DD - Perio from pg - 151 - 200

Implant Placement and Surgical Considerations

• A low smile line indicates that the gingival-restorative interface is not visible when smiling, making esthetic compromises more acceptable.
• A thick periodontal biotype means thicker, denser gingiva, less prone to recession, and less likely to show implant or abutment.
• Implants do not respond to orthodontic forces due to the lack of a periodontal ligament.
• Certain implants can be used for temporary anchorage during orthodontic treatment.

Assessment of Implant Patients

• Direct palpation of bone contours is essential to judge adequate bone volume.
• Cross-sectional imaging is superior to 2D radiography and is the standard of care.
• Limitations of mouth opening ability may preclude implant placement.

Treatment Planning

• Cephalometric radiographs help predict jaw and bone growth patterns.
• When planning mandibular implant locations, the inferior alveolar nerve's path must be considered.
• The implant location should be at least 5 mm anterior to the mental foramen.
• The osteotomy preparation should end 2 mm away from vital structures.

Implant Design and Abutment Selection

• Two-stage systems involve initial placement, primary closure, and secondary exposure of the abutment.
• One-stage systems place the implant with the abutment exposed to the oral cavity.
• Abutment selection is critical, and the ideal type is determined during treatment planning.
• Abutments can be used to compensate for implant angulation and provide adequate retention.

Implant Maintenance and Complications

• Probing depths are generally deeper around implants than natural teeth.
• Changes in attachment level around an implant indicate peri-implantitis.
• Implant surfaces can be damaged by metal instruments, and cleaning should be done with plastic instruments.
• Plaque forms on rough surfaces, but not smooth surfaces.
• Epithelial attachment on a roughened surface is identical to a natural tooth.

Patient Considerations

• Advanced patient age is not a contraindication to implant treatment.
• Any condition that impairs the patient's ability to heal should be considered a contraindication.
• Serious psychiatric conditions, such as psychoses, are contraindications.
• Smoking is not a contraindication, but failure rates are higher.

Platform Switching

• Combining an abutment of a particular diameter with a non-matching diameter implant reduces bone remodeling and bone loss.
• This combination is advantageous, but different designs have typical patterns of bone remodeling.

Bone Remodeling and Adjacent Implants

• A minimum of 3 mm of bone should remain between adjacent implants.
• If the implants are closer than 3 mm, bone loss is likely.
• Oral hygiene efforts are compromised if implants are too close together.
• Maintaining or creating an esthetic papilla between adjacent implants is a major challenge.

Inflammation

• Inflammation is an observable alteration in tissues associated with changes in vascular permeability and dilation.

• The three stages of inflammation are immediate, acute, and chronic.

• Leukocytes, such as mast cells, peripheral dendritic cells, neutrophils, and monocytes/macrophages, play a crucial role in inflammation.### Leukocyte Migration

• Leukocytes squeeze between contracted endothelial cells and migrate into the extravascular space through a process called diapedesis.

• Once in tissue, leukocytes are attracted by activated complement and begin to migrate to the site of injury or infection.

Chemotaxis

• Leukocytes (specifically PMs) have surface receptors for chemotactic agents (e.g. C5a, TNF, IL-8, LTB4, IL-1, IFN-γ).
• These receptors cause leukocytes to move in the direction of increasing concentrations of the chemotactic substance.

Phagocytosis

• When leukocytes (specifically PMs) arrive at the site of tissue injury or microbial invasion, they become active and begin engulfing bacteria, forming a phagosome.
• The phagosome combines with lysosomal granules to form a phagolysosome, where digestion of the engulfed particle occurs.

Immune System Cells

• All cells of the immune system originate from a hematopoietic stem cell in the bone marrow, which gives rise to two major lineages: myeloid and lymphoid progenitor cells.
• These progenitors give rise to myeloid cells (monocytes, macrophages, dendritic cells, megakaryocytes, and granulocytes) and lymphoid cells (T cells, B cells, and natural killer cells).

Cell Receptors

• Cells possess receptors, which are molecules on the cell surface that enable the cell to interact with other molecules or cells.
• Receptors reflect and dictate the function of cells.

Mast Cells

• Mast cells are important in immediate inflammation (anaphylaxis and allergic responses).
• They possess receptors for complement components (C3a and C5a) and receptors for the Fc portion of antibody molecules IgE and IgG.

Dermal Dendrocytes (Histiocytes)

• Dermal dendrocytes are distributed near blood vessels and possess receptors for the complement component C3a, participating in immediate inflammation.

Peripheral Dendritic Cells (DCs)

• Peripheral DCs are leukocytes with dendrites and are important in antigen processing and presentation to cells of the specific immune response.

Neutrophils and Monocytes/Macrophages

• Neutrophils and monocytes/macrophages are phagocytic leukocytes.
• Neutrophils are the predominant leukocyte in blood and are suited for rapid responses.
• Monocytes are referred to as macrophages when they leave the blood and present antigen to T cells.

Lymphocytes

• The three main types of lymphocytes are distinguished based on their receptors for antigens: T lymphocytes, B lymphocytes, and natural killer (NK) cells.
• T cells recognize diverse antigens using a low-affinity transmembranous complex, the T-cell antigen receptor (TCR).
• B cells recognize diverse antigens using the B-cell antigen receptor (BCR).
• Natural killer (NK) cells recognize and kill certain tumor and virally infected cells.

Chronic Inflammation

• Chronic inflammation is characterized by a slow onset and persists for weeks or more.
• The main cells involved in chronic inflammation are macrophages and lymphocytes.
• Macrophages and lymphocytes are interdependent, with the activation of one stimulating the actions of the other.

Cells Involved in Chronic Inflammation

• Macrophages: circulate as monocytes, reach the site of injury within 24 to 48 hours, and transform into activated macrophages.
• T cells: antigen-activated, release macrophage-activating cytokines.
• B cells: terminally differentiated, produce antibodies.
• Plasma cells: produce antibodies.
• Eosinophils: found especially at sites of parasitic infection or allergic (IgE-mediated) sites.