATA: • Digital vol tomography new tom (DVT9000) • 2000 pts-20-40yrs • CT images-25 Max & 25 Mandi • Exclusion-crowding,missing,PDL diseases www.indiandentalacademy.com


Measurements: For each interradicular space • M-D & BL distance • At diff depth from alveo crest- 2,5,8 & 11mm

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M-D measurements: • Post region-2 reference planespalatal & buccal side

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• Ant region-single refernce plane

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B-L measurements: • Intr radicular spaces at- 2,5,8 & 11mm • Total 144 measrues -25 maxill 104 measrues -25 mandi • Method error(ME)-dahlberg formula both MD&BL measurements-not statically significant www.indiandentalacademy.com


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Results

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Discussion : • Aim-analyze the interradicular spaces • Most scews 1.2-2mm dia • No data to know how much bone is necessary b/w screws & dental roots for PDL health & screw stability www.indiandentalacademy.com


Safe zones

Green : MD >3.1mm –for placing maxi dia 1.2-1.3mm 1.5mm screw-safe if 3.5mm of space Blue : MD b/w 2.9-3.1mm

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Note: • Placed at 30-40 to long axis of tooth • Maxi molar area-avoid above 8-11mm  Maxi sinus  Tuberosity – less bone wisdom teeth • Palatal region is safe than buccal as more M-D bone

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Conclusion SAFE ZONES : Maxilla: (more ant & more apical-safer)  6-5  7-6  5-4  4-3  6-5

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palatal side (2-8mm level) palatal side (2-5mm level) buccal / palatal (5-11mm) buccal / palatal (5-11mm) buccal side (5-8mm) www.indiandentalacademy.com


MANDIBLE:    

7-6 5-4 6-5 4-3

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• All findings – from nontreated pts • Act as a guide – but need for a radiographic evaluation before implantation • For orthodontic anchorage-the ideal mini screw should be -1.2-1.5mm dia,6-8mm length & conical shape

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Thank you For more details please visit www.indiandentalacademy.com

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