Notes on Dental Implants

INTRODUCTION TO DENTAL IMPLANTS

  • Presenter: Prof. Otasowie D. Osunde, BDS, PhD, FWACS, FAOCMF
  • Affiliation: Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Calabar, Calabar.

OUTLINE

  • Introduction
  • Types of Dental Implants
  • Osseointegration
  • Advantages and Disadvantages
  • Implant Materials
  • Parts of Implant
  • Indications
  • Contraindications
  • Pre-operative Assessment and Treatment Planning
  • Treatment Techniques
  • Complications
  • Implant Failure

INTRODUCTION

  • Dental Implant:
    • Definition: A surgical component (anchor) implanted into oral tissues (beneath mucosa, periosteal layer, or within bone) to provide permanent support for fixed or removable dental prosthesis.
    • Composition: Made from alloplastic material, regarded as biocompatible, biofunctional, and permucosal device.
    • Purpose: Major treatment modality for replacing missing teeth, particularly effective for complete and partial edentulism.

ADVANTAGES OF DENTAL IMPLANTS

  • High Success Rate: 97% success rate over 10 years.
  • Decreased Risk of Caries: Lower risk of caries and endodontic issues in adjacent teeth.
  • Bone Preservation: Maintenance of bone in edentulous sites.
  • Reduced Sensitivity: Decreased sensitivity in adjacent teeth compared to traditional fixed partial dentures.

TYPES OF DENTAL IMPLANTS

  1. Transdental Implants (Endodontic Implants)

    • Definition: Smooth and/or threaded pin implant extending through the root canal into periapical bone, stabilizing a mobile tooth.
    • Function: Stabilization of remaining natural teeth; increases root-to-crown ratio for better arch stability.

  2. Transosteal Implants

    • Features: Composed of a metal plate with retentive pins against the inferior border of the mandible, penetrates full thickness of the mandible.
    • Uses: Attach to overdenture-type prosthesis; also called mandibular staple implant or transmandibular implant.

  3. Subperiosteal Implants

    • Definition: Placed beneath periosteum, overlying bony cortex, composed of cast metal framework.
    • Components:
      • Substructure: Fits on the ridge beneath periosteum for prosthesis support.
      • Abutment: Protrudes through mucosa for prosthesis retention.
      • Superstructure: Framework within removable dental prosthesis fitting onto abutments.

  4. Endosteal Implants

    • Definition: Embedded into the basal bone for prosthesis support.
    • Classifications:
      • Root Form Implant: Adequate bone required; available in several forms (cylinder, screw, combination).
      • Blade Form Implant: Used when bone width is insufficient, suitable for full arch edentulous cases.
    • Additional Types: Include immediate implants and transient implants.

OSTEOINTEGRATION

  • Definition: Key biologic and biophysical process in dental implant therapy for reliably replacing missing teeth.
  • Histological Definition: Direct structural and functional connection between living bone and implant surface without intervening soft tissue.
  • Primary Goal: Achieve and maintain an intimate bone-to-implant connection known as dental osseointegration.
    • Clinical Definition: Rigid fixation of an alloplastic material (the implant) in bone able to withstand occlusal forces.

FACTORS DETERMINING SUCCESS OF OSTEOINTEGRATED IMPLANTS

  1. Implant Biocompatibility: Compatibility of foreign material (implant) with living organism, existing harmoniously with the biological environment.
  2. Implant Design: Cylindrical designs preferred; unsuitable designs may result in insufficient stability leading to micro-movements and failure.
  3. Implant Surface Texture: Mild surface roughness beneficial for osseointegration, while overly smooth or excessively rough surfaces can hinder integration.
  4. Host Site Quality: Quality and condition of bone directly influence osseointegration success.
  5. Surgical Technique: Minimizing trauma, using sharp instruments, and maintaining cooling during drilling.
  6. Infection Control: Following surgical protocols to avoid infections, especially from the periodontium.

ADVANTAGES OF DENTAL IMPLANTS

  1. Bone Preservation: Prevents resorption of bone supporting teeth after extraction, preventing facial collapse and maintaining prosthetic function.
  2. Functionality: Implants can minimize harmful forces on remaining ridges; implants provide better chewing efficiency compared to traditional replacements.
  3. Aesthetic Quality: Implants offer a natural appearance as they emerge from the soft tissue.
  4. Stability and Retention: Enhanced stability and retention through the process of osseointegration.
  5. Comfort: Reduction of flanges on prosthetics improves comfort during use.

DISADVANTAGES OF DENTAL IMPLANTS

  1. Costs: Typically more expensive than alternative tooth replacement methods.
  2. Patient Eligibility: Not suitable for medically compromised patients who cannot undergo surgery.
  3. Healing Time: Requires a lengthy healing process and complex fabrication procedures.
  4. Patient Compliance: Requires significant patient cooperation for follow-up visits and aftercare.
  5. Placement Limitations: Anatomic constraints limit universal placement methods.

IMPLANT MATERIALS

  • Categorized based on chemical composition and biological response:
    • Bio-tolerant Materials: Low-grade tissue reactions, examples include stainless steel and gold alloy.
    • Bio-inert Materials: Direct contact with bone with minimal reaction, examples are titanium and ceramics.
    • Bio-active Materials: Promote osteogenic activity, examples include bio-ceramics and bio-glass.
    • Bio-inert and Structure Osteotropic Materials: E.g., titanium with rough surfaces that bond physically and chemically to bone.
  • All implant materials must exhibit properties of biocompatibility, toughness, strength, and resistance to corrosion, wear, and fracture.

PARTS OF IMPLANT

  1. Implant Body: Portion inserted into bone.
  2. Cover Screw: Covers implant body during osseointegration; prevents soft tissue invasion.
  3. Transmucosal Extension: Encourages development of perimucosal seal around the implant.
  4. Abutment: Supports and retains prosthesis/superstructure (can be screw or cement retained).
  5. Hygiene Cover Screw: Optional; used in screw-retained prostheses.
  6. Transfer Coping: Used to position an analogue during impressions.

INDICATIONS FOR DENTAL IMPLANTS

  • Lack of retention/stability for removable dentures.
  • Functional discomfort with removable dentures.
  • Psychologic factors preventing denture use.
  • Single tooth replacement with healthy adjacent teeth.
  • Tooth agenesis and conservative treatment demands.
  • Edentulous patients unable to tolerate conventional prostheses.
  • Difficult prosthetic situations need implants for stability.
  • Retaining maxillofacial prostheses (e.g., obturators).

CONTRAINDICATIONS

  1. Systemic health issues precluding surgery (e.g., uncontrolled diabetes).
  2. Poor oral hygiene.
  3. History of heavy smoking or psychological disorders.
  4. Pathologies of hard or soft tissue.
  5. Young patients under 18 due to incomplete bone formation.

PRE-OPERATIVE ASSESSMENT AND TREATMENT PLANNING

Medical History

  • Absolute Contraindications: Acute illness, uncontrolled systemic disease, specific diseases or damage at the potential implant site.
  • Relative Contraindications: Osteoporosis, immunocompromised disorders, medications like bisphosphonates.

Psychological Assessment

  • Considerations include psychiatric issues, cooperation levels, and irrational fears.
  • Tobacco and substance use scrutinized due to their effects on healing.

Dental History

  • Important to consider patient’s history with oral hygiene and previous dental experiences.

CLINICAL EXAMINATION

Intraoral Examination and Records

  • Assess health of existing teeth, soft and hard tissues.
  • Check restorative integrity, periodontal status, occlusion, and jaw relationships.
  • Examine:
    • Edentulous ridge anatomy
    • Soft tissue quality: keratinization, thickness, pathology.

Diagnostic Casts and Photographs

  • Study models and photographs essential for treatment planning. Evaluate:
    1. Occlusal relationships
    2. Arch relationships
    3. Inter-arch space
    4. Arch form and symmetry
    5. Measurement planning for implant placement.