Indications, clinical and laboratory stages of manufacture of pin teeth.

How ? Why ?

NON - ODONTOGENIC CYST CYST Misdiagnosis resulted in unnecessary endodontic treatment of four anterior teeth. 4/1972

Considerations for Anterior Teeth A metal post is not recommended in anterior teeth which do not require complete coverage restorations. This decision primarily focuses on: [1] the integrity of the remaining tooth structure. [2] the amount of functional load which to anterior teeth are subjected. [3] the morphologic development of anterior teeth.

Variation in bite force by location

The incisal edge of lower anterior teeth function across the lobes of opposing upper incisors

Comparative resistance to fracture to shear loading

Comparison of fracture stress with varying post types

Comparative fracture loads with and without posts

Considerations for posterior teeth Virtually all posterior teeth which have received endodontic therapy are in turn recommended for a cast restoration coronally. In turn if a coronal buildup is deemed necessary {core} for retention of the cast restoration, then further the decision for the need of a post must be determined. The prevailing considerations for posterior teeth: [1] greater functional loading of posterior teeth. [1] greater functional loading of posterior teeth. [2] morphologic disposition of posterior teeth to splitting. [2] morphologic disposition of posterior teeth to splitting.

Fusion of buccal and lingual lobes

Intra-radicular build up without post for molar teeth

Design Considerations for Posts

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Post - endodontic internal build up build up Direct restorative with or without prefabricated post in canal Custom cast post with core fabricated either directly or indirectly

Factors influencing retention of posts

Factors influencing resistance of posts

Design considerations for posts Diameter Diameter  retain as much dentin as possible in the roots of all teeth; increasing the diameter of the post has a minimally significant effect on the increase in retention.

Force in Kg Effect of Dowel Design and Diameter On Retention Zinc Phosphate 8 mm length

Design Considerations for Posts Taper vs. Parallel  parallel sided design has repeatedly been shown to create significantly less concentration of stress at its tip than a tapered design  parallel sided design has in various reports has been show to provide retention of 1.9 X, 3.3 X, 4.5 X greater than tapered design  in situations where a tapered design is used, it is critical to provide a flat root interface on which the core will seat

Force in Kg

Design Considerations for Posts Length Length  equal to the length of the clinical crown  equal to 3/4 of the root length  equal to 1/2 the length of the canal  equal to 1/2 the length of the root in bone  maintaining 4 mm. of endodontic filling material at the apex of the root

Design Considerations for Posts Length Length  equal to the length of the clinical crown  maintaining 4 mm. of endodontic filling material at the apex of the root

Design Considerations for Posts Surface Configuration  Fluted or irregular surface configurations because of their increased mechanical retention when cemented within the root are deemed most appropriate.  Adhesively bonded posts are not influenced by surface configuration. passive design”.  Active engagement of the root with threaded surface configurations have been shown to be the most retentive but also the most predictive of root fracture; therefore the recommendation for post placement into the root irrespective of surface configuration is a “passive design”.

Passive Active ABCD

Additional design considerations for posts Resistance form  the irregular shape of a canal particularly with a cast post/ core provides useful circumferential irregularity for an anti- rotational effect; in situations where this is not present and there is minimal remaining coronal dentin, it is advisable to prepare a keyway at the orifice of the canal or include supplemental pins for an anti- rotational effect.

Luting Materials for Posts Zinc phosphate Zinc phosphate - { Fleck’s, Tenacin } Glass Ionomer Glass Ionomer - { Fuji I, Fuji plus, Ketac-Cem } Polycarboxylate Polycarboxylate - { Livcarbo, Durelon, Hy-Bond } Adhesive resin Adhesive resin - { All- Bond, C& B Metabond, Variolink II, Panavia }

Effect of luting agent on retention

Manipulation of cement during post placement

Additional Design Considerations with Posts Ferrule effect The principle of extending the crown margin apical to the ‘tooth stump - core interface’ at least 1.5 mm. to circumferentially encompass the tooth. This reduces the fracture potential of the post within the root when the crown is in function.

Fracture Comparison of Post Designs with and without Ferrule

Fracture comparison of post designs with and without ferrule

Customized Cast Post and Core  Direct pattern fabrication  Indirect pattern fabrication

Materials/Designs/Shapes Material Fiber reinforced Zirconium Stainless steel Titanium Design Active Passive HybridShape Parallel Tapered Multi-stage

Fiber reinforced Enhanced aesthetics Excellent biocompatibility No galvanic corrosion signs Mechanical properties similar to dentin Easy to use and remove Firm retention - adhesive bonding Lower radiopacity than metal post

Stainless Steel Good mechanical properties Problematic esthetics at times Potential corrosion and embedding of decomposition products Potential damage to remaining structure Cemented using zinc phosphate, glass ionomer, or polycarboxylate cement.

Titanium Good mechanical properties Excellent biocompatibility Questionable aesthetics at times Potential damage to remaining structure Cemented with zinc phosphate, glass ionomer,or polycarboxylate cement

Metal v. Fiber Reinforced Metal Coronal impact is transmitted to remaining tooth Fiber reinforced Coronal impact is dispersed through the post alleviating force on remaining tooth

Active Threads to engage the dentin Provides the greatest retention method Risk that engagement may lead to fractures Material is metal

Passive Smaller diameter than drill diameter No risk of engaging dentinal walls Slightly more material must be removed than metal post Adhesive bonding increases retention

Hybrid Active at coronal end and passive at apical area Used where some mechanical retention is demanded Material is always metal Active Passive

Parallel Same width from coronal to apical area Greater retention /given length Requires removal of more tooth structure at apical end of post than tapered design

Tapered Narrower at apical than coronal area Designed to adapt to constriction of root dentin Requires less dentin removal in apical extent

Multi Stage Mainly made in metal designs Larger at coronal area and narrower at apical area More technique sensitive Requires multiple drills

Fiber Reinforced Posts

Titanium Posts

FRC Postec System

FeaturesBenefits Metal-free post with a high degree of translucency Esthetic properties compatible with all-ceramic restorations Longitudinal placed glass fibersProvides light transmittance & translucency Modulus of elasticity similar to dentinMinimizes stress concentrations within root structure ? Passive, tapered designProvides an excellent fit and saves remaining tooth structure at apical extent ? Two post sizes with color coded matching reamers Applied to virtually all teeth except those with extremely small diameter roots Adhesively bondedExcellent retention properties Integrated systemCoordinated materials for a total adhesive build-up technique RetrievablePossibility for endodontic re-treatment

Radiopacity FRC Postec shows reduced radiopacity Used in conjunction with Variolink II provides additional x-ray identification

Comparative X-rays FRC Postec ParaPost Fiber White FiberKor Luscent Anchor Ivoclar Vivadent Coltene Whaledent Pentron Dentatus

Removal FRC Postec can be removed with a rotary instrument if retreatment is required

Post space preparation Is it necessary ? Which canal(s) ? What size and length ? What material ?

Post Space Preparation 4 mm Length of Clinical Crown

Conditioning of the Post Space Try in the post Rinse the canal With NaOCl or H 2 O 2 Dry canal with paper points

Conditioning of the Post Space 15s Etch canal and coronal dentin with phosphoric acid Rinse all residue of etching gel Dry canal with paper points

Conditioning of the Post Space 10s Apply dual cure bonding agent Remove excess With paper points Rinse post with alcohol and dry

Conditioning of the Post Coat the cement on FRC Postec Mix Variolink II Base and Catalyst Place the post and fully seat it Remove excess

Conditioning of the Post 60s Condition post surface 60 sec with silane Air dry post Dispense luting resin

Coating and placement of the Post Mix equal lengths of base and catalyst for 20 sec Coat the post with resin cement Passively seat the post and remove excess above canal orifice

Direct Core Build-up 40s60s Light cure for 60 sec Build up core with direct composite in increments Prepare tooth for crown