Implant Dentistry: Terminology

Terminology in Implant Dentistry

• Implant dentistry terminology differs significantly from other clinical dentistry disciplines due to specialized instrumentation, varied implant types and designs, and diverse surgical and restoration techniques.
• The field has developed a generic nomenclature system for instruments and components, aligning with terms from the International Congress of Oral Implantologists (ICOI) and the American College of Prosthodontists (ACP) to reduce confusion from proprietary naming systems.

Osseointegration

• Osseointegration, a concept pioneered by Per-Ingvar Branemark, refers to the direct contact between an implant and living bone at a microscopic level.
• This process, discovered accidentally in 1952, involves titanium chambers becoming firmly affixed to bone, demonstrating a strong bone-to-titanium bond.
• It differentiates modern implant methods, which aim for bone regeneration, from older techniques that often resulted in a soft tissue interface.
• A clinically successful implant is characterized by rigid, asymptomatic fixation, no radiographic evidence of radiolucency (gap between implant and bone), marginal bone loss of less than 0.2 mm annually after the first year, and absence of pain, discomfort, or infection.
• The biomechanical concept of secondary stability or osseointegration is the structural and functional connection between newly formed bone and the implant surface.
• Approximately 60% to 70% of the implant surface establishes contact with bone during the remodeling phase, a measure known as bone-to-implant contact (BIC).
• Primary stability is the initial mechanical or frictional stability obtained during placement, dependent on implant macrostructure and surgical protocol.
• Secondary stability, developed as bone heals, is responsible for long-term implant success.
• A "stability dip" occurs during bone remodeling when primary stability decreases as secondary stability increases.

Types of Dental Implants

• Dental implants are categorized by their placement within bone, with endosseous implants being the most common, placed directly into the alveolar or basal bone.
• Endosseous implants are primarily categorized as blade or root form implants.
• Blade implants have a flat shape, available in one- or two-piece designs, but their usage has decreased due to lower success rates (55% at 5 years, under 50% at 10 years).
• Cylinder or press-fit implants are straight cylinders inserted into the surgical osteotomy; their stability relies on a highly roughened surface texture to increase friction, and materials like hydroxyapatite, titanium plasma spray, and small metal balls are sintered onto the surface.
• Screw-shaped implants, exhibiting threads along most or all their length, are the most commonly used due to improved primary stability and simplified surgical protocols.
• One-piece implants integrate the abutment as part of the implant, while two-piece designs have an implant body for bone anchorage and a platform for connection to instruments, components, or prosthetics.
• Small diameter implants (SDIs), or mini-implants, are screw-shaped with diameters of 1.8 to 2.9 mm and lengths of 10 to 18 mm, indicated for patients with thin residual ridges or as an alternative to lateral ridge augmentation.

Implant Macrostructure and Threads

• Implant macrostructure, encompassing the overall shape, is designed to optimize placement, initial stability, and force distribution within the bone, primarily featuring screw shapes (parallel-sided or tapered).
• Parallel-sided screws, once standard, required tapping to create threads in the osteotomy site.
• Tapered screw designs, developed for increased primary stability and anatomical conformity, condense bone in areas of poor quality and distribute occlusal forces more effectively, reducing the likelihood of buccal and lingual wall perforation.
• Modern self-tapping implants, designed with aggressive apical shapes, eliminate the need for a separate tapping step, cutting their own way into the bone.
• Key thread terminology includes the crest (outer surface), root (inner surface), outer diameter (measured around the crest), inner diameter (measured around the root), helix angle (angulation between thread wall and perpendicular axis), pitch (distance between adjacent threads), and lead (axial insertion distance per full turn).
• Deeper threads and buttress threads generally improve primary stability, especially in lower quality bone, by distributing occlusal loads more effectively and minimizing shear forces compared to V-threads.
• Microthreads, small threads at the crestal or collar portion of the implant, help distribute forces from the collar and maintain crestal bone height.

Implant Surfaces and Connections

• Implant surfaces are modified via subtractive processes (acid etching, abrasive blasting with silicon/titanium, resorbable blast media) or additive processes (HA coating, TPS, anodization) to enhance surface roughness, promoting osseointegration, especially in poor bone quality.
• Optimal surface roughness (Ra) for osseointegration is typically between 1 and 2 µm.
• Implant connections are defined by their geometric elements, such as external hex (Branemark design) or internal connections (hexagon, octagon, trichannel), with internal connections generally offering better mechanical and restorative advantages.
• Platform switching, where the abutment is narrower than the implant at the connection, helps reduce bone loss around the implant and creates more soft tissue volume for improved esthetics.

Surgical Protocols and Bone Grafting

• The two-stage surgical protocol involves submerging the implant body under soft tissue until bone healing, followed by a second surgery to expose the implant and attach a healing abutment or prosthesis.
• The one-stage surgical approach places the implant and a temporary healing abutment in a single procedure, with the abutment emerging through the soft tissue.
• Immediate restoration places both the implant body and a prosthetic abutment during the initial surgery, with a provisional restoration attached simultaneously.
• Immediate placement involves placing implants into the alveolus immediately after tooth extraction, often called "emergency implants" for nonrestorable teeth.
• Bone grafting techniques are used to augment insufficient bone volume due to atrophy, trauma, or congenital deficiency, performed either before (site preparation) or at the same time as implant placement (simultaneous grafting).
• Ideal bone graft materials are biocompatible, bioactive (promoting cell differentiation), have a low infection incidence, are nontoxic and nonimmunogenic, maintain space and volume, are replaced by new bone, and have a resorption rate that matches bone formation.
• Types of bone graft materials include autogenous (harvested from the same patient, considered ideal), allografts (from cadavers of the same species), xenografts (from nonhuman sources), and alloplastic (synthetic substitutes).
• Guided bone regeneration (GBR) uses barrier membranes to protect bone defects from soft tissue ingrowth, allowing bone progenitor cells to develop uninhibited; membranes can be resorbable or nonresorbable.
• Surgical techniques for bone augmentation include onlay grafting (material applied over a defect), inlay grafting (material sandwiched between surgically separated jaw sections), ridge expansion (splitting the alveolar ridge longitudinally), and socket-shield technique (preserving buccal root part for tissue volume maintenance after extraction).
• Bone graft properties include osteogenesis (ability to produce new bone, only in fresh autogenous bone and marrow cells), osteoconduction (graft serving as a scaffold for bone healing), and osteoinduction (graft inducing stem cells to differentiate into bone cells, associated with bone growth factors).
• Maxillary sinus floor augmentation (MSFA) techniques, such as the lateral window technique or crestal sinus lift/sinus bump, are used to graft bone to the sinus floor, common for patients with inadequate posterior maxilla bone volume.

Surgical Instrumentation and Components

• Dental implant systems include surgical instrumentation kits, such as drills, drivers, wrenches, screw taps, and implant mounts.
• Implant drills are rotary cutting instruments that create an osteotomy (surgical opening in bone) without causing mechanical or thermal damage, designed to produce optimal size and shape for initial stability.
• Drivers engage screws (hexed, slotted, unigrip) during implant treatment.
• Implant mounts facilitate dental implant delivery to the surgical site and correct positioning, later removed for visual confirmation.
• Wrenches, including ratchet and torque wrenches, are manual instruments for applying specific torque during implant or prosthetic screw placement; torque controllers are electronic machines for the same purpose.
• The cover screw, or healing screw, occludes the implant connection when submerged during a two-stage procedure.
• A healing abutment connects to the implant and protrudes through soft tissue, used to guide tissue healing.
• Traditional implant designs (e.g., Branemark external hex) maintain consistent diameter from implant collar to abutment (platform matching), while newer designs reduce abutment diameter (platform switching) for stability and soft tissue esthetics.

Medical Evaluation for Dental Implants

• A comprehensive medical evaluation is crucial for dental implant treatment, encompassing current and past medical/dental history, medication use, allergies, social history, treatment type, duration, invasiveness, psychological status, urgency, and sedation.
• Patients over 60 often have medical conditions and take multiple medications, increasing the need for thorough evaluation.
• The medical history questionnaire and physical examination are primary tools for assessing risk, with additional emphasis on relevant systemic diseases and medications that may affect treatment.

Extraoral and Intraoral Examinations

• Extraoral and intraoral examinations evaluate the patient's face, neck, arms, and hands for features, facial symmetry, and anatomical landmarks, including the temporomandibular joint and occlusal opening.
• This helps identify any conditions that might complicate or contraindicate surgical and prosthetic procedures.

Vital Signs and Blood Pressure

• Vital signs (blood pressure, pulse, temperature, respiration, weight, height) are important components of the physical examination for implant patients.
• Blood pressure measurement, recommended in both arms with at least 2-3 minutes between readings, serves as a baseline and can indicate underlying cardiovascular disease.
• Normal blood pressure is <120/80 mm Hg; elevated is 120-129/<80; stage 1 hypertension is 130-139 or 80-89; stage 2 hypertension is >140 or >90.
• A diagnosis of hypertension requires at least two or more readings on separate occasions.
• Low blood pressure (<90/60 mm Hg) necessitates postponing elective surgery until physician consultation, as it may indicate dehydration, hypothyroidism, or over-medication.
• Blood pressure should be taken on the arm opposite the side of a mastectomy to avoid lymphedema.

Pulse and Temperature

• The pulse represents the force of blood against aortic walls, with a normal rate of 60-90 beats/min in relaxed adults; irregularities should prompt referral to a primary care provider.
• Sinus bradycardia (pulse <60 beats/min in nonathletes) or sinus tachycardia (pulse >100 beats/min in nonanxious patients) warrant medical consultation.
• An increased pulse rate can be due to exercise, anxiety, anemia, hemorrhage, or hyperthyroidism.
• Body temperature is checked using automated thermometers; temperatures >100.5°F (indicating infection/inflammation) or >102°F (requiring medical consultation) contraindicate implant surgery.

Respiration and Patient Height/Weight

• Respiration rates (normal 16-20 breaths/min) should be evaluated at rest; increased rates can indicate anxiety, anemia, or respiratory/cardiac disease, while hypoventilation requires airway assessment.
• Oxygen saturation should be maintained above 90%, sometimes requiring supplemental oxygen, especially for chronic COPD patients while adhering to their baseline oxygen levels.
• Height and weight are assessed to evaluate growth and development in adolescents (critical for timing implant placement) and to identify issues like malnutrition, obesity, or fluid retention in adults.

Laboratory Evaluation and Blood Tests

• Routine laboratory screening for dental implant patients, including urinalysis and blood samples, helps detect undiagnosed systemic diseases that may affect surgical outcomes.
• A complete blood count (CBC) evaluates white blood cells (WBCs), red blood cells (RBCs), and platelets, providing insights into infection, anemia, and bleeding disorders.
• Urinalysis screens for systemic diseases, with findings like glycosuria (sugar in urine) indicating possible diabetes.
• Renal function is monitored through creatinine levels and estimated glomerular filtration rate (eGFR), with declining eGFR potentially requiring medication adjustments.
• Blood urea nitrogen (BUN) levels indicate kidney and/or liver function; elevated levels can signal urinary tract obstruction, CHF, GI bleed, or dehydration.
• Bilirubin levels, a liver pigment, indicate liver health; elevated levels can suggest liver disease, bile duct issues, or jaundice.
• Aminotransferases (AST/SGOT and ALT/SGPT) are liver enzymes that, when elevated, indicate liver damage.
• Prothrombin time (PT) and International Normalized Ratio (INR) measure how long blood takes to clot, especially important for patients on anticoagulants; normal INR is 1.0, while therapeutic ranges vary (e.g., 2.0-3.0 for myocardial infarction prevention).
• Partial thromboplastin time (PTT) measures the contact activation pathway, used to monitor heparin therapy; normal range is 30-40 seconds.
• Platelet count, part of the CBC, is vital for blood clot formation; counts below 150,000 cells/mL (thrombocytopenia) can lead to significant bleeding.
• Thrombin time (TT) measures the activity of Factor Xa in forming fibrin; normal range is usually less than 20 seconds.
• Novel oral anticoagulants (NOACs) like warfarin and rivaroxaban affect clotting and require careful monitoring due to their varying effects on PT/INR and PTT.

Systemic Diseases and Oral Implants

• Systemic diseases significantly influence treatment planning and implant therapy, impacting bone metabolism and wound healing.
• Disorders affecting blood, such as anemia or bleeding disorders, as well as chronic renal conditions and chemotherapy status, necessitate CBC evaluation.
• Abnormal WBC counts can indicate infection, inflammation, or bone marrow disorders.
• Anemia or blood loss is assessed through RBC count, hemoglobin (Hb), and hematocrit levels; Hb levels below 10 g/dL may require further evaluation before surgery.
• Liver dysfunction, often associated with excessive alcohol consumption, can impair the production of clotting factors, making PT and PTT important tests.
• Diabetes is a key concern, with fasting glucose levels >120 mg/dL or HbA1c >8% potentially contraindicating implant surgery or requiring physician consultation.
• Bone diseases, parathyroid issues, and renal disease affect calcium and phosphorus levels, which are crucial for bone integrity and healing.

Radiographic Evaluation in Oral Implantology

• Radiographic imaging is essential for dental implant treatment planning, assessing bone quality, quantity, and anatomic structures.
• Traditional 2D modalities (periapical, panoramic) have limitations like distortion, magnification, and inability to show 3D bone dimensions.
• 3D imaging techniques, especially Cone Beam Computed Tomography (CBCT), are preferred for their high-resolution, dimensionally accurate information, lower radiation dose compared to medical CT, and on-site accessibility.
• Presurgical imaging (Phase 1) assesses bone characteristics, critical structures, and existing pathology.
• Surgical/intraoperative imaging (Phase 2) aids in implant positioning and verifies healing.
• Post-prosthetic implant imaging (Phase 3) monitors long-term stability and bone levels.
• Medical CT images provide Hounsfield Units (HUs) to quantify tissue density, while CBCT provides gray level density estimates.
• Artifacts, particularly beam hardening from metallic objects, can compromise CBCT image quality.

Surgical Anatomy for Dental Implants

• Understanding the surgical anatomy of the maxilla and mandible is critical for safe implant insertion and managing potential complications.
• The maxilla, pyramidal in shape, extends from the zygoma and includes key anatomical landmarks like the infraorbital foramen, maxillary tuberosity, and palatine bone.
• Sensory innervation of the maxilla involves the maxillary nerve (V2) and its branches, including the posterior, middle, and anterior superior alveolar nerves, and palatine nerves.
• Arterial supply to the maxilla mainly comes from the maxillary artery and its branches, with supplemental supply from other facial arteries.
• The mandible involves landmarks such as the mental foramen and bony ridges, with muscle attachments affecting bone resorption in edentulous areas.
• Muscles attached to the maxilla and mandible, such as the orbicularis oris, incisivus labii superioris, buccinator, mylohyoid, genioglossus, medial pterygoid, lateral pterygoid, temporalis, and mentalis, influence surgical approaches and potential complications.
• Sensory innervation of the lower jaw includes the inferior alveolar nerve and lingual nerve, which are susceptible to injury during implant procedures.