An orthodontist must undertake at least two additional years of formal education in an accredited university after obtaining a dental degree. To become a board-certified orthodontist, he or she must pass an examination by the American Association of Orthodontists. In some states the expanded-function dental assistant is allowed to perform many of the tasks involved, such as sizing and placing bands and placing ligature ties and separators.
Malocclusion is occlusion that deviates from a class I normal occlusion as a result of irregularities, such as those in the positions of teeth and bite relationships. What causes or influences malocclusion?
Interruption or absence of tooth bud formation results in congenitally missing teeth. What are malformed teeth? What are supernumerary teeth? What is an ectopic eruption?
Genetic: The patient usually presents with a small jaw from one parent and larger teeth from the other parent or with congenitally missing teeth. What is fetal molding?
The orthodontist corrects oral habits that cause malalignment. Thumb and finger sucking beyond age 5 will affect facial structure development and growth. What is bruxism?
In 1899, Dr. Edward Angle introduced a classification of malocclusion based on the relationship of the maxillary and mandibular first permanent molars. What is this system known as? (The Angle classification of malocclusion . )
Class I malocculsion is also known as neutroclusion. The facial profile is known as mesognathic. What should be used as a guide if one or both of the first molars are missing from the side that is being classified?
The facial profile is known as retrognathic. The maxilla protrudes. The lower lip is full and often rests between the maxillary and mandibular incisors. The mandible appears retruded or weak.
Molar relation: The buccal groove of the mandibular first molar is distal to the mesiobuccal cusp of the maxillary first molar by at least the width of one premolar. Canine relation: The distal surface of the mandibular canine is distal to the mesial surface of the maxillary canine by at least the width of one premolar.
The facial profile is known as prognathic. The lower lip and mandible are prominent.
Molar relation: The buccal groove of the mandibular first molar is mesial to the mesiobuccal cusp of the maxillary first permanent molar by at least the width of one premolar. Canine relation: The distal surface of the mandibular canine is mesial to the mesial surface of the maxillary canine by at least the width of a premolar.
Crowding or overlapping makes oral hygiene (brushing and flossing) more of a challenge for the patient. Overjet is the horizontal distance between the labioincisal surfaces on the mandibular incisors and the linguoincisal surfaces of the maxillary incisors. What instrument would you use to measure an overjet? (Probe.)
Overbite is the vertical distance by which the maxillary incisors overlap the mandibular incisors. It has three classifications: normal, moderate, and deep/severe. Crossbites occur when the maxillary or mandibular teeth are either facial or lingual to their normal position. What is the condition called when the mandibular anterior teeth are occluded anteriorly or facially to the maxillary anterior teeth? (Underjet.)
Severe malocclusion and dental facial deformities can be a social handicap. Oral function is influenced when malocclusion compromises chewing, jaw movement, speech, and temporomandibular joint function. What could be affected if the oral-function needs of the patient are not fulfilled? What could be affected if the need to have a healthy and sound dentition is not achieved?
Corrective orthodontics includes fixed appliances, removable appliances, and orthognathic surgery.
What might the medical and dental history reveal about a patient’s orthodontic condition or needs? Why is an evaluation of physical growth necessary? Why is a social and behavioral evaluation necessary? Clinical evaluation includes evaluation of facial aesthetics, oral health, and jaw and occlusal function.
Facial symmetry is assessed, including frontal and profile evaluations. The jaw and the occlusal relationship between the teeth and jaws are key to determining an orthodontic treatment and strategies. Functional characteristics of the jaws are also inspected. Lateral or anterior shifts of the mandible on closure are of special interest.
Two standard extraoral photographs are taken: frontal view and profile view. Three standard intraoral photographs are required: full direct view, maxillary occlusal view, and right buccal view.
The photo on the left is the profile view. The photo on the right is the frontal view. What visual aspects are noted on these photographs? ( Jaw size, jaw shape, and jaw symmetry.)
A, Front view shows the relationship between the anterior teeth including the overjet, overbite, and whether an open bite exists. B, Occlusal view of the maxillary arch shows crowding and or overlapping, occlusal wear, and malalignment of teeth. C, Right buccal view shows crossbites, openbites, and molar and canine relationship.
The cephalometric radiograph is the most commonly used radiograph in orthodontic evaluation. The analysis of the radiograph is completed by the marking of cephalometric landmarks at a series of points to determine skull size and shape. These measurements reveal skull-growth patterns, which will determine the type of orthodontic treatment.
The cephalometric radiograph is a profile or lateral view. It is taken at different intervals: before, during, and after orthodontic treatment. The radiographs can be superimposed over each other to demonstrate jaw growth.
Diagnostic models are also called study models. Diagnostic models are used for the diagnosis and case presentation of the orthodontic patient. Diagnostic models are made from plaster after an alginate impression of the patient’s mouth is taken. Models are often fabricated before orthodontic treatment and again after it is completed.
Numerous intraoral instruments are used, including orthodonic scalers, ligature directors, the band plugger and bite stick, bracket-placement tweezers, and pliers. The ligature director is used with a push stroke to place the ligature where it is needed around brackets and bands.
The band plugger is the instrument used to seat molar brackets. This instrument is important because bands fit snugly and would be difficult to seat by simply pressing them down with a finger. The bite stick is also helpful in the seating of bands. The patient occludes on the bite stick, which also helps seat the snugly fitting molar bands through the gentle use of occlusal forces.
Care must be taken in the sterilization of hinged instruments such as the bracket tweezer. What is the most common result when hinged instruments are sterilized incorrectly? (Corrosion or rust around the hinged area. )
Bird-beak pliers are used to bend wires for both removable and fixed appliances. Contouring pliers have a bent beak. The bent beak aids in the placement of molar and posterior bands. What are Weingart utility pliers?
Pin and ligature cutters are used to cut the ligature wire once it has been ligated around the bracket. Howe (110) pliers are versatile because of their design. They have a round, flat, wide tip, making them suitable for holding orthodontic materials and appliances intraorally.
Wire-bending pliers have notched areas throughout the beak to make it easier to bend wire while holding the wire securely in the pliers. Ligature-tying pliers have finely serrated narrow beaks for ease in ligature tying.
Fixed appliances are cemented to the teeth and cannot be removed by the patient. Auxiliaries, such as hooks and tubes, are also attached to brackets and bands. The arch wire is attached to all brackets and exerts opposing forces on the teeth to cause them to move.
Can you name the pieces of the fixed appliances shown on this slide? What will become an increased challenge to this patient on a daily basis?
The sequence of events in the orthodontic treatment plan may vary slightly from patient to patient. After the data have been collected, diagnostic records have been assembled, and clinical evaluation is complete, the orthodontist will outline the treatment sequence, including how and when the orthodontic appliances will be placed in the patient’s mouth and later removed.
How do you place the separator? Who places the separator? How do you remove the separator? Who removes the separator?
How is an orthodontic band placed? Who places the band?
Orthodontic bands come in a variety of sizes. Bands are most commonly placed on molars. The occlusal aspect of the band is slightly rolled or contoured. The gingival aspect of the band is straight and smooth.
The bonded bracket is the most common type of attachment for fixed appliances. Brackets are placed in a number of ways, depending on the teeth in question.
Brackets vary in size according to the teeth to which they will be bonded. Notice the four tie wings on each of the brackets. What is the purpose of the tie wings?
Headgear is usually a removable appliance inserted and removed by the patient as recommended by the orthodontist. Edgewise tubes are an integral part of contemporary orthodontic procedures. Edgewise tubes are rectangular and hold the arch wire securely.
In addition to the use of arch wires and ligatures to provide forces to encourage teeth movement, elastics are used. Elastics extend to and from various hooks attached to the facial surfaces of bands and brackets.
The arch wire fits into a horizontal slot in the brackets or slides into the buccal tubes on molar teeth. Arch wires come in a variety of diameters, which affect the magnitude of the force that is applied to the teeth.
Nickel-titanium wire is used during initial stages of tooth movement for malaligned or crowded teeth. Stainless-steel wire is used to apply more force and give better stability to control the teeth. It can withstand greater forces and is known as the working arch wire. Optiflex wire is a newer type of arch wire made from composite materials with a top coating of optical-glass fibers.
The shape of the arch wire used is determined by the treatment and movement needed during each stage of the orthodontic procedures. The shape of the arch wire is also determined by the current phase of the treatment.
Arch wires are anchored into the brackets by ligature ties. Ligature ties may be made of thin wire or tiny elastic bands. The orthodontist may assign individual brackets to be tied with individual ligatures or an entire quadrant or sextant tied with one ligature.
Elastic ties are also used to secure the arch wire to the brackets. Young patients like the elastic ties because they come in a variety of colors.
Power products are accessory items made of elastic materials that aid tooth movement. These power products are attached to the fixed appliances by being placed over the brackets or attached to labial hooks or lingual arch attachments.
It is important to avoid using power products containing latex materials because of the increased incidence of latex sensitivity among operators, dental assistants, and patients. Instruments used to place elastic power products include the hemostat and orthodontic scaler.
Headgear is composed of two parts: (1) The facebow is inserted into headgear tubes, which are attached to the buccal aspect of molar orthodontic bands. (2) The traction device may be one of a variety of styles, depending on the force needed to move the maxillary arch.
Upper left: Chin-cap traction device is a combination of a high-pull strap and chin cup to help control the growth of the mandible in patients with class III malocclusion. Lower right: The combination headgear traction device is a combination of a high-pull and a cervical-traction device. It exerts a force along the occlusal plane and upward. What is the headgear in the upper right image? What is the headgear in the lower left image?
The biggest day-to-day challenge faced by a patient with full-mouth fixed orthodontic appliances is plaque control and maintenance of a healthy mouth. Orthodontic appliances offer areas for food and plaque to be trapped and hidden. What will result from poor oral hygiene?
Besides good oral-hygiene habits, the orthodontic patient must also develop good eating habits. Healthy foods and good eating habits will help maintain healthy teeth and gingiva and will also prevent damage to the orthodontic appliances.
After removal of the fixed appliances, the orthodontic treatment is not complete. The orthodontic positioner is a custom-made appliance constructed of rubber or pliable acrylic that fits over the patient’s dentition after orthodontic therapy.
The Hawley retainer is the most commonly used removable retainer. The Hawley retainer is made of a clear self-polymerizing acrylic that is designed to hold wire clasps on molar teeth.