Management Of Class 3 Malocclusion
Question 1. Classify etiology of malocclusion. Give the etiology and treatment of Angle’s Class 3 malocclusion.
Answer.
Class 3 Malocclusion
This malocclusion exhibit a class 3 molar relation with the mesiobuccal cusp of maxillary first permanent molar lies occluding in the interdental space between the mandibular 1st and 2nd molars.
Etiology of Angle’s Class 3 Malocclusion
Functional Factors
- Unfavorable anterior incisal guidance leads to class 3 malocclusion.
- If there is no treatment for functional cases, they become true class 3 malocclusion.
- Premature loss of deciduous molars can lead to mandibular displacement which leads to class 3 malocclusion.
- Loss of posterior teeth leads to loss of posterior proprioceptive support in habitual occlusion.
Read And Learn More: Orthodontics Question And Answers
Soft Tissue Factors
- Flat anteriorly positioned tongue which lies low in mouth leads to class 3 malocclusion.
- Lack in eruption of posterior teeth because of the lateral tongue thrust leads to the overclosure of mandible. This leads to autorotation which causes class 3 malocclusion.
Hereditary Factors
They leads to skeletal or True Class 3 malocclusion.
Racial
Class 3 malocclusion is common in some races. e.g. Every individual in German Royal family has Habsburg jaw.
Treatment of Class 3 Malocclusion
Class 3 malocclusion should be recognized treated early due to:
- Severity of malocclusion can be decreased by intercepting abnormal skeletal growth pattern.
- Anterior crossbite results in retarded growth of maxilla due to locking of maxilla within the mandible.
- If not treated early mandible continues to grow forward and worsens prenormally.
Treatment of Class 3 Malocclusion
Objectives
- In skeletal cases growth modulation should be achieved.
- In relieving crowding and correction of alignment of teeth.
- Incisor relationship should be corrected.
- Anteroposterior as well as unilateral crossbite is corrected.
- Molar relationship should be stabilized.
Skeletal Class 3 Malocclusion in Developing Child (Growing Child)
- In cases with midface deficiency in children functional appliances should be given in deciduous or mixed dentition.
- In functional appliances FR 3 is commonly used.
- In maxillary deficiency reverse pull headgears are indicated.
- In cases with prognathic mandible extraoral appliance like chin cup is advocated as early form of treatment.
- In cases with combined retrognathic maxilla and prognathic mandible reverse pull headgear or FR 3 with chin cup is used.
Treatment of Anterior Crossbite
Lower inclined plane or removable appliances incorporating the screws designed for the anterior expansion is used to treat mild anterior crossbite.
Treatment of Posterior Crossbite
It is treated by rapid maxillary expansion.
Role of Extractions
- Class 3 malocclusion is characterized by lower arch length deficiency and anterior crossbite can be treated by extracting mandibular fist premolars followed by fixed appliances
- First premolars should be extracted in both maxillary and mandibular arches, in case of arch length deficiency both the arches are involved.
Skeletal Class 3 Malocclusion in an Adult (After Growth)
- Camouflage is attempted in mild skeletal class 3 cases.
- For achieving good occlusion mandibular premolars should be extracted and class 3 elastics and chin cup is given.
- In camouflage retraction of mandibular molars makes chin prominent which is a drawback.
- In class 3 camouflage extraction of maxillary second premolars and mandibular fist premolar can be done which is followed by class 3 intermaxillary elastics which causes mandibular incisor retraction as well as molar correction.
- Surgical management can be done by maxillary advancement and by mandible push back.
- Sometimes a combination of upper and lower jaw surgery is done with reduction genioplasty.
Treatment of Pseudo Class 3/Function Class 3/Postural Class 3
- In early treatment occlusal equilibration is carried out.
- In late treatment correction of anterior crossbite is done.
Dentoalveolar Correction
- If one or two incisors are in crossbite removable appliances are used. Appliances used as anterior expansion plate and Z spring.
- Fixed appliances can also be used. Cases are treated either by extraction or non-extraction.
Question 2. What are the different possible combination of class 3 malocclusion? Write probable etiological factors for development of class 3 malocclusion.
Answer.
Possible combination of Class 3 malocclusion
- Class 3 Molar relation: Mesiobuccal cusp of maxillary first permanent molar occlude with interdental space between mandibular first and second permanent molars.
- Class 3 Canine relation: Maxillary canine occludes with interdental space between mandibular fist and second premolars.
- Class 3 subdivision: In this class 3 molar relation is present over one side with normal molar relation to other side.
- True Class 3: It is a skeletal malocclusion. Causes are prognathic mandible, retrognathic maxilla, combination of both
- Pseudo Class 3:
- It occurs because of occlusal prematurities, when the mandible moves from rest to occlusion, it slide forward into pseudo class 3 malocclusion.
- In rest position patient show normal molar relationship.
- In centric relation, such patients show Class 3 relationship.
Question 3. Discuss various methods of studying growth. What are the diagnostic methods you will use to predict class 3 growing malocclusion?
Answer. The following are the two major approaches of studying growth.
- Measurement approach
- Experimental approach.
Measurement Approach
This approach includes techniques that measure certain criteria on living animals/skeletal remains. These techniques are not invasive. Most growth studies on humans are conducted by measurement techniques.
Various measurement techniques can be used on living individuals or the skeletal remains including:
- Craniometry
- Anthropometry
- Cephalometric radiography
- Arcial growth
- Logarithmic spiral
- Finite element analysis.
Craniometry
This is the study of shape and form of human head and the skull. This was a measurement approach to study the growth and was one of the earliest approaches in anthropology. This was used to study the skulls which are found in human skeletal remains. So practice of craniometry consists of precise measurements by using landmarks on the skull. Skull is not the single bone and is made by various interlocked plates. Areas where such bones meet are easily identified and such places form major landmarks on the skull. Distances between various points can be measured and form the base of craniometry. So, in this manner structural model of skull which consists of angles and length between landmarks can be formed and so it is possible to compare one skull with another. Main advantage of craniometry is ability for the precise measurements which can be done on dry skulls. Only cross sections studies can be applied by craniometry.
Anthropometry
It refers to the measurement of a human individual. This is the early tool of physical anthropology and is used to identify and understand the human physical variation and also to correlate with physical and racial psychological traits. Anthropometry consists of systemic measurement of physical properties of human body mainly dimensional descriptors of both the size and shape of the body. Anthropometry uses various landmarks which are used in the study of dry skulls and are measured in the living individuals simply by using the sof tissue points overlying such bony landmarks. Anthropometry can follow the growth of an individual directly and make same measurements repeatedly at different times. This study produces longitudinal data.
Cephalometric Radiography
This technique has contributed majorly in our study of growth and development before it became a routine practice to use the cephalogram for orthodontic diagnosis and planning. Standard cephalometric points are noted on serial radiographs of individuals and compared to analyze the growth changes occurring.
Experimental Approach
This approach includes techniques that may be manipulative and invasive in nature and thus may harm the animal. Such studies are carried out on experimental animals. Experimental methods of study growth include the following:
- Vital staining
- Radioisotopes
- Autoradiography
- Implant radiography.
Vital Staining
- Certain vital stains can be used to determine the sequence and amount of new bone formation as well as specific locations of bone growth by utilizing histologic sections.
- The method involves injecting the dyes that stain the mineralizing tissues.
- These stains get incorporated into the bones and teeth and thus allow the study of changes in bones and teeth.
- Experimental animals are then sacrificed and the mineralizing tissues are studied histologically.
- By this method, detailed analysis of site, amount and rate of growth can be elicited.
- However, this does not allow longitudinal study. Repeated data of the same individual over time cannot be obtained.
- Examples of stains are Alizarin S, procion, tetracycline, trypan blue and florochrome.
Radioisotopes
Radioactive elements can be injected into tissues of experimental animals which get incorporated into the developing bone. Bone growth can be studied tracking the radioactivity emitted by those radioisotopes. For example, calcium 45, technetium 33 (Ca 45, Tc 33).
Implant Radiography
- Bjork in 1969 introduced the use of implants to study the bone growth.
- It is an experimental method to study the physical bone growth.
Procedure
- This mainly involves the implanting of small bit of biologically inert alloys inside the growing bone.
- These act as radiographic reference points for the serial radiographic analysis.
- Metallic implants used to study growth are very small mainly 1.5mm in length and 0.5mm in diameter and they are made of tantalum metal.
- These are embedded in various areas of both maxilla and mandible to study growth of skull.
Sites of implants in maxilla and mandible
In maxilla
- In hard palate behind deciduous canines.
- Below the anterior nasal spine
- Two implants on either side of zygomatic process of maxilla
- Border between the hard palate and alveolar process medial to fist molar.
In mandible
- At anterior aspect of symphysis, at midline below tip of roots.
- Two pins over the right side of body of mandible. One pin under fist premolar and other below second premolar or first molar.
- One pin at external aspect of right ramus of mandible at level of the occlusal surface of molars.
Following are the Diagnostic Methods to Predict Class 3 Growing Malocclusion:
Model analysis: In model analysis arch length discrepancy is seen.
Functional analysis: In functional analysis aberrations are reported in the normal functions such as respiration, swallowing, etc.
Cephalometrical analysis: In cephalometrical analysis following features are seen.
Question 4. Define Angle’s class 3 malocclusion. Differentiate between true and pseudo class 3 and write in detail the clinical features of class 3.
Or
Write difference between true and pseudo class 3.
Or
Differentiate between briefly true and pseudo class 3 malocclusion
Or
Write about clinical features of Angle’s Class 3 malocclusion.
Answer. It is defied as “a class 3 molar relationship refers to a condition where the mesiobuccal cusp of upper fist permanent molar occludes between the mandibular first and second molars”.
Difference Between True and Pseudo Class 3 Malocclusion
Clinical Features/Clinical Picture of Class 3 Malocclusion
Following are the clinical features of class 3 malocclusion
Occlusal Features
- Molar relation is class 3, i.e. mesiobuccal cusp of upper first permanent molar occludes between the mandibular first and second molars.
- Canine relation is class 3, i.e. maxillary canine occludes in between mandibular fist and second premolars.
- Incisor relationship is class 3 with reverse overjet.
- Due to transverse relationship of arches posterior crossbite is seen.
- Maxillary arch is frequently narrow while the mandibular arch is broad. Posterior crossbite is a common feature.
- Maxillary teeth are crowded as arch is narrow and short in some cases.
- As chin is prominent, patient has concave profie.
- Vertical growers exhibit increased inter-maxillary height and may have an anterior open bite. In some patients deep overbite can be seen.
Skeletal Features
- Maxilla is retrognathic.
- Mandible is prognathic.
- Combination of prognathic mandible and retrognathic maxilla is seen.
- Incisor, canine and molar relations are class 3
- Mentolabial sulcus is shallow.
- Chin is prominent.
- Lower facial height is increased.
Soft Tissue Features
- Facial profile is concave.
- Anterior facial divergence is present.
- Lips are incompetent.
- Short upper lip
- Tongue is anteriorly placed.
Functional Features
- Mandible is displaced forwardly.
- As there is unilateral crossbite, lateral mandibular displacement is present.
- In pseudo Class 3, patients have skeletal class 1 pattern, this abnormality is due to tilting of teeth and due to forward path of closure.
Growth
- Unfavorable facial growth is seen in Class 3 cases
- Tendency to open bite increases with vertical facial growth.
- Excessive horizontal growth gets worse with reverse overjet.
Question 5. How will you manage a case of developing class 3 malocclusion.
Answer.
Management of a Case of Developing Class 3 Malocclusion
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