IMPLANTS

Implants

1. IMPLANTS : BASIC CONCEPTS

2. CONTENTS :  Implant introduction  Implant classification  Implant geometry ( Macro design) ◦ Endosseous implants ◦ Subperiosteal implants ◦ Trans mandibular implants  Implant surface characteristics ( micro design) ◦ Additive processes ◦ Subtractive processes  Hard tissue interface ◦ Stages of bone healing and osseointegration  Soft tissue interface

3. INTRODUCTION : Implant :- Any object or material , such as an alloplastic substance or other tissue, which is partially or completely inserted or grafted into the body for therapeutic , diagnostic, prosthetic or experimental purposes.  Dental implant :- A prosthetic device of alloplastic material Implanted into the oral the oral tissues beneath the mucosa, periosteal layer and or within the bone to provide retention and support for a removal or fixed prosthesis .

4. Implantology :- The study or science of placing and restoring dental implants. Implant surgery :- The phase of implant dentistry concerning the selection, planning, and placement of the implant body and abutment. Implant prosthodontics :- The phase of prosthodontics concerning the replacement of missing teeth and/or associated structures by restorations that are attached to dental implants

5. TERMINOLOGIES: Following are the terminologies related to implants : Body : The body is that portion of the implant designed to be surgically placed into the bone . Cover screw : In two-stage implant, the first-stage cover screw is positioned on the top of the implant .

6. Healing abutment/per mucosal extension : In two-stage implant, a second surgical procedure is conducted to expose implant and provide attachment to a transepithelial portion. This transepithelial portion is called per mucosal extension . Abutment: The abutment is the implant’s part that help to support and/or retain the prosthesis or implant superstructure in position .

7. INDICATIONS : ‰ Edentulous patient: One of the first indications for dental implant treatment is to treat complete edentulism. ‰ Partially edentulous patient . ‰ Single tooth loss: Implant maintains bone volume after tooth extraction. ‰ Anchorage for the maxillofacial prosthesis: Patients with maxillofacial deformities uses implant for the maxillofacial prosthesis.

8. ‰ For rehabilitation of congenital and developmental defects like cleft palate, ectodermal dysplasia, etc. ‰ For orthodontic anchorage .

9. CONTRAINDICATIONS : ‰ Immunologically compromised patients: Systemic diseases such as developing cancer and AIDS. ‰ Cardiac diseases : Implant surgery should be carefully considered in patients with heart valve replacements and should not be performed on patients having suffered from recent infarcts, i.e. within the latest 6 months period. ‰ Deficient hemostasis and blood dyscrasias .

10. ‰ Certain psychiatric disorders: Patients with psychological disorders have difficulties in cooperating and maintaining sufficient oral hygiene . ‰ Uncontrolled acute infections, as in the respiratory tract, may negatively influence the surgical procedure or may affect the treatment result and are thus, a contraindication for surgical treatment . ‰ Anticoagulant medications

11. ‰ Recent history of orofacial irradiation: Irradiation of the jaw may be another potential risk factor for implant treatment, specifically if the jaw has been exposed to irradiation over the level of 50 Gy. ‰ Heavy smoking and alcohol abuse. ‰ Various intraoral contraindications are : Xerostomia Macroglossia Unfavorable intermaxillary occlusal relationship.

12. CLASSIFICATIONS: BASED ON IMPLANT DESIGN BASED ON ATTACHMENT MECHANISM BASED ON MACROSCOPIC BODY DESIGN BASED ON SURFACE OF THE IMPLANT BASED ON TYPE OF MATERIAL

13. Based on implant design :

14. Implants geometry (macro design)  Endosseous implants ◦ blade like ◦ Pins ◦ Cylindrical (hollow and solid) ◦ Disklike ◦ Screw shaped ◦ Tapered and screw shaped  Subperiosteal frame like implants  Trans mandibular implants

15. • Endosseous implant: Implant is placed directly into the socket which is prepared by using a series of specially prepared drills.

16. • Subperiosteal implant: Custom fabricated framework of metal that is supraalveolar (on top of the bone) but beneath the oral tissues .

17. • Transosteal implant : These are non- osseointegrated staple implant which are used in mandibular anterior sextant

18. Classification based on Attachment mechanism of Implant

19. Classification based on macroscopic body design of implant :

20. • Threaded implants : These implants are threaded into bone recipient site like a screw with a handpiece or wrench after drilling a hole slightly smaller in diameter than the implant. The threaded implants are more widely used because they usually provide superior initial stability in bone .

21. • Threadless/smooth implants: The cylinder shaped, threadless implants are tapped into a recipient hole that is similar to the diameter of the implant body

22. Classification based on implant material :

23. Classification based on surface of the implant :

24. ‰ IMPLANT surface characteristics (micro design): • Additive surface treatment : – Titanium plasma spraying (TPS). – Hydroxyapatite (HA) coated surface . • Subtractive surface treatment : – Blasting with titanium oxide/aluminium oxide. – Acid-etched surface. • Modified surface treatment: – Laser induced roughened surfaces. – Ion implantation. – Oxidized surface treatment.

25. Titanium plasma spray: The TPS surface has been reported to increase the surface area of the bone — implant interface It acts similarly to a three dimensional surface, which may stimulate adhesion osteogenesis. TPS—porous or rough titanium surfaces have been fabricated by plasma spraying a powder form of molten droplets at high temperatures.

26. Hydroxyapatite coatings: Hydroxyapatite coatings are available with same roughness and increased functional surface area as TPS .

27. Blasted surface: The surface is blasted with titanium dioxide (TiO2 ) particles or aluminium oxide (Al2 O3 ) particles. Blasting technique is used to enhance implant surface topography with micro to macroscopic hills, valleys and indentations .

28. Acid-etched surfaces: Acid-etching is performed by bathing titanium base in hydrochloric acid (HCl), sulfuric acid (H2 SO4 ), hydrogen fluoride (HF) and nitric acid (HNO3 ) in different combinations. The roughness before etching, the acid mixture, the bath temperature and the etching time all affect the acid-etching process

29. Sandblasted and acid-etched surfaces: Implants are blasted with 250–500 μ m corundum grit followed by acid-etching in a hot solution of HCl and H2 SO4 . Sandblasting produces macroroughness onto which acid-etching superimposes microroughness .

30. Laser : Laser ablation is a technique that can be used to produce a surface with predetermined reproducible characteristics. Implants are modified to produce a controlled, micron-sized surface, with topographical features on the flanks of the threads. Excimer laser is used to create roughness over the implant surface

31. SOFT TISSUE INTERFACE

32. Clinical features of peri-implant mucosa: The clinically healthy gingiva and peri-implant mucosa has a pink color and a firm consistency. Radiographic features of peri-implant mucosa : The alveolar bone crest is usually located about 1 mm apical to a line connecting the cemento-enamel junction of neighboring teeth. The marginal termination of the bone crest is usually close to the junction between the abutment and fixture part of the implant system .

33. Histological features of peri-implant mucosa: The mucosal tissues around intraosseous implants form a tightly adherent band. This band is primarily composed of a dense collagenous lamina propria covered by stratified squamous keratinizing epithelium. The junctional and barrier epithelia are about 2 mm long and the zones of supra-alveolar connective tissues are between 1 mm and 1.5 mm high. Both epithelia are via hemidesmosomes attached to the implant surface.

34. The main attachment fibers (the principal fibers) invest in the root cementum of the tooth, but at the implant site the corresponding collagen fibers are nonattached and run parallel to the implant surface, owing to the lack of cementum. The sulcus around an implant is lined with sulcular epithelium that is continuous apically with the junctional epithelium

35. Schematic representation showing attachment apparatus for implant peri-implant mucosa. (No periodontal ligament fibers and cementum) Schematic representation showing attachment apparatus of tooth

36. Schematic representation showing probe in position at (A) tooth site ; (B) implant site (No periodontal ligament fibers and cementum

37. HARD TISSUE INTERFACE

38. Histologically, osseointegration is defined as the direct structural and functional connection between ordered, living bone and the surface of a load-bearing implant without intervening soft tissues Osseointegration Clinically , osseointegration is the asymptomatic rigid fixation of an alloplastic material (implant) in bone with the ability to withstand occlusal forces. The hard tissue interface is a fundamental requirement for and an essential component of implant success.

39. Branemark in 1990, then gave a modified definition of his own – ◦ “A continuing structural and functional coexistence, possibly in a symbolic manner, between differentiated, adequately remodeling, biologic tissues and strictly defined and controlled synthetic components providing lasting specific clinical functions without initiating rejection mechanism .”

40. Pre requisites for osseointegration : Material and surface properties ◦ Bio inert materials  Titanium ◦ Rough surfaces  Improve adhesive strength  Favours bone deposition  Degree of mechanical interlock Primary stability and adequate load ◦ Requires perfect stability ◦ Exact adaptation and compression of the fragments

41. Biologically determined program of osseointegration can be subdivided into three stages. Incorporation by woven bone formation. 2. Adaptation of bone mass to load (lamellar and parallel—fibered bone deposition) 3. Adaptation of bone structure to load (bone remodeling).

42. Stages of osseointegration : Healing of bone around implant/

43. Key factors for osseointegration :

44. Comparison of tooth and implant support structures: Tooth Implant Connection Cementum, bone and periodontal ligament Osseointegration, bone functional ankylosis Connective tissue 13 groups: Perpendicular to tooth surfaces Only 2 groups: Parallel and circular fibers No attachment to the implant surface and bone Biologic width JE: 0.97–1.14 mm CT: 0.77–1.07 mm BW: 2.04–2.91 mm JE: 0.97–1.14 mm CT: 0.77–1.07 mm BW: 2.04–2.91 mm Vascularity Greater; supraperiosteal and periodontal ligament Less; supraperiosteal Probing depth 3 mm in health 2.5–5.0 mm (depending on soft tissue depth) Bleeding on probing More reliable Less reliable

46. Newman, Takei, Klokkevold, Carranza. Carranza’s Clinical Periodontology, 10th Edition and 11th Ed. PHILLIP’S – SCIENCE OF DENTAL MATERIALS – Kenneth J. Anusavice , PhD ,DMD Textbook of periodontics , Shalu batla References :

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