Outcome 4 - Orthodontics Flashcards
What is Orthodontics?
The dental specialty involved with the evaluation and treatment of the dentition in order to maintain a functional relationship of the dental arches and teeth to the supportive tissues of the face and skull.
The 4 goals of orthodontic treatment are:
- To establish or maintain as nearly as possible, a normal, functioning occlusion
- To improve facial esthetics where they are affected by the teeth
- To eliminate any factor that might interfere with the growth and development of the maxilla and mandible
- To work with all other specialties in the rehabilitation of oral facial deformities
How are the goals of ortho achieved?
Acheived through the mechanical movement of teeth and jaws, or by influencing the natural movement of the teeth and the growth of the jaws.
What happens when force is applied to a tooth?
Without intervention by treatment, the tooth will move and changes will occur in the bone surrounding the root. This is how natural changes in tooth alignment may occur. The force in this case is usually from occlusion and the natural mesial force applied towards the midline due to the Curve of Spee
What does mechanical movement of teeth facilitate?
Facilitates bone resorption on the aspect of the socket that is receiving pressure, and bone deposition on the opposite aspect. These changes result in a remodeling of the alveolar bone.
What is the principle of mechanical movement?
To apply force for a specific period of time causing compression on one side of the periodontal membrane surrounding the root of the tooth.
The cells of the periodontal membrane will differentiate rapidly into osteoclasts (bone resorbing cells). This process will occur within 48-72 hours. Osteoclastic activity removes the cells from the bone on the alveolar side of the periodontal membrane.
What happens on the tension side of the tooth?
The tension causes the osteoblasts (bone- forming cells) to become activated, resulting in the development of new bone cells. As the tooth is held in place, the osteoblasts fill in the void on the tension side and the tooth is repositioned permanently.
What are developmental causes?
disturbances in dental development
Examples of developmental causes leading to malocclusion
Congenitally missing teeth
Malformed teeth – larger or smaller than usual
Supernumerary teeth
Ectopic eruption – eruption away from the normal position
What are Genetic Causes?
Inherited traits
What are inherited traits effecting occlusion?
Jaw size and tooth size are inherited – large teeth and small jaws affect development
Examples of Environmental Causes affecting occlusion?
Birth defects such as fetal molding
Birth trauma (injury can occur to the maxilla or mandible in a forceps delivery)
Injuries through developmental years:
Trauma to primary teeth may damage permanent tooth buds
Premature loss of primary teeth may allow movement of other teeth
Direct injury to permanent teeth may influence growth of dental arches
What is fetal molding?
(pressure from body position in utero can influence and distort development)
What are functional causes?
Oral habits can place pressure on the dental arches and facial bones, influencing their growth and development.
Examples of functional causes affecting occlusion?
Thumb-sucking
Tongue thrust swallow
Initial information collected at ortho appointment
-medical and dental history
-physical growth evaluation
- social and behavioural evaluation
Clinical evaluation information for ortho includes
-facial esthetics evaluation
-oral health examinations
-occlusal and functional evaluation
Diagnostic Records (for ortho) includes..
Photographs
Diagnostic Casts
Radiographs
Cephalometric Analysis
What type of photographs are taken at ortho appointment?
Both frontal and profile extraoral photographs are taken. Three intraoral photographs are also taken showing the maxillary teeth alone, the mandibular teeth alone and both arches as the mouth is opened to the maximum width.
What are diagnostic casts used for ortho?
The casts are used to assist the orthodontist in completing measurements and for the case presentation.
How are radiographs used for ortho appointment?
An extra-oral cephalometric radiograph is taken to evaluate the anatomic bases for malocclusion, skull, bones and soft tissue. It is retaken periodically throughout the treatment to study changes in jaw and tooth positions, and to evaluate growth.
What is Cephalometic Analysis?
After careful examination of the film to observe the relationship of hard and soft tissues, a tracing is made. A thin plastic sheet with a matte finish (on one surface) is taped down to the film and then to the view box with the matte surface facing up. Masking tape is satisfactory. The tape is placed only on the superior edge of the plastic sheet, so that one could lift up the sheet to examine the film in order to identify more obscure regions. The film should project about ¼ inch beyond the plastic sheet so that the tape can also hold the film. Sometimes it is useful to block the light emitted by the view box beyond the edge of the film. Outlines of the skeletal structures are then traced on the sheet with a sharp pencil.
3 Categories of Othodontic Appliances:
Active appliances
Functional appliances
Passive appliances
What are Active Appliances?
Active appliances can be used to move teeth in order to regain space. They are most often used when a tooth is prematurely lost and the adjacent teeth have tipped or moved into the space. A distinguishing feature of these appliances is some type of force being exerted to push or pull teeth into position. There are certain types of orthodontic problems that are caused by the lack of enough bone growth to accommodate the teeth. Active appliances can be used to widen the palate using a palatal expansion device, or to lengthen the mandible using a mandibular expander.
What are functional appliances?
Functional appliances use the muscle action of the patient to achieve the desired results. They are often used before fixed appliances to reduce any existing discrepancy between the upper and lower jaws. Headgear is a type of functional appliance that uses a combination of pushing and pulling forces to change the position of the mandible or maxilla.
What are Passive Appliances?
Passive appliances are used to maintain space or to retain teeth in their corrected position after orthodontic treatment is completed.
The most common retention appliances include..
the positioner, the Hawley retainer and the lingual retainer
What is an orthodontic positioner?
is made of rubber or acrylic and fits over both the upper and lower teeth. It is designed to do the following:
Retain the teeth in their desired position
Permit the alveolus to rebuild support around the teeth before the retainer is introduced
Massage the gingiva
What is the Hawley retainer?
is one of the most commonly-used retention devices in orthodontics. It is made of acrylic and wire and worn either on the maxilla or the mandible.
What is a lingual retainer?
The stabilization of the anterior teeth is often sufficient to prevent the relapse of the teeth after orthodontic treatment. If this is the case, a lingual retainer (a light steel wire) can be bonded from cuspid to cuspid. Composite resin is used to hold the bar in place. These retainers are often left in place for years to ensure complete bone deposition and maximum bone density.
What are Bands?
Metallic attachments that surround and are cemented to teeth, and serve as a means of anchoring wires or elastics
What are Brackets?
Brackets are welded or soldered to the band or may be bonded directly onto the tooth to secure the arch wire
What is an Arch wire?
The main piece of framework; arch wires are attached to bands and pass around the entire dental arch on either the lingual or labial surface, providing the pattern to which the teeth are moved
What is a Buccal tube?
Attachments that secure the ends of the arch wire to the molar bands
What are Elastic Ligatures?
Tiny elastic circles used to secure the arch wire to the brackets and exert a force causing teeth to be moved toward the arch wire
What are Ligature Wires?
Fine wires used in place of elastic ligatures to secure the main arch wire to the brackets and to apply pressure to the teeth to facilitate their movement toward the arch wire
What are Separating Wires/Springs?
Soft wire tied around the contact area of two adjacent teeth and twisted tight to create a force that moves the teeth slightly apart
Skills an orthodontic assistant can perfrom:
- Place and remove orthodontic spearators
- select, fit and cement orthodontic bands
- insert orthodontic appliances
- place and bond orthodontic brackets and bondable attachments
- insert, ligate and remove orthodontic arch wires, which were formed by a dentist, using individual elastomeric ligatures, chain elastomeric ligatures, wire ligature ties (separate and continuous) and self-ligation mechanisms
- trim and bend distal ends of orthodontic accessories
- place or remove orthodontic accessories
- remove orthodontic bands, brackets and bondable attachments with hand-held instruments
