Orthodontic Diagnosis
Question 1. Enumerate diagnostic aid. Discuss any two in detail.
Or
Write short note on essential diagnostic aids.
Answer.
Diagnostic Aids
Essential Diagnostic Aids
- Case selection
- Clinical examination
- Study models
- Certain radiographs:
- Periapical radiograph
- Bitewing
- Panoramic.
- Facial photographs
Read And Learn More: Orthodontics Question And Answers
Nonessential or Supplemental Diagnostic Aids
- Specialized radiographs:
- Cephalometric radiographs
- Occlusal intraoral films
- Selected lateral jaw view
- Cone shift technique.
- Electromyographic examination of muscle activity.
- Hand and wrist radiographs to assess bone age.
- Endocrine tests.
- Estimation of basal metabolic rate.
- Diagnostic set-up.
- Occlusograms
- Sensitivity (Vitality) test
- Biopsy.
Essential Diagnostic Aids
Following are the essential diagnostic aids
- Case history
- Clinical examination
- Study models
- Certain radiographs
- Periapical radiographs
- Bitewing
- Panoramic
- Facial photographs
Case History
It consists of information which is gathered from the patient and parent or guardian which aid in complete diagnosis of the case. Case history has various personal details, chief complaint, present and past dental as well as medical history and the associated family history.
Personal Details
- Name: Name of the patient should be recorded for communicating and identifiation the patient and also addressing patient by his/her name which has positive beneficial psychological effct on patient.
- Age: The chronological age of patient helps in both i.e. diagnosing and treatment planning. Various treatment protocols are directed by the age of patient such as growth modification by using functional and orthopedic appliances which are best to be done at growth period while surgical procedures are carried out aftr completion of growth.
- Sex: This is very important as the timing of growth is different in both males and females.
- Address and occupation: They are very useful in communication and evaluation of socioeconomic status of patient.
Chief Complaint
- This should be recorded in patient’s own words.
- It helps clinician to identify priorities and desires of patient which helps in settng the treatment objectives which can satisfy patient as well as their family.
Medical History
- Few of the medical conditions contraindicate use of orthodontic appliances.
- Some of the physical conditions need various precautionary measures to be taken before to or during orthodontic therapy. E.g. antibiotic coverage is required in patient with rheumatic fever or cardiac diseases.
Dental History
- Past dental history helps to assess the parent’s and parent’s atttude towards dental health as well as dental treatment.
- Dental history consists of information on age of eruption of deciduous and permanent teeth, history of extraction, decay restoration and trauma to dentition.
Prenatal and Postnatal History
- It consists of information on condition of the mother at the time of pregnancy and the type of delivery.
- Usage of certain teratogenic drugs such as thalidomide, some infections such as German measles at the time of pregnancy lead to congenital deformities of child.
- Forceps delivery leads to TMJ injuries and mandibular growth retardation.
- Postnatal history includes type of feeding, presence of habits.
Family History
This record the details of malocclusion which occur in other members of the family, which provide the clue of inherited conditions e.g. Skeletal Class II and Class III malocclusion, congenital conditions such as clef lip and clef palate.
Clinical Examination
It consists of following points:
- General examination
- Extraoral examination
- Intraoral examination
General Examination
It consists of general assessment of the patient and begins as soon as patient enters the clinic. It consists of
- Height and weight: Both height and weight of the patient should be noted. They give a clue to physical growth and maturation of patient which have dentofacial correlation.
- Gait: This is the manner in which patient walks. Abnormalities of the gate are associated with neuromuscular disorders which have dental correlation.
- Posture: It refers to the way a person stand. Abnormal postures predispose to malocclusion because of alteration in maxilla – mandibular relationship.
- Body built: Sheldon classifid it as:
- Ectomorphic: Tall and Thin physique
- Mesomorphic: Average physique
- Athletic: Short and obese physique
Extraoral Examination
Shape of head
- Mesocephalic: Average shape of head. They have normal arches.
- Dolichocephalic: Long and narrow head
- Brachycephalic: They have narrow dental arch, broad and short hand. They have broad dental arches.
Facial form
Scientific classification to classify face is:
- Mesoprosopic—It is an average or normal face form.
- Euryprosopic—Face is broad and short.
- Leptoprosopic—It is a long and narrow face form.
Assessment of facial symmetry
- For facial symmetry the examination is carried out in frontal and lateral views.
- In frontal plane intercanthal width is equal to width of nose.
- Proportionwise the ideal face is divided into central, medial and lateral equal fits. Nose and chin lies in center in central fit.
- In vertical plane the nasal length is one-third of the complete facial height.
- Nasal contour can be straight and convex.
- Vertical height of midface is equal to height of lower face.
- In lower face mouth is equal to one-third of the distance between nose and chin.
- Height of forehead is measured from hairline to glabella. Forehead is of two types, i.e. flt and steep.
- If face is normally balanced it consists of equal upper face height, middle face and lower facial height.
Facial profile
- Facial profile is examined by viewing the patient from the side.
- Facial profile helps in diagnosing gross deviations in the maxillomandibular relationship.
- The profile is assessed by two reference lines and three landmarks:
- Three landmarks are used which are: sof tissue nasion, nasion and sof tissue pogonion.
- Two reference lines are
- First line is dropped from sof tissue nasion to subnasale
- Second line is dropped from subnasale to soft tissue pogonion
- So, based on the relationship of two lines and the three landmarks the facial profie exists as:
- Straight profie: Two lines form a nearly straight line.
- Convex profile: Two lines form an angle with the concavity facing the tissue.
- Concave profie: Two reference lines form an angle with the convexity towards the tissue.
Facial divergence
Facial divergence is defied as an anterior or posterior inclination of the lower face relative to the forehead.
- Facial divergence can be of three types:
-
- Anterior divergent: A line drawn between the forehead and chin is inclined interiorly seen in class III cases.
- Posterior divergent: The line stands posterior towards chin seen in class II cases.
- Straight or orthognathic: The line between the forehead and chin is straight seen in class I cases.
- It uses two soft tissue landmarks, i.e. soft tissue nasion and soft tissue pogonion.
Examination of lips
- In a balanced face upper lip is protruded slightly in relation to lower lip.
- When upper lip is at rest the 2 mm of incisal edges of maxillary incisors is seen at rest.
- Lip should be examined for the habits such as lip thrust, lip competency, lip insuffiency, abnormal lip habits.
- Lip competency is confiured as:
- Competent lips: Lips are in slight contact when the musculature is relaxed.
- Incompetent lip: They are morphologically short lips which do not form a lip seal in a relaxed state.
- Potentially incompetent lips: They are normal lips that fail to form a lip seal due to proclaimed upper incisors.
- Everted lips: They are hypertrophied lips with weak muscular tonicity.
Nasolabial angle and incisor protrusion
- Nasolabial angle (NLA) is the angle which is formed by the tangent to base and to upper lip.
- Normal nasolabial angle is 110°.
- With proclination of maxillary incisors angle NLA decreases.
- With retroclination of maxillary incisors angle NLA increases.
Clinical Frankfort mandibular plane angle
- Inclination of mandibular plane angle to the Frankfort horizontal plane is measured.
- It is done by, over the patient’s face a scale is kept over Frankfort plane. Second scale is kept along the lower border of mandible.
- Area where the posterior parts of two scales meet should be recorded.
- If the posterior ends of angle meet behind auricle or in occiput it means angle is high.
- In cases with long face and open bite mandibular plane angle become steep.
- In cases with short faces and skeletal deep bite the mandibular plane angle become flt.
Examination of nose
It contributes to the aesthetic appearance of the face:
- Nose size: Normally the nose is one third of the total facial height.
- Nose contour: Shape of nose can be straight, convex or crooked due to nasal injuries.
- Nostrils: It is oval and bilaterally symmetrical.
Examination of chin
- Mentolabial sulcus: It is concavity seen below lower lip. Deep mentolabial sulcus is seen in Class II division 1 malocclusion but is shallow in bimaxillary protrusion.
- Mentalis activity: Normally mentalis muscle shows no contraction when at rest. Hyperactive mentalis is seen in Class II division 1 cases. It leads to puckering of chin.
- Chin position and prominence: Prominent chin is associated with Class III malocclusion while recessive chin is common in class II malocclusion.
Intraoral examination
- Mouth opening: Intraoral examination begins with measurement of the mouth opening. Normal mouth opening is 45 to 55 mm for adults and less than 45 mm for children.
- Tongue: Presence of excessively large tongue is indicated by presence of imprints of teeth over the lateral margin of tongue giving it a scalloped appearance. Patient whose tongue reaches till tip of nose has long tongue. Lingual frenum is examined for tongue tie.
- Palate: Following findings should be examined on palate:
- Variation present in palatal depth occurs in association with the variation of facial form. Dolichofacial patients have deep palate.
- Presence of swelling in the palate indicates an impacted tooth, presence of cysts or bony pathology.
- Mucosal ulceration and indentations are the features of traumatic deep bite.
- Presence of cleft in palate is associated with discontinuity of palate.
- Third palatal rugae is in the line with canines which help in assessment of maxillary anterior proclination.
- Gingiva: It is examined for inflmmation, recession and other mucogingival lesions.
- Frenal attchment: Due to thick maxillary labial frenum, midline diastema may arise. High attachment of mandibular labial frenum causes gingival recession.
- Tonsils and adenoids: Size and degree of inflammation of any of the tonsils should be examined. Abnormally inflamed tonsils causes alteration in tongue and the jaw posture, upsetting the orofacial balance causing malocclusion.
- Dentition: It should be examined and following details should be recorded:
- Teeth present inside the oral cavity.
- Unerupted teeth
- Missing teeth
- Status of dentition i.e. erupted and non-erupted tooth
- Presence of dental caries, restorations, malformations, hypoplasia, wear and discoloration
- Ask the patient to close the jaws in centric occlusion and determine the molar relation which is described as Angle’s Class I, II and III.
- Overjet and overbite are recorded. If any variation is present, it should be recorded.
- Transverse malrelations i.e. crossbite and shif in upper and lower midline should be looked.
- Individual tooth irregularities i.e. rotations, displacement, intrusion and extrusion are noted.
- Maxillary and mandibular arches are examined to study their arch form as well as symmetry.
Study Models
Study casts are essential diagnostic aids.
- Orthodontic study models are accurate plaster reproduction of the teeth and their surrounding soft tissues.
- Study models are three dimensional view of the maxillary and mandibular dental arches.
Ideal requisite of study model
- Models should accurately reproduce the teeth and their surrounding sof tissue without any distortion.
- Models are to be trimmed in such a manner that they are symmetrical and pleasing to the eye. This enables instant identifiation of asymmetries in the arch form.
- Models are to be trimmed in such a way that when replaced on their backs, they accurately reproduce the occlusion.
- Study model should have a clean, smooth and nodule free surface.
- Study models should not only depict the teeth but should also reproduce as much of the alveolar process as possible.
Use of study models
- They enable the study of occlusion from all aspect.
- They enable accurate measurement to be made in a dental arch. They help in measurement of arch length, arch width and tooth size.
- They help in assessment of treatment progress by dentist as well as the patient.
- They help in assessing the nature and severity of malocclusion.
- They are helpful in motivation of the patient and to explain the treatment plan as well as progress to the patient and parents.
- Study models make possible to stimulate treatment procedure on the cast such as mock surgery.
- Study models are useful to transfer records in case the patient is to be treated by another clinician.
Parts of a study model
- Anatomic portion
- Artistic portion.
- Anatomic portion: The anatomic portion is that part of the study model which is the actual impression of the dental arch and its surrounding structures. Anatomic portion is usually made of stone plaster.
- Artistic portion: This part consists of a plaster base that supports the anatomic portion.
Question 2. Write short note on facial profile.
Answer.
Facial profile is examined by viewing the patient from the side.
- Facial profie helps in diagnosing gross deviations in the maxillomandibular relationship.
- The profie is assessed by two reference lines and three landmarks:
- Three landmarks are used which are soft tissue nasion, nasion and sof tissue pogonion.
- Two reference lines are
- First line is dropped from soft tissue nasion to subnasale
- Second line is dropped from subnasale to sof tissue pogonion
- So, based on the relationship of two lines and the three landmarks the facial profile exists as:
- Straight profile: Two lines form a nearly straight line.
- Convex profile: Two lines form an angle with the concavity facing the tissue.
- Concave profie: Two reference lines form an angle with the convexity towards the tissue.
Question 3. Classify diagnostic aids used in orthodontics and discuss in detail about nonessential diagnostic aids.
Answer.
Classification of Diagnostic Aids:
Essential Diagnostic Aids
- Case history
- Clinical examination
- Study models
- Certain radiographs:
- Periapical radiograph
- Bitewing
- Panoramic.
- Facial photographs.
Nonessential or Supplement Diagnostic Aids
- Specialized radiographs:
- Cephalometric radiographs:
- Lateral cephalometric radiographs.
- Frontal cephalometric radiographs.
- Oblique cephalometric radiographs.
- Occlusal radiographs.
- Selected lateral jaw view.
- Cone shift technique.
- Cephalometric radiographs:
- Electromyographic examination of muscle activity.
- Hand and wrist radiographs to assess bone age.
- Endocrine tests.
- Occlusograms.
- Estimation of basal metabolic rate.
- Diagnostic set-up.
Nonessential Diagnostic Aids
Radiographs: They are the valuable tool in establishing the orthodontic diagnosis.
Occlusal Radiograph
- They are advantageous to patient who have restricted mouth opening for IOPAs.
- A large segment of dental arch is viewed in these radiographs including palate and dental arch.
- UsesFor location of impacted and supernumerary teeth.
- For studying of arch expansion procedures
- For diagnosing presence or absence of fractures.
- For locating foreign bodies in jaws and stones in salivary duct.
Extraoral Radiographs
These radiographs enable viewing of orofacial region with placement of the fim extraorally.
Panoramic Radiographs
They enable viewing of maxillary and mandibular arches with supporting structures.
Uses
- Shows ankylosed and impacted teeth.
- Useful in assessing mixed dentition.
- For studying path of eruption.
- For diagnosing pathologies, fractures and supernumerary teeth.
Advantages
- Broad anatomic area and landmarks are seen.
- Radiation exposure is low
- Can be used easily in cases which have restricted mouth opening.
Disadvantages
- Artifacts can occur.
- It is expensive.
- Inclination of anterior teeth is not visualized.
- Clarity of structures is less as compared to IOPAs.
Cephalometric Radiographs
- In this the head is held in predetermined position.
- These radiographs are used for comparison of serial radiographs.
- Types of cephalograms are frontal, lateral and oblique.
Advantages
- A broad anatomic area can be visualized.
- Patients radiation exposure is low.
- It helps in orthodontic diagnosis by enabling the study of skeletal, dental and sof tissue structures of craniofacial region.
- It helps in treatment planning.
- It helps in evaluation of the treatment results by quantifying the changes brought about by treatment.
- It helps in predicting the growth related changes.
- By cephalometries the skeletal and dental abnormalities can be classified.
Disadvantages
- Give 2 dimensional view of three dimensional object.
- Give a static picture, which does not take time into consideration.
- Reliability is not always accurate there can be errors in determining the landmarks.
- There are different methods of analyzing a cephalogram and so no standardization of analyze.
Hand-wrist Radiograph
Hand-wrist Radiograph is a Skeletal Maturity Indicator.
- There are numerous small bones in the hand-wrist region. They follow a pattrn in ossifiation and union of epiphysis with diaphysis.
- Carpal bones were fist named by Lyser in 1683.
- In hand-wrist radiographs left hand wrist is used and a PA view is taken for hand-wrist region.
- Bjork divided the skeletal development in the hand-wrist area into 8 stages. These stages represent a particular level of skeletal maturity.
Indications of hand-wrist radiograph
- In cases with major discrepancies between chronological and dental age.
- In cases where prediction of pubertal growth spurt is required.
- In cases with skeletal Class 2 and Class 3 malocclusion before beginning their treatment so that their growth potential is assessed.
- For skeletal age assessment to study growth of an individual.
- Indicated in research studies to make out the effct of hereditary and environment on dentofacial growth.
- In patients with skeletal malocclusion and need orthognathic surgery.
Diagnostic set up
- Diagnostic set up was fist proposed by H.D. Kesling.
- Diagnostic set up is made from an extra set of trimmed and polished study models.
- Individual teeth and their associated alveolar processes are sectioned of and replaced on the model base in desired positions.
- Diagnostic set up thus helps in simulating various tooth movements which are planned for patients.
Procedure of diagnostic set up
- Cut the cast by using a Fretsaw blade to separate the individual teeth.
- A horizontal cut is made 3 mm apical to gingival margin.
- Vertical cuts are made to separate the individual teeth.
- The individual teeth are set in the desired position by using red wax.
Uses of diagnostic set up
- It is useful in visualizing and testing the effect of complex tooth movements and extractions on occlusion.
- Patient can be motivated by simulating the various corrective procedures on the cast.
- Tooth size: Arch length discrepancy can be visualized by means of a set up.
Occlusograms
An occlusogram is 1:1 reproduction of occlusal surfaces of plaster models on an acetate tracing paper. Upper tracing should be oriented to lower tracing by help of grooves cut in back side of plaster models.
Technique
- For making the occlusogram either the photostatic or photographic copies of both maxillary and mandibular study models is made.
- Copies should be placed parallel to occlusal plane.
- Tracing of teeth of mandibular and maxillary arches should be superimposed to match the occlusion.
Uses
- For estimation of arch length as well as width and predicting occlusal relationship.
- For estimation of spacing and crowding.
- For estimation of requirement of anchorage
- For analyzing tooth movement requirement in three planes of space.
- It permits clinician to make accurate and reliable arch length discrepancy measurements.
Electromyography
It is the procedure which is used to record the action potentials formed in voluntary muscles when they are excited. Here instrument used is electromyograph and the output is electromyography.
- Surface membrane of muscle cell is positively charged over external surface and negatively charged on internal surface. Action potential reverses charge on the muscle membrane. Now series of changes occur which bring the muscle contraction.
- Electromyograph measures amplitude, frequency and duration of action potential. Action potential is received, amplified and recorded.
- Recording of electrical charges from muscle is done by surface or needle electrodes.
- Surface electrode should be placed in skin overlying the muscle. It has superfiial activity
- Needle electrode should be placed in belly of muscle. It is invasive procedure and is used in deep muscles.
- Permanent paper record should be taken by pen writing device. Electromyogram is displayed by an oscilloscope.
Uses
- It is used to study role of musculature in craniofacial growth.
- It also shows activity of mandibular elevators and depressors.
- It studies the pronounced buccinator activity in class 2 division 1 malocclusion.
- It is used to assess the aberrant muscular activity which is associated with various habits.
Question 4. Define and classify diagnostic aids in orthodontics and discuss in detail the uses of OPG.
Answer. Diagnosis involves the development of a comprehensive and concise database of pertinent information which is sufficient to understand the patient’s problem as well as answer questions arising in the treating clinicians mind. The data is derived from diagnostic aids.
Classification of Diagnostic Aids
Essential diagnostic aids
- Case selection
- Clinical examination
- Study models
- Certain radiographs:
- Periapical radiograph
- Bitewing
- Panoramic.
- Facial photographs
Non-essential or supplemental diagnostic aids
- Specialized radiographs:
- Cephalometric radiographs
- Occlusal intraoral films
- Selected lateral jaw view
- Cone shif technique.
- Electromyographic examination of muscle activity.
- Hand and wrist radiographs to assess bone age.
- Endocrine tests.
- Estimation of basal metabolic rate.
- Diagnostic set-up.
- Occlusograms
- Sensitivity (Vitality) test
- Biopsy.
Uses of OPG
- As a substitute for full mouth intraoral periapical radiographs.
- For evaluation of developmental anomalies and TMJ dysfunction.
- For evaluation of tooth development for children, the mixed dentition and also the age.
- To assist and assess the patient for and during orthodontic treatment.
- To establish the site and size of lesions such as cysts, tumors and developmental anomalies in the body and ramus of the mandible.
- For follow-up of treatment, progress of pathology or postoperative bony healing.
- Prior to any surgical procedures such as extraction of impacted teeth, enucleation of cyst, etc.
- For detection of fractures of the middle third and the mandible aftr facial trauma.
- To study the antrum, especially to study the flor, posterior and anterior walls of the antrum.
- Periodontal disease as an overall view of the alveolar bone levels.
Question 5. Write short note on cusp of Carabelli.
Answer. This cusp was fist described by George Carabelli in 1842 and was named so.
- The Carabelli structure is a tubercle or cuspule, or a groove, often seen on the palatal surface of the mesiopalatal cusp of maxillary permanent molars.
- It includes a variety of expressions that range from complete absence to pits, grooves, tubercles, cusplet, or cusps.
- The cusp of Carabelli is a heritable feature. It has been proposed that homozygosity of a gene is responsible for a pronounced tubercle, whereas, the heterozygote show as slight grooves, pits, tubercles or bulge.
- Its greatest incidence is among the Caucasians.
- It represents the end product of the interaction of a complex system of ontogenetic and environmental factors.
- Carabelli trait is associated with increased caries prevalence.
- Its main clinical signifiance is that dentists are advised to perform a careful examination to the lingual surfaces of the maxillary fist molars to rule out the presence of the Carabelli structure and caries.
- The prefabricated molar bands that are commonly used by orthodontists have no compensation for cusp of Carabelli which results in loose fi. As a result the space which remains between the band and the tooth is filed by food debris and bacteria and it results in early caries and periodontal diseases.
Question 6. Write short note on Bird like facies.
Answer. Bird like facies is most commonly seen with Pierre Robin syndrome.
- This condition is due to a genetic defect, which gives rise to three problems, a very small lower jaw, a slit like hole in the palate of mouth, i.e. clef palate and the tongue appear to fall into the throat, i.e. retroglossoptosis.
- If the lower jaw is very small or retruded compared to the upper jaw, the patient has a ‘bird-face’ appearance. In such cases the upper front teeth appear to hang out of the mouth.
- A very small lower jaw is the most common fiding in Pierre Robin syndrome. But the growth of the mandible seems to normalize by the 5th year of life, it however gives a characteristic appearance called as “bird facies.”
- Speech defects are common in Pierre Robin syndrome because of the unusual highly placed position of the tongue and the lower jaw.
- In mild cases, the condition is self-resolving and no treatment except strict monitoring is necessary. However, in cases of severe airway blockage, mechanical intubation may be required. In life-threatening airway blockage, surgical intervention is necessary. The clef palate is treated conservatively or by surgical intervention depending on the extent of the cleft
Question 7. Write short note on diagnostic aids.
Answer. Comprehensive orthodontic diagnosis is established by use of certain clinical implements called diagnostic aids.
Essential Diagnostic Aids
- Case history: This involves eliciting all relevant information by direct questioning to patient or parent. It consists of major complaints, medical history, dental history, prenatal history, postnatal history, family history.
- Clinical examination: This is the prerequisite for correct assessment and interpretation of quantitative analysis which is obtained via various investigations. Goals of clinical examination are to evaluate and document facial, occlusal and functional problems.
- Study models: Orthodontic study models are accurate plaster reproduction of the teeth and their surrounding soft tissues. Study models are three-dimensional view of the maxillary and mandibular dental arches.
- Certain radiographs: It consist of Periapical radiograph, Bitewing and Panoramic radiographs. They provide vital information about the teeth and their supporting structures.
- Facial photographs: Facial photographs are a good diagnostic tool because both the frontal and profie facial analysis is carried out.
Supplemental Diagnostic Aids
- Specialized radiographs: It consist of Cephalometric radiographs, Occlusal radiography, Selected lateral jaw view, Cone shif technique.
- Electromyographic examination of muscle activity: It is the procedure which is used to record the action potentials formed in voluntary muscles when they are excited. It is used to study role of musculature in craniofacial growth. It also shows activity of mandibular elevators and depressors.
- Hand and wrist radiographs to assess bone age: They assess skeletal maturity status of an individual.
- Diagnostic set-up: Diagnostic set up is made from an extra set of trimmed and polished study models. Individual teeth and their associated alveolar processes are sectioned of and replaced on the model base in desired positions. Diagnostic set up thus helps in simulating various tooth movements which are planned for patients.
- Occlusograms: An occlusogram is 1:1 reproduction of occlusal surfaces of plaster models on an acetate tracing paper. Upper tracing should be oriented to lower tracing by help of grooves cut in back side of plaster models. Occlusograms develop ideal natural individualized arch form. They also predict occlusal relationship.
Question 8. Write short note on smile analysis in orthodontics.
Answer. Smile analysis is the prerequisite for proper treatment planning and diagnosing the orthodontic problem.
Types of Smile
- Posed smile: It is voluntary and should not be accompanied by any of the emotion. Pose smile is static and can be sustained. Pose smile is actually the learned greeting which is characterized by less lip elevation.
- Unposed smile: This is natural and shows authentic human emotion. This is spontaneous and is characterized by more lip elevation.
Features of Smile
Following are the three characteristics of smile, i.e.
- Vertical characteristics
- Transverse characteristics
- Oblique characteristics
Vertical Characteristics
- It has two main features, i.e.
- Pertaining to incisor display
- Pertaining to gingival display
- Inadequate incisor display is due to vertical maxillary deficiency which is restricted to lip mobility as well as short clinical crown.
- In persons having normal smile, gingival margins of canine are coincident with upper lip. Lateral incisors should be positioned slight inferiorly.
- Presence of gummy smile is associated with the vertical maxillary excess.
- Amount of incisor proclination can affect how much incisors are displayed on smile. Flare incisors reduce gingival display while upright maxillary incisors increases incisor display.
Transverse Characteristics
It consists of three important features:
- Buccal corridor width
- Arch form
- Transverse cant
Buccal Corridor Width
- Calculation of buccal corridor is done from mesial line angle of maxillary first premolar to inner portion of commissure of lip.
- Representation of corridor is done by ratio of intercommissure width divided by distance from one maxillary fist premolar to opposite side of fist premolar.
- Excessive wide buccal corridor is called as negative space.
Arch Form
- It plays an important role in the form of smile.
- Patients having collapsed arch and narrow maxilla shows narrow smile and their buccal corridor is wide.
- As orthodontic expansion of arch is carried out it improves smile by decreasing buccal corridor.
- Transverse smile dimension also get improved.
Transverse Cant
- Appearance of transverse cant or tilt of the smile line can be due to asymmetrical vertical growth of arches or due to differential eruption of teeth.
- Ideally transverse cant should be absent.
Oblique Characteristics
- Maxillary occlusal plane from premolar to premolar is consonant along with curvature of the lower lip on smiling.
- If lower lip shows deviation on smiling there is downward tilt of posterior maxilla or upward tilt of anterior maxilla.
Question 9. Write short note on functional orthodontic examination.
Or
Describe functional examination of face (physiologic examination).
Answer. Functional orthodontic examination studies dynamic nature of stomatognathic system for the optimal functioning.
Functional orthodontic examination identifis the etiology of malocclusion and helps in planning the type of orthodontic treatment which is initiated.
Detailed functional orthodontic examination consists of:
- Examination of postural rest position and maximum intercuspation
- Examination of path of closure
- Examination of TMJ
- Examination of orofacial dysfunctions
Postural Rest Position
- This is the position of mandible at which the muscle which closes the jaws and those which open them are in a state of minimum contraction to maintain the posture of the mandible.
- At postural rest position, a space exist between they maxillary and mandibular jaws which is known as freeway space. Normally it is 3 mm in canine region.
- Various methods are there to assess the postural rest position. At the time of examination patient should be seated upright, with back unsupported and asked to look straight ahead.
- Following are some of the methods which are used to correct the postural rest position:
- Phonetic method: Ask the patient to repeat some of the consonants such as ‘M’ or ‘C’ or repeat the word such as ‘Mississippi’. Mandible return to the postural rest position 1 to 2 seconds aftr the exercise. Ask the patient not to change the jaw, lip or tongue position after phonation, as dentist part the lips to study interocclusal space.
- Command method: Ask the patient to perform certain functions such as swallowing. Mandible tends to return to the rest position following this act.
- Non-command method: Observe the patient as he speaks or swallows. Patient should not be aware that he is examined. This is done by talking about various topics unrelated to the patient while observing him or her.
Methods Employed to Measure Interocclusal Clearance
Following are the method:
- Direct intraoral procedure: Vernier Calipers can be used directly in patient’s mouth in canine or premolar region to measure the freeway space.
- Direct extraoral procedure: Two marks should be placed, one on the nose and another on the chin and mid-sagittal plane. Distance between these two points is measured after instructing the patient to remain at the rest position. Later on ask the patient to occlude the teeth and distance between two points should be measured again. Distance between two readings is known as freeway space.
- Indirect extraoral procedure: Two of the lateral cephalograms at rest position and another in centric occlusion help in establishing the freeway space.
Evaluation of Path of Closure
Path of closure is the movement of mandible from rest position to the habitual occlusion. Abnormalities of the path of closure is seen in some form of the malocclusion.
- Forward path of closure: This occurs in patients with mild skeletal prenormalcy or edge to edge incisor contact. In these patients mandible is guided to more forward position to allow mandibular incisors to go labial to maxillary incisors.
- Backward path of closure: In Class II division 2 cases there is presence of premature incisor contact due to retroclined maxillary incisors. So mandible is guided posteriorly to establish the occlusion.
- Lateral path of closure: Lateral deviation of mandible to right or lef side is associated with occlusal prematurities and narrow maxillary arch.
Examination of TMJ
- Functional examination routinely consists of auscultation and palpation of temporomandibular joint and musculature associated with mandibular opening.
- Examine the patient for symptoms of temporomandibular joint problems such as clicking, crepitus, pain of masticatory muscles, limitation of jaw movement, Hypermobility and the morphological abnormalities.
- Maximum mouth opening should be determined by measuring distance between maxillary and mandibular incisal edges with mouth wide open.
- Normal inter-incisal distance is 40 to 45 mm
Examination of Orofacial Dysfunctions
It consists of analysis of following functions, i.e. swallowing, lips, tongue, speech and respiration.
Examination of Swallowing Pattern
- In newborn tongue is relatively large and protrude between gum pads and take part in establishing the lip seal. This swallowing is known as infantile swallow and is seen till one and a half to two years of age.
- As buccal teeth start erupting infantile swallow is replaced by the mature swallow.
- Persistence of infantile swallow can lead to malocclusion. So the swallowing pattern of the individual should be examined.
- Persistence of infantile swallow is indicated by presence of following features:
- Protrusion of tip of tongue
- Contraction of perioral muscles during swallowing
- No contact at molar region during swallowing.
Examination of Tongue
- Assess posture, size, shape and function of tongue.
- Size of tongue can be microglossia, i.e. small tongue or macroglossia, i.e. dentition is spaced and crenations are seen on lateral border of tongue.
- Tongue thrust is the most common functional aberration of tongue. Anterior tongue thrust is associated with anterior open bite and lateral open bite is seen with lateral tongue thrust. Patient having complex tongue thrust occlude teeth in molar region.
- Posture of tongue can lead to malocclusion. Normal resting position of tongue is retracted tip lying just behind mandibular incisors and lateral border rest on linguo–occlusal surface of mandibular posterior teeth. In class II tip of the tongue is more retruded in rest position while in class 3 tip of the tongue lies forward.
Examination of Lips
- Assessment of lips is done for confiuration, functioning and presence of dysfunctions.
- Lip dysfunctions which occur commonly are lip thrust and lip insuffiency.
- Dysfunctions of lip are observed when patient is speaking or swallowing.
- During swallowing pronounced lip activity is unphysiologic.
Examination of Respiration
- Respiration should be examined to check whether nasal breathing is present or not.
- If there is difficulty in nasal breathing, there is presence of mouth breathing.
- Mouth breathing leads to disturbed orofacial musculature which leads to adenoid facies.
- Various tests for assessing mouth breathing are visual examination, mirror test, buttrfl test and water holding test.
- Mirror test: Held a double sided mirror between nose and mouth. Fogging over the nasal side of the mirror indicates nasal breathing while fogging towards oral side indicates oral breathing.
- Cotton test: Buttrfl shaped piece of cottn is placed over the upper lip below nostrils. If cottn flttrs down, this indicates nasal breathing. This test determines unilateral nasal blockage.
- Water test: Ask the patient to fil his mouth with water and retain it for the period of time nasal breathers accomplish this with ease while mouth breathers feels difficulty.
- Observation: In nasal breathers the external nares get dilated at the time of inspiration. In mouth breathers, there is no change in external nares or they can constrict during inspiration.
Examination of Speech
- Various malocclusions can cause defects in the speech due to interference with movement of tongue and lips. This is observed by undergoing conversation with the patient.
- Ask the patient to read out from a book or ask to count from 1 to 20 while observing the speech.
- Patients having tongue thrusting habit tend to lisp while patients with clef palate may have a nasal tone.
Question 10. Write short note on OPG.
Or
Write short note on uses of panoramic radiography.
Answer. Full form of OPG is Orthopantomography. It is also called as panoramic radiography or rational radiography. Panoramic radiography is a radiographic procedure that produces a single tomographic image of the facial structures including both maxillary and mandibular arches and their supporting structures.
Indications/Uses
- As a substitute for full mouth intraoral periapical radiographs.
- For evaluation of developmental anomalies and TMJ dysfunction.
- For evaluation of tooth development for children, the mixed dentition and also the age.
- To assist and assess the patient for and during orthodontic treatment.
- To establish the site and size of lesions such as cysts, tumors and developmental anomalies in the body and ramus of the mandible.
- For follow-up of treatment, progress of pathology or postoperative bony healing.
- Prior to any surgical procedures such as extraction of impacted teeth, enucleation of cyst, etc.
- For detection of fractures of the middle third and the mandible aftr facial trauma.
- To study the antrum, especially to study the flor, posterior and anterior walls of the antrum.
- Periodontal disease as an overall view of the alveolar bone levels.
Advantages
- Convenient for the patient and requiring very little patient compliance.
- Useful in patients with trismus and gagging problems.
- Time required is minimal compared to a full mouth intraoral periapical radiographs.
- The patient exposure dose is relatively low compared to a full mouth intraoral periapical radiographs.
- Panoramic radiographs taken for diagnostic purpose are valuable visual aid in patient education.
- The anatomical structures are most identifible and the teeth are oriented in their correct relationship to the adjacent structures and to each other.
- It allows for the assessment of the presence and position of unerupted teeth in orthodontic treatment.
- It demonstrates periodontal disease in a general way. Manifesting a generalized bone loss.
- This view helps in localization of objects/pathology in conjunction with a topographic occlusal view or an intraoral periapical radiograph.
Disadvantages
- Areas of diagnostic interest outside the focal trough may be poorly visualized, e.g. swelling on the palate, flor of the mouth.
- Comparatively this radiograph is of a poor diagnostic quality, in terms of magnifiation, geometric distortion, poor defiition and loss of detail.
- There is an overlapping of the teeth in the bicuspid area of the maxilla and the mandible.
- In cases of pronounced inclination, the anterior teeth are poorly registered.
- The density of the spine, especially in short necked people can cause lack of clarity in the central portion of the fim.
- Number of radiopaque and radiolucent areas may be present due to the superimposition of real/double or ghost images and because of sof tissue shadows and air spaces.
- Due to prescribed rotation, patient with facial asymmetry or patients who do not conform to the rotation curvature cannot be X-rayed with any degree of satisfaction.
- Artifacts are easily misinterpreted and are more commonly seen, e.g. nose ring as a periapical radiopaque lesion, earring as a calcifiation in the maxillary sinus.
- OPG shows an oblique, rather than true lateral view of the condylar heads and hence, the joint space cannot be accurately assessed.
- The cost of the machine is very high.
Question 11. Write short note on facial photographs.
Answer. Facial photographs are of great importance as they act as a diagnostic tool as with the help of facial photographs frontal and profile facial analysis can be done.
It is always preferred to take profie and frontal view photographs by help of two cameras. This helps in reproducing same position of patient for both profie and frontal views.
Facial photographs have extraoral views and intraoral views.
Extraoral Photographs
Following are the extraoral views:
- Profile
- Frontal
- Oblique
Profile view
- Profile at rest: In this view, the lips should be relaxed.
- Profile smile: This view helps in the assessment of angulations of the maxillary incisors.
Frontal view
- Frontal at rest: If lip competence is present, the lips should be in repose of the mandible in rest position.
- Frontal view with the teeth in maximal intercuspation, with the lips closed even if this strains the patient.
- Frontal dynamism (Smile): This type of frontal facial photographs helps in the assessment of amount of incisors shown on smile (percentage of maxillary incisors display on smile) and any excessive gingival display.
- A close-up image of the posed smile: A close-up image of the posed smile is used for careful analysis of the smile relationship.
Oblique (Three quarter, 45°) view
In this type of facial photograph, the patient in natural head position, looking 45° to the camera. Oblique facial photographs are taken in the following three views, which are helpful in the orthodontic diagnosis:
- Oblique at rest: Oblique at rest photograph is useful for the examination of the midface and is particularly informative of midface deformities, including nasal deformity.
- Oblique on smile: Oblique on smile reveals characteristics of the smile not obtainable on the frontal view and certainly not obtainable through any cephalometric analysis.
- Oblique close-up smile: Oblique close-up smile view helps in more precise evaluation of the lip relationship of the teeth and jaw that is possible using the full oblique view.
Intraoral Photographs
The intraoral photographs include the following fie views:
- Right lateral view
- Left lateral view
- Anterior/frontal view
- Maxillary occlusal view
- Mandibular occlusal view
Uses of Facial Photographs
- They provide permanent record of the patient’s pretreatment appearance as well as profie.
- Facial photographs lead to the analysis of facial profie and frontal analysis.
- They are used to assess face type and facial asymmetry.
- Intraoral photographs help in the correlation of both clinical and study model fidings.
- Helps in assessing treatment changes.
- They are used to motivate patients.
- They are used to monitor the progress of treatment.
- Photographs of parents and siblings helps in diagnosis of hereditary pattrn.
Question 12. Write short note on study casts.
Answer. Study casts are essential diagnostic aids.
- Orthodontic study models are accurate plaster reproduction of the teeth and their surrounding soft tissues.
- Study models are three-dimensional view of the maxillary and mandibular dental arches.
Ideal Requisite of Study Model
- Models should accurately reproduce the teeth and their surrounding sof tissue without any distortion.
- Models are to be trimmed in such a manner that they are symmetrical and pleasing to the eye. This enables instant identifiation of asymmetries in the arch form.
- Models are to be trimmed in such a way that when replaced on their backs, they accurately reproduce the occlusion.
- Study model should have a clean-smooth and nodule free surface.
- Study models should not only depict the teeth but should also reproduce as much of the alveolar process as possible.
Use of Study Models
- They enable the study of occlusion from all aspect.
- They enable accurate measurement to be made in a dental arch. They help in measurement of arch length, arch width and tooth size.
- They help in assessment of treatment progress by dentist as well as the patient.
- They help in assessing the nature and severity of malocclusion.
- They are helpful in motivation of the patient and to explain the treatment plan as well as progress to the patient and parents.
- Study models make possible to stimulate treatment procedure on the cast such as mock surgery.
- Study models are useful to transfer records in case the patient is to be treated by another clinician.
Parts of a Study Model
- Anatomic portion
- Artistic portion
- Anatomic portion: The anatomic portion is that part of the study model which is the actual impression of the dental arch and its surrounding structures. Anatomic potion is usually made of stone plaster.
- Artistic portion: This part consists of a plaster base that supports the anatomic portion.
In a well trimmed study casts, ratio between anatomic and artistic portion should be 2:1. Tooth portion, sof tissue portion and artistic portion should be 1:1:1. Completed model is 13 mm in height in both anterior and posterior region.
Fabrication of Study Cast
Impression Making
- Obtain a good alginate impression for proper fabrication of orthodontic casts.
- Orthodontic study models reproduce as much of supporting structures as possible, so it is recommended to use high flnge orthodontic trays that extend deep in buccal and lingual sulci.
- Selected tray should cover last erupted molar and have clearance of 3 mm between the teeth and tray.
- A good impression shows a peripheral roll and records the muscle attchments. Retromolar pad in the mandible and tuberosity in maxilla should be included.
Disinfection of Impression
- Impression should be rinsed in water and disinfected by biocide solution to remove microorganisms, plaque, mucin and other debris which reduces the quality of surface reproduction.
- As disinfection is completed, once again impression is rinsed in water to clear residual disinfectant.
Casting of Impression
- Rinse the impression and excess water is shaken out.
- Good quality of stone model plaster is used to pour the impression.
- It is always best to use mechanical spatulator or vacuum mixer.
Basing and Trimming of the Cast
- Rubber base formers are used to pour artistic portion or the base. They confie the plaster and are fabricated to shape of the base in artistically pleasing contour.
- Tray orientation should be done in the manner that anatomic portion is in the center of rubber mould with occlusal plane parallel with the cast base of base former.
- Guidelines for trimming the cast:
- Upper model should be cut by back edge at right angles to middle line and the front surfaces are cut so that point of intersection of front surface is in line with middle line of palate.
- Sides of the model should be cut symmetrically about the middle line
- Upper model act as a guide in trimming the lower model
- By set square, back corners of upper and lower model are trimmed. Front of lower model is trimmed to the smooth curve.
- Distal corners should be cut symmetrically to middle line conveniently with models in occlusion. Sides of model are cut symmetrically about the middle line.
- Occlusal plane should be parallel to top and bottm of study casts.
- After trimming the study casts should be symmetrical. Upper study cast should have seven sides and lower study casts have six sides when viewed from occlusal plane.
Finishing and Polishing
- Final fiishing of the artistic portion of dental cast is done by fie-grained waterproof sand paper.
- Removes the bubbles appear at gingival margin by small universal sealer and those in mucobuccal fold area are removed by Kingsley type scraper.
- Final polishing is done by placing the cast in soap solution for one hour and later removed and rinsed under the warm water.
- Dry the cast and buf them so that they acquire smooth and shiny surface.
- Use model storage boxes to store fiished study models for future reference.
Advantages
- Allows more objective assessment of malocclusion as compared to photograph and clinical examination.
- By help of study cast occlusion from lingual aspect can be seen easily.
- They are the permanent records of patient.
- Less expensive.
- Easily duplicated.
Disadvantages
- Occupies storage space.
- Can break on fall.
- Information of soft tissues should not be obtained.
- Teeth and facial profile should not be elicited.
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