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Dental Science for Dental Assisting Exam Study Guide (page 2)

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Updated on Jun 23, 2011

Names of the Teeth

Central Incisors

These teeth are located at the midline of the face, at the anterior of the mouth. They are the teeth that are most visible when smiling. These teeth are used for cutting and tearing of food.

Lateral Incisors

These teeth are located next to the centrals, at the anterior of the mouth, and are smaller in size than the centrals. These teeth are also used for cutting and tearing of food.

Cuspids

These teeth are located at the corners of both arches and are the longest rooted teeth in the mouth. Cuspids are sometimes referred to as canines or “eye-teeth” because of their pointy shape. They are anterior teeth and are considered to be the cornerstone of the arches.

Premolars or Bicuspids

These teeth are located in the posterior of the mouth and used for chewing and grinding of food. They are smaller than the molars and can be single or double rooted, depending on the individual. There are two premolars in each quadrant: a first premolar and a second premolar.

Molars

These teeth are located in the posterior of the mouth and are used for chewing and grinding of food. There are three molars in each quadrant: first molar, second molar, and third molar (wisdom teeth). These teeth are multirooted and can have as many as four roots.

Tooth Surfaces

Mesial

This is the surface of the tooth closest to the midline. It is located interproximally, or in between the teeth.

Distal

This is the surface of the tooth that is the furthest distance away from the midline. It is located interproximally, or in between the teeth.

Lingual

This is the surface of the tooth closest to the tongue.

Facial/Buccal

This is the surface of the tooth closest to the face or cheek. Facial is the term used for the anterior teeth. Buccal is the term used for the posterior teeth. The two names designate the same area of the tooth but are site-specific to the area of the mouth.

Occlusal/Incisal

This is the surface of the tooth used for chewing or cutting of food. Occlusal is the term used for the chewing surface of posterior teeth, and incisal is the term used for the cutting edge of the anterior teeth. The two names designate the same area of the tooth but are site-specific to the area of the mouth.

Tooth Numbering Systems

Numbering systems are utilized as a means of communication and identification among dental team members. Documentation and insurance companies require a consistent format of charting procedures. There are three numbering systems that are utilized in dentistry.

Universal Numbering System

The Universal Numbering System is the most common in the United States and is approved by the American Dental Association (ADA). Teeth are numbered from 1 to 16 on the upper arch, beginning with the patient’s upperright quadrant. Teeth are numbered from 17 to 32 on the lower arch, beginning with the patient’s lower-left quadrant. The primary dentition is charted using letters instead of numbers. The primary teeth are lettered A–T.

ISO Numbering System

The International Standards Organization (ISO) numbering system is accepted by the World Health Organization (WHO) and used internationally. This numbering system assigns each quadrant a number—for example, UR quadrant = 1. Next, each quadrant numbers the teeth 1–8. The charting would look like this: 1, 8. This would be read as: upper-right third molar. This is true for both primary and permanent charting.

Palmer Notation System

This numbering system assigns a number and bracket to each tooth. For the primary dentition, a letter and a bracket are assigned to each tooth. The bracket designates the quadrant in which the tooth is located, depending upon its position. This system is common for charting in orthodontics.

Anatomic Features of the Teeth

Teeth should have contours, contacts, and embrasures. Contours of the teeth refer to the curving of the tooth. This can be either concave (curved inward) or convex (curved outward). Contacts are the areas where two surfaces of the teeth touch, which is also referred to as interproximal. Embrasures are the V-shaped space just below or just above the contact points of two teeth.

Tooth Morphology

Tooth morphology is the study of the shape of teeth.

Anterior Permanent Dentition

The anterior teeth have a distinct shape. They are generally smaller than the posterior teeth, have a straight flat edge, and have concave lingual surfaces. These teeth are designed and shaped in this manner to aid in the process of chewing and swallowing food. Anterior teeth also provide the patient with an esthetically pleasing smile.

Posterior Permanent Dentition

The posterior teeth are the powerhouse teeth in the mouth. They are generally larger in size than the anterior teeth; have wide chewing surfaces with pits, fissures, and grooves; and are multi-rooted. These teeth are designed and shaped in this manner to prepare food for being swallowed and digested.

Primary Dentition

The primary dentition consists of 20 “baby” teeth. These teeth are the incisors, the cuspids, and the molars. Children do not have premolars or bicuspids. These teeth erupt when the primary, or baby, first molar is lost. These teeth are usually not very large and are similarly shaped to those in the permanent dentition.

Oral Embryology and Histology

Oral embryology is the study of the prenatal development of the oral cavity. Histology is the study of the function and structure of tissues.

Oral Embryology

Oral embryology is the study of prenatal oral development, from zygote to embryo to fetus.

Prenatal Development

Preimplantation: This stage occurs the week following fertilization. The ovum implants itself, and the cells begin to multiply to begin forming body systems. The teeth are one of the first structures to begin formation.

Embryonic: This stage occurs from week two to week eight of the pregnancy. At about six weeks, the teeth begin to form at a more consistent rate. The zygote is now called an embryo.

Fetal: This stage occurs from week nine to birth, at approximately 40 weeks. The teeth continue to develop and form through gestation.

Life Cycle of a Tooth

Every tooth passes through stages of growth. The bud, cap, and bell stages are the growth periods of a tooth. Teeth grow very similarly to the way a baby grows. They are contained in a sac and continue to move through the growth periods prior to eruption.

Oral Histology

Oral histology is the study of the function and structure of the teeth as well as the tissues surrounding them. Each tooth consists of a crown and root. The surrounding tissues are called the periodontium and support the tooth in its socket.

Layers of the Tooth

Teeth have three layers. The first layer is the enamel. This is a protective layer that is stronger than bone. Enamel is the hardest structure in the body. The second layer is the dentin. Dentin is softer than enamel and will decay very rapidly. Dentin is the only layer of the tooth that can regenerate, or rebuild, itself, known as secondary dentin. The third layer of the tooth is the pulp. The pulp is the “heart” of the tooth. It supplies oxygen, blood, nutrients, and vitamins to the tooth. If the pulp becomes damaged or injured, it is possible that it will die or begin the process of dying. The tooth will need a root canal if this occurs.

Head and Neck Anatomy

A dental assistant should be knowledgeable in the anatomy of the head and neck. Bones, muscles, glands, nerves, and sinuses all play a role in dental health.

Bones of the Skull

The human skull is divided into the cranium and the face. The cranium consists of eight bones that protect the brain. The face has 14 bones.

Features of the Face and Neck

The face muscles are responsible for our facial expressions and play important roles in chewing, digestion, and speaking. Facial landmarks include the nostrils, known as anterior nares.

Salivary Glands

Saliva lubricates, cleans the mouth, and begins the digestion process. There are three major salivary glands and numerous minor salivary glands. The three major glands are the parotid salivary, the submandibular, and the sublingual.

Parotid Salivary Gland

  • It is located in the cheeks, just below the ears.
  • It is the largest of the three major salivary glands.
  • It secretes approximately 25% of the saliva in the mouth.
  • The Stensen’s duct delivers the saliva to the mouth from the gland.
  • The Stensen’s duct opens on the buccal surface of the maxillary first molars.

Submandibular Salivary Gland

  • It is the size of a walnut, located in the deep floor of the mouth.
  • It secretes approximately 60% of the saliva in the mouth.
  • The Wharton’s duct delivers saliva to the oral cavity.

Sublingual Salivary Gland

  • It is located in the floor of the mouth just under the tongue.
  • It is the smallest of the three major salivary glands.
  • It provides approximately 10% of the saliva in the mouth.
  • The Bartholin’s duct delivers saliva to the oral cavity.
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