Comprehensive Periodontology and Dental Hygiene Study Guide

The Components and Structure of the Periodontium

The periodontium is defined as the functional unit of tissues that surrounds the teeth and attaches them to the jawbone. It consists of four primary components: the periodontal ligament (PDL), the cementum, the gingiva, and the alveolar bone. The alveolar bone itself is categorized into several distinct types. The alveolar bone proper, also known as the cribriform plate, serves as the bony socket or lining essentially housing the root of the tooth. Surrounding this is the cortical bone, which provides structural support to the socket. Between the cortical bone and the alveolar bone proper lies the cancellous bone, characterized by a spongy, lattice-like architecture that acts as a filler. The entire outer surface of the bone is covered by the periosteum, a specialized layer of connective soft tissue. The periodontal ligament (PDL) serves the dual function of holding the tooth securely within its socket and providing a necessary blood supply to the tooth. The term "perio" literally translates to "around."

Periodontal and Gingival Fiber Groups

The periodontal ligament is comprised of various fiber groups with specific locations and functions. The Alveolar crest group and Horizontal group provide stability. The Oblique fibers are the most numerous and are responsible for absorbing chewing forces. Apical fibers prevent the tooth from being pulled out of the socket. Interradicular fibers are unique in that they are only found in multi-rooted teeth, where they reside in the furcation area. A specialized set of fibers known as Sharpey's Fibers acts to attach the PDL to both the cementum and the bone. Within the gingiva, several fiber groups provide structural support and stability to the gums, protecting the connection to the tooth or bone. These include the Alveologingival, Circular, Transgingival, Dentogingival, Transseptal (connecting one tooth to the next), Periostogingival, Intergingival, Intercircular, and Interpapillary groups. These landmarks and fibers anchor the tooth to the bone, resist lateral forces, and resist horizontal movement.

Histology of the Periodontium in Health

In a healthy state, the linear distance from the Cementoenamel Junction (CEJ) to the crestal bone is approximately $1-2\,mm$. The Junctional Epithelium (JE) is a critical component that joins the gingiva to the tooth at or near the CEJ. This tissue type is thin and non-keratinized. It serves as a protective barrier between biofilms and the underlying connective tissue of the periodontium. Cell junctions are vital for tissue integrity. A Desmosome is a specialized cell junction that connects two neighboring epithelial cells and their respective cytoskeletons. Conversely, a Hemidesmosome is a specialized cell junction that connects epithelial cells to the basal lamina.

Osseous Defects and Periodontal Pockets

Osseous defects are bone deformities resulting from periodontitis. Periodontal pockets are classified based on the relationship between the JE and the alveolar crest. Horizontal pockets, also termed suprabony pockets, occur during horizontal bone loss when the JE remains coronal to the alveolar crest. Vertical pockets, or infrabony pockets, occur during vertical bone loss where the JE is apical to the alveolar crest. Infrabony defects are caused by bone resorption in an uneven, oblique direction and typically affect only one tooth. These are classified by the number of remaining bony walls: a 3-wall defect is missing one wall, a 2-wall defect is missing two walls, and a 1-wall defect is missing three walls.

Microbiology and the Inflammatory Response

Several specific bacteria are strongly associated with periodontal disease, including P. gingivalis, T. forsythia, T. denticola, F. nucleatum, and A. actinomycetemcomitans. These bacteria vary in their oxygen requirements: Aerobic bacteria require oxygen; Anaerobic bacteria can survive without it; Facultative anaerobes can survive with or without oxygen; and Obligate anaerobes cannot survive in the presence of oxygen. Periodontal pathology also presents as Dehiscence, which is the loss of bone on one aspect of the tooth leaving the root covered only by soft tissue, or Fenestration, a "window" of bone loss bordered by alveolar bone on its coronal aspect. Inflammation is the body's protective response; Acute inflammation is beneficial, whereas Chronic inflammation is injurious. The five classic signs and symptoms of inflammation are heat, loss of function, redness, swelling, and pain.

Host Response Factors and Chemical Mediators

The body utilizes various cells and proteins to manage infection and inflammation. Prostiglandins cause pain and inflammation and are responsible for triggering osteoclasts. Mast cells release inflammation mediators and histamine, which increase blood flow. Cytokines act as messengers to affect the behavior of nearby cells. Antibodies neutralize or coat bacteria and activate the complement system. Phagocytes initiate the process of consuming bacteria. Polymorphonuclear Leukocytes (PMNs), also known as neutrophils, are the first responders to invaders and are specific to biofilm bacteria; pus is largely composed of PMNs. Osteoclasts are responsible for breaking down bone. B Lymphocytes produce antibodies, while T Lymphocytes (both types of White Blood Cells or WBCs) produce cytokines. Endotoxins are harmful proteins released from bacterial cells that act on host cells from a distance.

Pathogenesis and Bacterial Accumulation

Chemotaxis is the process where inflammatory cells are attracted to a stimulus, such as trauma or bacteria. Being immunocompromised means having a weakened immune system, making it difficult for the body to fight infection. Factors including chemotherapy, malnutrition, HIV/AIDS, and certain medications can lead to this state. Gingivitis is the reversible inflammation of gingival tissues, while periodontitis involves the irreversible loss of connective tissue and bone. The process of bacterial accumulation occurs in five phases: 1) The formation of the Acquired Pellicle, which protects enamel from acid and forms within seconds to minutes; 2) Bacteria attach to the pellicle using structures like fimbriae; 3) New bacteria join; 4) A slime layer is formed, which is a slimy substance that protects bacteria from external factors; 5) Colonization occurs in mushroom-shaped structures containing different resistant bacteria.

Clinical Definitions of Gingivitis and Periodontitis

Gingivitis involves reversible tissue damage with no apical migration of the JE. Clinically, gums may appear red, bulbous, cratered, or show "punched out" interdental papillae (IDP) and rolled margins. The tissue may be edematous (soft, spongy, shiny), show a loss of stippling, or be enlarged/fibrotic with bleeding on probing (BOP). Gingival enlargement can be caused by puberty or medications such as Dilantin (anti-seizure), Cyclosporine (immunosuppressant), and Calcium Channel Blockers (antihypertensive). Biofilm-induced gingivitis shows clinical signs within $2-14\,days$ if the biofilm is not disrupted. Periodontitis is irreversible and characterized by the apical migration of the JE, loss of connective tissue, and loss of alveolar bone. Clinical signs include bluish, purple, or red spongy/fibrotic tissue, swelling, recession, bleeding, and exudate (suppuration) in pockets measuring $4\,mm$ or greater.

Measurements and Traumatic Occlusion

Clinical Attachment Level (CAL) is the true measurement of attachment loss, measuring from the CEJ to the JE. To calculate CAL when recession is present, use the formula: $\text{probe depth} + \text{clinical margin level} = \text{CAL}$. If enlargement is present, the formula is: $\text{probe depth} - \text{clinical margin level} = \text{CAL}$. Mucogingival involvement occurs when a pocket extends to or beyond the mucogingival junction (MGJ) into the alveolar mucosa. Occlusal trauma is divided into two types: Primary occlusal trauma involves excessive forces on teeth with normal periodontal support, while Secondary occlusal trauma involves normal or excessive forces on teeth with already compromised periodontal support. Desquamative gingivitis, also known as gingirosis, manifests as painful, erosive lesions.

Specific Conditions and Systemic Associations

Gingivitis can be associated with hormones during puberty, the menstrual cycle (bleeding/sensitivity), and pregnancy. During pregnancy, specifically between months $2-3$, a pyogenic granuloma may form, which might subside after birth. Malnutrition, specifically Vitamin C deficiency, can lead to hemorrhagic, swollen gingiva. Infections like Streptococcal infection, Syphilis, and Gonorrhea can manifest orally. Necrotizing Gingivitis (NG) is characterized by punched-out IDP, Fetor oris (bad breath), and a pseudomembrane. Primary Herpetic Gingivostomatitis is the initial herpes infection in children, causing odor and vesicles. Periodontal disease is linked to systemic health; Active disease in pregnancy increases the risk of preterm babies due to prostaglandins causing contractions. There is a strong connection between periodontitis and cardiovascular disease via C-reactive proteins (CRP). High CRP levels, present in both perio-inflammation and cardiovascular conditions, increase the risk of atherosclerosis.

Diabetes and Abscess Types

Diabetes requires insulin to convert sugar and starch to energy. Diabetics often have reduced PMNs and poor healing. A well-controlled diabetic will have an $HbA1c < 7\%$ and an $FPG < 100$. Diabetics have a $2-3\,\text{times}$ greater risk of periodontitis. Abscesses are classified by origin: A Periodontal abscess is a localized, purulent infection with rapid bone loss and often a fistula; it is vital and treated with debridement. An Endodontic or Periapical abscess is caused by caries or trauma, involves the tooth apex, is non-vital, hurts to bite down, and requires a Root Canal. A Gingival abscess is caused by a foreign object in the sulcus, involves no bone loss, and is treated with debridement and subgingival irrigation. Pericoronitis is inflammation around the crown of a partially erupted tooth, treated with debridement, extraction, or antibiotics if fever is present.

Manifestations of Mucous Membrane and Other Disorders

Necrotizing Periodontitis (NP) includes all symptoms of NG plus bone loss and is often seen in HIV patients. Factors predisposing to NG include stress, poor nutrition, alcohol consumption, and fatigue. Mucous membrane pemphigoid, also called cicatricial pemphigoid, is a chronic vesiculobullous disease where the Nikolsky Sign is used for diagnosis; if the tissue is wiped, a blister forms immediately. It can affect the mouth, nose, eyes, and genitals. Lichen planus is characterized by itchy areas and Wickham's striae, which is a white, lace-like pattern that will not wipe off.

Staging, Grading, and Dental Implants

Staging and grading allow clinicians to classify the extent and severity of periodontitis to establish a treatment plan. Staging is based on CAL severity, complexity, radiographic bone loss (RBL), and tooth loss. Grading determines the rate of progression. Dental implants consist of three parts: the crown, the abutment, and the implant body. Peri-implant mucositis is reversible inflammation around the implant without bone loss, treated with debridement and improved home care. Peri-implantitis is an irreversible chronic condition affecting hard and soft tissues, characterized by severe bone loss and mobility.

Diagnostics and Mobility Classes

Active periodontitis is often latent, characterized by periods of destruction and inactivity; the whole mouth does not need to be active at once. Staging and grading require at least $2$ non-adjacent teeth. Mobility is determined using the ends of a probe and a mirror. Class I mobility involves slight horizontal movement of $< 1\,mm$. Class II involves horizontal movement of $> 1\,mm$. Class III involves significant horizontal and vertical movement. Assessment involves checking probing depth, gingiva margin, MGJ, mobility, furcation, suppuration, and BOP. Probes used include the Williams and the PCP-UNC (which has a total length of $12-15\,mm$, uses a thick band at $4/5\,mm$, $9/10\,mm$, and $14/15\,mm$, and is missing markings at $4$ and $6$).

Clinical Protocols and Systemic Risk Factors

The standard regimen for prophylaxis is Amoxicillin $2\,g$. For patients allergic to Amoxicillin, alternatives include Cephalexin, Azithromycin ($500\,mg$), or Doxycycline ($100\,mg$). Systemic diseases that increase periodontal risk include Down syndrome, Leukemia, AIDS/HIV, and Papillon-Lefevre syndrome. Down syndrome patients often present with a protruding tongue, prognathic profile, strong gag reflex, mouth breathing, delayed tooth eruption, and small midface. They have a reduced immune system, abnormal PMN phagocytosis, impaired fibroblast motility, and decreased wound healing. Leukemia is cancer of the blood-forming tissues; symptoms include lethargy, musculoskeletal pain, easy bruising, and spontaneous bleeding (due to abnormal WBCs and platelets). AIDS/AIDS manifestations include Kaposi's sarcoma, Hairy leukoplakia, Oral candidiasis, Linear Gingival Erythema, and Herpes. Papillon-Lefevre syndrome is a genetic condition causing rapid bone loss and the loss of primary teeth by age $4$ and permanent teeth by age $14$.

Tobacco, Osteoporosis, and Treatment Phases

Osteoporosis is a degenerative bone disease affecting bone density; it is common in menopausal women and makes it easier for bacteria to destroy bone. Tobacco use reduces oxygen levels in the oral cavity, causing bone loss, gingival recession, and reduced immune response. Smoking is a significant risk factor due to nicotine, an anaerobic environment, heat, and vasoconstriction. Treatment of periodontal disease occurs in phases: 1) Preliminary phase (emergency control); 2) Phase I - Etiologic (Scaling and Root Debridement, oral hygiene); 3) Phase II - Surgical (for Stage III or greater); 4) Phase III - Completion of restorations (Prosthetics/Ortho); and 5) Phase IV - Maintenance (periodic recalls). Documentation often follows the SOAP format: Subjective, Objective, Assessment, Planning.

Nonsurgical Therapy and Healing

Nonsurgical periodontal therapy includes prophylaxis (for pockets $4\,mm$ or less) and periodontal debridement/SRP (for pockets $5\,mm$ or more). The goal is to remove the etiologic agent (plaque/calculus). Root debridement strokes should be light and longer. Patients may experience sensitivity after debridement because dentin tubules are exposed (treated with fluoride, rinses, or varnish). Gingival curettage involves removing diseased pocket lining but is not typically done in Connecticut. Gingival health restoration takes $7\,days$, most healing occurs in $4-5\,weeks$, and the JE reattaches in $3\,mos$. Instruments become dull after approximately $15\,strokes$. Re-evaluation occurs at $4-6\,weeks$. Scaling is often done by quadrant (UR/LR or UL/LL) to allow the patient a side to eat on.

Periodontal Surgical Procedures and Post-Op Care

Types of surgery include Gingivectomy (tissue removal), Flap (to debride root surfaces), and Gingival grafts (to treat mucogingival involvement and reduce sensitivity). Guided Tissue Regeneration (GTR) aims to regenerate bone, cementum, and the PDL by blocking gum epithelial cells to allow osteoblasts and fibroblasts to work. Crown lengthening exposes more tooth structure for prosthetic restoration. Sutures close wounds, and periodontal packs protect the area (though packs do not reduce bleeding). Graft types include: Autograft (yourself, e.g., hard palate), Allograft (another person), Xenograft (animal tissue), and Alloplast (synthetic). Post-operative instructions include using ice ($20\,min$ on/$20\,min$ off), a soft food diet, resting, and avoiding negative pressure (rinsing/swishing). Bleeding is normal for the first $24-48\,hours$.