classification and impression techniques of implants
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Classification and impression techniques of implantsBy Dr.K.V.Anitha(PG Student) Student)
ClassificationBased upon1. 2. 3. 4. 5. 6. 7. 8.
Placement within the tissues Materials used Attachment mechanism Surface coating Shape Surgical stage Mode of insertion Tissue response & systemic toxicity effects of implants
Based upon the placement within the tissueSubperiosteal implants
Subdivision of subperiosteal implanto o o o
Unilateral Interdental Total circumferential
Unilateral subperiosteal implant
Interdental subperiosteal implant
Total subperiosteal implant
Circumferential subperiosteal implant
Transosteal implant Also known aso o o
Staple bone Mandibular staple Transmandibular
Endodontic stabilizer implant
Based upon materials used1.Metallic implants-commercially pure titanium implantsTitanium alloy Cobalt chromium molybdenum alloy 2.Nonmetallic implants-Ceramics implantsCarbon
Ceramic and titanium alloy implants
Based upon the attachment mechanism1.Osseointegration 2.Fibro osseous integration
Based upon their surface coatingo o o o o o
Titanium plasma sprayed Hydroxyapatite coating Grid blasting with TiO SLA(sandblasted-largegridSLA(sandblasted-largegrid-acidetched) Acid etched Machined surface
Based upon the shape
Contd .o o o o o
Threaded,nonthreaded Tapered,parallel With vent holes,without vent holes Hollow cylinder,solid screws Root form,blade form
Based upon the surgical stageTwo stage implants One stage implant
Based upon mode of insertion
1.Axially inserted (crestal approach)
2.Laterally inserted(basal approach)
Based upon tissue response &systemic toxicity effects of implantso
Biotolerant materials-polmethylmethacrylate materialsBioinert materials-titanium and aluminium materialsoxide Bioactive materials-glass and calcium materialsphosphate ceramic
Components of implant
IMPRESSION MATERIALS Ideal RequirementsComplete plasticity before cure Fluidity to record fine detail Ability to wet oral tissues Dimensional accuracy Dimensional stability Complete elasticity after cure Optimal stiffness
o Alginate o Agar o Polysulphide o Polyether o Condensation Silicone o Addition Silicone
o Poor dimensional stability o Poor dimensional accuracy o Poor tear strength o Poor stiffness o Interferes with setting of gypsum
AGARo Interferes with setting of gypsum o Dimensional instability o Elaborate equipment needed o Low tear resistance
o Base-polusulfide polymer, Catalyst- lead dioxide o High tear strength o Messy,unpleasant odour o Long setting time o Poor dimensional stability o Hydrophobic
o Cheaper o Good tear strength, accuracy & elastic properties o Dimensional instability,due to loss of ethyl alcohol o Poured quickly
o Shorter setting time o Easy to mix- automatic mixing devices o Adequate tear strength o Extremely high accuracy o Dimensional stability even after 1 week o Least distortion on removal o Hydrophilic o Good compatibility with gypsum
o Good dimensional stability & accuracy o Short setting time o Material very rigid o Not available in all consistencies o Most expensive
Dispensed as :
o Putty o Heavy body o Monophase o Light body
Automixing equipment & materials
Two basic impression techniques for implants are
1. indirect technique or closed tray technique 2.direct or pick-up or open tray technique.
Indirect impression technique
Direct impression technique
Related articlesTautin(1985)presented a technique to accurately, transfer and reproduce the relationship between implant dentures , in which no preliminary impression or acrylic resin custom tray were needed. He used modeling compound to form a custom tray by adapting it over transfer copings,pressing the compound over the superior aspect of the coping so that its circular outline is seen through the compound.After trimming the outline of the coping showing through the top of the tray an impression plaster is used to record and transfer the coping to the impressions
Loos(1986)presented a detail technique for the
fabrication of a fixed prosthesis supported by implants.His technique incorporated plugging the incisal end of the transfer coping with beading wax(to prevent impression material from flowing into it)splinting the transfer copings with orthodontic ligature wire and Duralay acrylic resin,use of a plastic perforated impression tray with incisal window to access the transfer coping and making the final impression with putty light body addition silicone.
Rasmussen(1987)presented a technique in which the existing denture is modified using tissue conditioning material is used instead of healing caps after second stage surgery ,eliminating the use of impression copings at the final impression.
Humphries et al (1990) evaluated the accuracy of implant master casts constructed from transfer impressions using three techniques.The techniques used were splinted square polymer copings,unsplinted square polymer copings and unsplinted hydrocolloid copings.Tapered hydrocolloid copings were more accurate than the other two methods.
Carr (1991) compared impression techniques for five implant mandibular model by both indirect and direct transfer coping techniques and found that for the models used ,the direct method produced more accurate working casts.
Vigolo et al(2000)evaluated the accuracy in transferring the position of the hexagonal head of a single implant to the working cast, and concluded that the sandblasting and coating the roughened surface of the impression coping with an impression adhesive will result in more accurate orientation of the implant replicas in the laboratory master casts in single tooth implant restorations.
ConclusionSuccess with implant prosthodontics requires a careful attention to each and every step from diagnosis and treatment planning. Several implant systems are available , selection of appropriate one is mandatory. The prosthesis fit can be accurate only if a proper impression is made. Thus usage of correct impression technique and material are important.
References1. contemporary implant dentistry , Carl E. Misch 2. Implants in dentistry , Michael,John and Luis. 3. Implant prosthodontics Stevens & freidrickson 4. Dental implants- Fundamental & advanced laboratory technology , Robert Winkleman &Kenneth orth.
References contd5. Philip s science of dental materials 6. Contemporary fixed prosthodontics, Rosentiel 7. Principles & practice of implant dentistry, Weiss 8. Theory & practice of ossteointegration, Hobo 9. Carr AB. Int J Oral Maxillofac Implants. 1991;6(4):448-55 10. Assif etal. Int J Oral Maxillofac Implants. 1999;14(6):88588 11. Loos Larry G. J Prosthet Dent 1986;55:232-42 12. Rasmussen Eric J. J Prosthet Dent. 1987;57:198-203 13. Tautin Francis S. J Prosthet Dent. 1985;54:250-51 14. Vigolo etal. J Proshtet Dent. 2000;83:562-66