Treatment Plan for Class I Malocclusion PDF

***TREATMENT PLAN*** *Class I Malocclusion* - *Definition: Class I malocclusion is characterised by a normal molar relationship where the mesiobuccal cusp of the upper first molar occludes with the buccal groove of the lower first molar, but with other dental problems present.* -...

***TREATMENT PLAN*** *Class I Malocclusion* - *Definition: Class I malocclusion is characterised by a normal molar relationship where the mesiobuccal cusp of the upper first molar occludes with the buccal groove of the lower first molar, but with other dental problems present.* - *Common Dental Problems: Common issues include crowding, spacing, bi-maxillary proclination, transverse discrepancies, and vertical discrepancies.* - *Aetiology:* - *Skeletal: Skeletal factors in the A-P, transverse, and vertical planes contribute to Class I malocclusion.* - *Dentoalveolar Compensation: This refers to the natural alterations in tooth position to limit the occlusal effects of skeletal discrepancies. It\'s influenced by soft tissue forces, tooth eruption, occlusal forces, and mesial drift. It occurs in all three planes and is common in Class III cases. Dentoalveolar compensation can sometimes improve a patient\'s profile.* - *Soft Tissue: Soft tissues play a role in crowding, spacing, bi-maxillary proclination, open bite, and crossbite.* - *Dental: Tooth/arch size discrepancies, which can be genetic or environmental, lead to crowding or, less commonly, spacing.* - *Treatment Planning:* - *Extraction in One Arch: It\'s generally not recommended to extract only in one arch in Class I cases because the goal is to maintain intercuspation and achieve Class I canine and incisor relationships. Space requirements should be equal in both arches. The same number of teeth should be removed in both arches to preserve the correct relationships.* - *Midline: A 1-2 mm upper midline shift is often manageable. A shift of 3mm or more might indicate a need for extraction on the contralateral side. A lower midline shift may be acceptable if occlusion is correct.* - *Incisor Inclination: Incisor inclination can be evaluated using cephalometry and profile smile. Adjust incisor inclination when proclined clinically, if there is a chief complaint, or if not due to compensation.* - *Crowding:* - *Incisor A-P movement: Retraction of 2mm requires 4mm of space, while advancement of 2mm provides 4mm of space.* - *Larger overjets (6mm or more) requiring upper retraction need slightly less space due to arch form change, with an additional 1mm of space created on each side during canine expansion. So, for 6mm retraction, only 10mm of space is required instead of 12mm.* - *Space can be created through extractions, transverse expansion, A-P arch lengthening, IPR, distalization, or maintaining leeway space.* - *Expansion in the upper arch provides space, but can cause functional shifts and relapse. There are limits and drawbacks to expansion in the lower arch.* - *Distal movement of the buccal segments can create space, but is mechanically difficult in the mandibular arch. In the maxillary arch, it can be achieved with extraoral traction.* - *Proclination of incisors can create space, but excessive proclination should be avoided.* - *IPR principles: Precautions include cooling and fluoride use.* - *Anchorage: If 25-30% of extraction space is needed, apply minimal anchorage and extract 5's. If 50% is needed, apply moderate anchorage and extract 4's.* - *Incisor Considerations:* - *Proclined incisors may indicate an extraction case, the need for greater space from 4\'s than 5\'s, less than minimal anchorage, and, if maximum, the need for torque control.* - *Retroclined incisors may suggest a non-extraction case, greater space from 5\'s than 4\'s, minimal anchorage, and the need for incisor proclination.* - *Class I Cases: In a Class I case, if all teeth are similar and there is a midline shift, the treatment plan should involve extracting four teeth, ensuring that the teeth are extracted equally on both sides. The decision to extract should be based on what is needed to solve the issue.* - *The treatment plan should not overcomplicate things by overthinking the midline, inclination or other issues. The focus is on correcting the Class I malocclusion and then addressing secondary issues.* - *Clinical Significance: Class I malocclusions are common, and treatment focuses on addressing specific dental issues while maintaining a Class I molar relationship.* - *It is essential to ensure correct diagnosis when planning treatment, for example, if a supplementary tooth is not identified for extraction as part of a plan for extractions, the case is deemed to have failed, and the treatment plan is not valid.* - *Scientist: Proffit is mentioned with regards to the classification of crowding, and his system is different from the systems used in the Royal College and the London Space Analysis, and his system considers a mild crowding of up to 8-9mm.* *Class II Malocclusion* - *Definition: Class II malocclusion is defined by a distal relationship of the mandible to the maxilla, where the mesiobuccal cusp of the upper first molar occludes mesial to the buccal groove of the lower first molar. Class II is further divided into Division 1 and Division 2.* - *Class II Division 1: Characterised by protruded upper incisors.* - *Class II Division 2: Characterised by retroclined upper incisors.* - *Prevalence: Class II malocclusion has a prevalence of 15-20% for Division 1 and 10-18% for Division 2.* - *Aetiology:* - *Skeletal: Skeletal discrepancies contribute to Class II.* - *Soft Tissue: Soft tissue effects are determined by the skeletal pattern and how the anterior oral seal is produced.* - *Dental: Labial displacement of upper incisors or lingual displacement of lower incisors. Crowding is common in class II div 2 cases and is exacerbated by the retroclination of upper and lower incisors.* - *Habits: Duration of habits can affect development.* - *Treatment Planning:* - *Keys of Treatment Planning: Chief complaint, age and gender, buccal segment, incisors (inclination and overbite), degree of crowding, anchorage and end result, profile and skeletal discrepancy, and cephalometry.* - *Growth Modification:* - *Used to correct Class II by influencing jaw growth.* - *Not recommended for severe skeletal discrepancies.* - *Early treatment with functional appliances can be beneficial.* - *Appliances include headgear, twin blocks, and activators combined with headgear.* - *Headgear can provide maxillary restraint and distalization.* - *Camouflage:* - *Performed with fixed appliances, and suitable for mild to moderate cases.* - *Involves extractions and the use of Class II elastics.* - *It is not used in severe skeletal cases.* - *Extraction Pattern: In Class II cases, it is preferable not to extract in the lower arch if possible, but if there is crowding then extractions may be necessary.* - *Class II Elastics:* - *Intermaxillary traction is used to deliver an anterior force to the mandibular teeth and a posterior force to the maxillary teeth.* - *They are used to correct a half-unit Class II molar relationship.* - *Side effects include extrusion of mandibular posterior and maxillary anterior teeth.* - *Unilateral Class II elastics correct unilateral Class II and lower midline shift but can cause canting of the occlusal plane.* - *En Masse Retraction: Used in Class II cases.* - *Combined Orthodontics & Surgery: Indicated for severe skeletal discrepancies and when there is patient concern. Surgical procedures include mandibular advancement and maxillary setback.* - *Removable Appliances: Can be used in certain cases.* - *Class II Division 2:* - *Modified Twin blocks and Twin Blocks with fixed appliances can be used for growth modification.* - *Removable appliances with ELSA (an extraoral appliance) or anterior bite planes are options.* - *Extraction patterns should try to avoid extractions in the lower arch.* - *Incisor Inclination: In Class II cases, incisor inclination is important and the upper incisors are often labially displaced, whilst the lower incisors may be lingually displaced. Upper incisor inclination is 123 and lower incisor inclination is 114.* - *Clinical Significance: Management of Class II involves considering growth, dental compensations, and skeletal discrepancies to provide the best treatment outcome. Treatment decisions vary depending on the severity of the case and the patient's specific needs. If there is mild crowding, then often only the upper arch needs to be treated, but if the crowding is more severe, then both arches will require treatment. If there is a full unit class II with mild crowding in the lower arch in an adult, extraction in the lower arch should be avoided.* - *Stability: Relapse is a consideration in Class II cases.* - *Scientist: Bishara is referenced with regard to intermaxillary traction.* *Class III Malocclusion* - *Definition: Class III malocclusion is characterised by a mesial relationship of the mandible to the maxilla, with the mesiobuccal cusp of the upper first molar occluding distal to the buccal groove of the lower first molar.* - *Prevalence: Class III malocclusion occurs in 3% of Caucasians and 5-10% of Japanese individuals.* - *Aetiology:* - *Skeletal and Growth: Skeletal factors and growth patterns contribute to Class III.* - *Dental: Premature contacts displacing the mandible anteriorly and lingual eruption of permanent central incisors can be causes.* - *Soft Tissue: Favorable when lip competency can be achieved.* - *Treatment Planning:* - *Keys of Treatment Planning: Chief complaint, age and gender, buccal segment, incisors, degree of crowding, end result and anchorage, skeletal discrepancy, profile, and cephalometry.* - *Incisors: Consider the ability to achieve edge-to-edge, the presence of a functional shift, incisor inclination, periodontal status of the lower incisors and overbite. Assess the degree of mobility and pocket depth associated with the lower incisors, and determine the prognosis, as they can be displaced labially and suffer gingival recession and potential PDL damage.* - *Signs of Maxillary Retrusion: Para-nasal flattening, flat nasal bridge, obtuse nasolabial angle, prominent nasolabial fold, reduced incisor show, and lower scleral show.* - *Cephalometric Analysis:* - *ANB: Usually normal in pseudo Class III, but negative in true Class III with a smaller SNA or a larger SNB. Individual variations in cranial base angle and flexure may alter this angle.* - *Wits appraisal: Useful to discriminate between patients requiring surgical or non-surgical treatment.* - *Gonial angle: Typically more obtuse in Class III cases and average in pseudo Class III cases.* - *Incisal inclinations: Upper incisors are often tipped labially and lower incisors are tipped lingually as a compensation in skeletal Class III. Lower incisors are normally inclined or proclined in pseudo Class III.* - *Treatment Options:* - *Upper Incisor Proclination: Indicated when incisors are retroclined and there is forward mandibular displacement. Precautions are needed when proclining upper incisors in mixed dentition, due to the risk of resorption of the roots of the upper second incisor against the upper canine follicle, so treatment may need to be delayed.* - *Early Treatment: Early treatment is indicated in skeletal Class III with retrusive maxilla and a normal or mildly prognathic mandible with a deep overbite and average or reduced lower anterior face height. Protraction elastics are attached near the upper canines with a downward and forward pull of 30 degrees to the occlusal plane.* - *Functional Appliances: These can be used to modify growth.* - *Bone Anchorage: Class III elastics to skeletal anchors can be more effective than reverse-pull headgear for moving the maxilla forward.* - *Camouflage: Done with fixed appliances, and appropriate for mild cases. It is not done in severe cases.* - *Try not to extract uppers in class III cases. If upper arch is well-aligned no extractions are needed. If upper arch is crowded then extractions can be considered.* - *Class III elastics deliver an anterior force on the upper arch and a posterior force on the lower arch, proclining the upper incisors and retroclining the lower incisors. Side effects of class III elastics include extrusion of posterior maxillary and anterior mandibular teeth. Unilateral elastics can correct unilateral class III and lower midline shift, but can cause canting of the occlusal plane.* - *Use heavy archwires in the upper arch to avoid molar rotation and light wires in the lower arch to help in tipping and correction of reverse overjet. Monitor molar extrusion to avoid an anterior open bite and prevent it using headgear or miniscrews. Space can be gained from the rotation of the occlusal plane, but the limit is half a unit class III.* - *In retroclined lower incisors or distally tipped lower canines, maintain the tip and torque to correct the reverse overjet. The lower canine bracket can be placed passively, or swapped, the lower incisors can be bypassed during initial alignment until after extraction and lower canine retraction. Use MBT brackets and avoid using rectangular wires in the lower arch. Retraction should be done on a round wire and lacebacks can be used to prevent mesial tipping of the canines.* - *Combined Orthodontics & Surgery: Indicated for severe skeletal discrepancies with an ANB of less than -4, L1/MND of less than 83, and MX/MND ratio less than 0.84. Surgical procedures include maxillary advancement and mandibular setback.* - *Decompensation: Extract upper 4's to achieve at least a full unit Class III. No extraction if the buccal segments are full unit class III.* - *Relapse: There is a higher risk of relapse when camouflaging Class III in growing cases, as mandibular growth is counterproductive to the treatment outcome, unlike Class II cases where mandibular growth can help improve the occlusion.* - *Types of Class III cases* - *Skeletal Class III with Class III buccal segment.* - *Skeletal Class III with Class I buccal segment.* - *Functional shift cases.* - *Class III with lower mesial drift.* - *Clinical Significance: Class III malocclusions present challenges in treatment due to the impact of growth and the difficulty in achieving stable results. It\'s important to assess the skeletal and dental components to determine the most appropriate treatment approach. In Class III cases with a reverse overjet, lower incisors may be retroclined.* - *Treatment Decisions:* - *In cases of skeletal class III with mandibular excess, early treatment is not indicated and treatment should be delayed until after cessation of adolescent growth.* - *When assessing camouflage, important indicators include chief complaint, occlusal parameters, incisor inclination, degree of skeletal discrepancy, soft tissue profile and amount of anterior crowding in the upper arch.* - *If the patient can achieve edge-to-edge without complaining of chin prominence, it may be an indication for camouflage. However, if the cephalometric indicators are consistent with other findings then surgical intervention may be required.* - *Scientist: Kerr 92 is referenced with regard to the assessment of severe skeletal discrepancies. Proffit is also mentioned with regard to the movement of the maxillary incisor roots when planning proclination in mixed dentition cases. Wennström (1990) stated that the thickness of the soft tissue is more important than its width.* *Let me know if you would like me to elaborate on any of these points.* ***DIAGNOSIS*** ***Extra-Oral Assessment*** ***Key Concepts:*** - ***Patient-Centered Approach:** Prioritising the patient\'s chief complaint is crucial. The patient\'s perception of their aesthetic concerns guides treatment.* - ***Systematic Evaluation:** Using specific anatomical points and planes to assess facial dimensions.* - ***Three Dimensions:** Assessing anteroposterior (A-P), vertical, and transverse relationships.* - ***Natural Head Position (NHP):** Assessing the patient in a relaxed, upright position with eyes looking forward to avoid false readings.* - ***Clinical Judgement:** Clinical assessment is essential to guide treatment decisions, sometimes taking precedence over cephalometric findings.* ***Details:*** - ***Antero-posterior Dimension:*** - ***A\' and B\' Points:** Palpating the soft tissue A and B points to assess jaw relationship. A normal relationship has a 2-3mm distance between the mandible and the maxilla, with a straight profile. Class II has a retrusive mandible and a convex profile, and Class III has a retrusive maxilla and a concave profile.* - ***Zero-Meridian Line (Gonzalez, 1962):** A vertical line from soft tissue Nasion to assess the position of the maxilla and mandible. In Class I, the soft tissue A-point is typically 2-3mm ahead of this line, and the soft tissue B-point is 0-2mm behind.* - ***Profile Angle (Arnett):** Measuring the angle formed by lines connecting the Glabella-Subnasale and Subnasale-Pogonion. Class I is 5-15°, Class II is more than 15°, and Class III is less than 5°.* - ***Ethnic variations** must be considered when assessing A-P relationships, as there is variation in lower facial protrusion, with African patients having more protrusive profiles compared to white Europeans.* - ***Vertical Dimension:*** - ***Lower Anterior Face Height (LAFH):** Assess the proportions of the face, with the face ideally divided into three equal vertical parts, and the lower face being further divided into a 1/3 to 2/3 ratio. Variations in these proportions are categorised as long or short face types.* - ***Frankfort-Mandibular Plane Angle (FMPA):** Increased FMPA indicates increased vertical dimension; reduced FMPA indicates decreased vertical dimension.* - ***Transverse Dimension:*** - ***Facial Midline:** Evaluate using the glabella-philtrum line and interpupillary line. The chin point should be coincident with the glabella-philtrum line.* - ***Rule of Fifths:** Assess facial proportions by dividing the face into five equal parts.* - ***Bird\'s-Eye View:** Assessing facial symmetry from above.* - ***Submento-Vertical View (Worm\'s-Eye View):** Evaluating facial symmetry from below.* - ***Occlusal Cant:** Assess for any asymmetry in the occlusal plane relative to the interpupillary line and the horizontal plane.* ***Clinical Significance:*** - ***Identifying Etiology:** Helps determine the cause of malocclusion. For example, the zero-meridian line can determine whether a skeletal discrepancy is due to the maxilla or mandible.* - ***Mental Picture:** Assists the clinician in developing a mental picture of the malocclusion, and aids in the formulation of a treatment plan.* - ***Treatment Planning:** Informs possible treatment plans.* - ***Limitations of Cephalometrics:** Clinical assessment is important because cephalometric norms may not align with aesthetic goals, soft tissue changes are linked to tooth position and not the skeleton, and soft tissues are next to teeth and influence lip position.* - ***Head Orientation:** It is essential to assess the patient in NHP, as tilting of the head can cause false readings.* - ***Condylar position:** It is essential to assess for mandibular displacement due to premature contact by examining the patient in the retruded contact position.* ***Soft Tissue Assessment*** ***Key Concepts:*** - ***Soft Tissue Focus:** The position of soft tissues, particularly the lips, is important in treatment planning and assessing skeletal discrepancies.* - ***Influence on Aesthetics:** Soft tissues greatly impact facial appearance. The patient\'s focus is often on their profile rather than their teeth.* - ***Lip Competency:** Assessing the ability to achieve a lip seal with minimal effort.* ***Details:*** - ***Lip Assessment:*** - ***Lip Fullness:** Assess lip prominence using the Ricketts\' E-line or True Vertical Line.* - ***Nasolabial Angle (NLA):** Normal NLA is 102° ± 8°. An acute NLA (\