Orthodontics 2 PDF

Doctor: ‫زيد البيطار‬ Writer: 2019 Corrector: ‫مايكل الربضي‬  "If you cannot lift the injustice, at least tell everyone about it” Slide Crossb...

Doctor: ‫زيد البيطار‬ Writer: 2019 Corrector: ‫مايكل الربضي‬  "If you cannot lift the injustice, at least tell everyone about it” Slide Crossbites Doctor's note References: Textbook :An Introduction to Orthodontics Cochrane review articles Aims: 1- Definition of Crossbites 2- classification 3- Aetiology 4- Management Crossbites : An abnormal relationship between opposing teeth in a buccopalatal or labiopalatal direction. - Affecting between 8% and 16% of the population Transverse Occlusal Deviations They can be classified according to : 1- Crossbite or Scissors bite 2- Localized(one or two teeth)or segmental(more than one tooth in quadrant) 3- Unilateral or bilateral 4- With or without mandibular displacement Posterior Crossbite (buccal crossbite): Crossbites generally described in terms of the position of the lower teeth relative to the upper teeth. Recently, some clinicians (especially from the states) describe crossbite by using the individual upper teeth because they think that these teeth are often to be moved to correct the crossbite. Page | 2  "If you cannot lift the injustice, at least tell everyone about it” The most common description which we are referring in this lecture is (the lower teeth relative to the upper teeth) ,so buccal crossbite means: Buccal cusp of lower teeth (molars and premolars )occlude buccal to the buccal cusps of the upper teeth. Aetiology : 1- Local causes: crowding is the most common cause of Posterior Crossbite. usually seen in Upper premolars after early loss of second primary molar which will result in a forward movement of the first permanent molar resulting in these teeth being displaced palatally. in cases of dental crowding, the upper lateral incisors can sometimes become displaced palatally or locked in an upper palatal position, leading to a crossbite of the lateral incisors. This occurs due to the palatal position of the tooth buds during development. 2- Skeletal: A-P, transverse. 3- Soft tissues: habits such as: thumb sucking can result a narrowing of the upper arch leading to a posterior crossbite which usually associated with mandibular displacement. 4- Other: e.g. CLAP (cleft lip and palate) with restrictions of maxillary growth and TMJ with abnormal condylar growth (less common causes of Posterior Crossbite). A palatal displacement of the A midline supernumerary that upper second premolar due to leads to a crowding with upper early loss of the primary second left lateral in a palatal position molar resulting in crossbite. Page | 3  "If you cannot lift the injustice, at least tell everyone about it” Here there are a skeletal causes of crossbite. In the first photo you can see a skeletal Class III malocclusion associated with buccal crossbite due to the mandible growth in a forward position, so the wider part of the mandible comes relative to the narrower part of the maxilla that leads to crossbite. And the opposite can be seen in severe class II where a Scissorbite (can be a more common in this case). In the second photo you can see a transverse narrowing of the maxilla that usually leads to a bilateral posterior crossbite in severe cases. Mandibular Asymmetry: Is abnormal condylar growth usually associated with unilateral Crossbite and there is no evidence of mandibular displacement. so if you have a case that has a unilateral Posterior Crossbite and no mandibular displacement with extraoral features that show Asymmetry with shift of the midline you can suspect the presence of mandibular Asymmetry with abnormal condylar growth. This could happen due to trauma that leads to restriction of the mandibular growth on one side. Benefits of (crossbite)Treatment : 1. Elimination of mandibular displacement that can be associated with TMJ problems (some studies found a link between mandibular displacement and TMJ problems ).so anterior or posterior crossbite with mandibular displacement is an indication of early treatment 2. Space creation: if we have a crossbite , the expansion of the arch can provide space. In severe cases where we have maxillary restriction (e.g. restricted transverse growth), the expansion and correction of the crossbite will create a space for the arch 3. Improvement of smile aesthetics: by expand the upper arch ,especially in the buccal corridors Displacement: A sagittal or lateral movement of the mandible from the rest position to the position of maximum intercuspation as a result of a premature contact" Page | 4  "If you cannot lift the injustice, at least tell everyone about it” So in these photos you can see an early mixed dentition ,the patient here tries to close his teeth from position of rest to the position of maximum intercuspation but the upper right primary canine has a premature contact or interference during this closure preventing him from closing comfortably into a normal occlusion.so the patient is shifting his mandible to the right side in order to achieve a maximum intercuspation. Note : this can be either in transverse(like in this photo)or A-P direction (when we have anterior crossbite) Please, refer to the lecture (9:30) to view the animation. I added (some screenshots from the animations ⬇️) and doctor’s notes As you can see in these photos the patient tries to close comfortably but a premature contact prevents him, that leads to mandibular displacement to one side , this is evident by midline shift and the presence of crossbite Posterior Crossbite: -If associated with(mandibular)displacement may predispose to TMD. -Important to consider aetiology before starting treatment. -one of the indications of early interceptive treatment(in primary or mixed dentition). Page | 5  "If you cannot lift the injustice, at least tell everyone about it” Treatment planning: 1.Aetiology (dental, Skeletal, soft tissue) 2. Age and stage of dentition (because some treatment modalities can be suitable for certain ages while contraindicated for others) 3. Presence of mandibular displacement 4. Other features of malocclusion: e.g. Crowding, overbite ( we need to consider the overbite before starting the treatment with expansion appliances; because the dental expansion leads to buccal tipping of the upper posterior teeth and this usually results in reduction of the overbite). 5. Unilateral crossbite (treated by removable or fixed appliance, especially if associated with mandibular displacement) or bilateral crossbite (need more careful considerations and could indicate A-P or transverse skeletal problem). In the absence of crowding, if no attention has been paid to the malocclusion, sometimes if we expand the patient with bilateral crossbite, it’s relapse could result a unilateral crossbite with displacement, so we can accept bilateral crossbite without any treatment or alterations because first of all; it’s not causing any displacement, so we don’t worry about relapse and chewing function for these patients because they will be normal. 6. Tooth inclination(if we do overexpand to the teeth, especially when we have Skeletal crossbite this will give us abnormal inclination and loading of these teeth which could relapse easily and this leads to reduction of overbite and problems with recession of these teeth). 7. Dental health (if the patient has reduced gingival support, expansion could result in a recession, and then in case of attrition has occurred on these teeth; this could affect the stability of the treatment because the treatment of Posterior crossbite depends on proper posterior interdigitation which could be lost due to attrition). Dental Crossbite: An abnormal relationship between antagonist teeth that is due to deviations in the position or inclination of one or a few teeth Usually in dental crossbite upper teeth are inclined palatally with normal width of the palate so in this case just a simple tipping movement can correct this crossbite. Page | 6  "If you cannot lift the injustice, at least tell everyone about it” Skeletal Crossbite: Anterior or posterior (unilateral or bilateral) crossbite that is due to a sagittal or transverse incoordination in the size or shape of the maxilla and/or mandible. Here we have a narrow upper arch ,the upper teeth are already compensated by flaring buccaly (the teeth are tipped buccaly) , it’s not possible to further tip these upper teeth buccaly to correct the malocclusion so we don’t use upper appliances that give us dental expansion, we use appliances that are capable to do Skeletal expansion to correct the narrowness of the upper arch. TREATMENT OF CROSSBITES: Simple method that can be used for primary or early mixed dentition involves selective grinding of primary canines. So if we have a compatible upper arch and only have posterior crossbite with displacement due to premature contact of the primary canines, simple trimming or grinding of these primary canines (upper or lower) could eliminate this displacement. -Removable appliances can be used to treat a simple crossbite or Scissorbite. -You can see here a T-spring to correct the premolar in Crossbite, and we have a buccal arm on the left side to correct a premolar in Scissorbite, so we have a enough space and retention in this appliance in addition to enough clearance by biteplane to remove any interference during correction of crossbites or Scissorbite Page | 7  "If you cannot lift the injustice, at least tell everyone about it” Expansion with removable appliances: -Mainly tipping -Suitable for small amount of expansion (no more than 4- 5mm) -Need adequate retention -Overcorrection -Retention Please ,refer to the lecture (17:30) to view the animation.I added some screenshots from the animations ⬇️ Page | 8  "If you cannot lift the injustice, at least tell everyone about it” Quadhelix Appliance: Other type of expansion appliances is the Quadhelix which is a metal device constricted in the laboratory around one millimeter wire, it has four helices and usually give us more bodily type of expansion and many advantages.so it is a fixed appliance that give us a correction of the posterior crossbite. From Textbook: The quadhelix is a very efficient, fixed, slow expansion appliance. The quadhelix appliance can be adjusted to give more expansion anteriorly or posteriorly as required, and can also be used to de-rotate rotated molar teeth. When active expansion is complete, it can be made passive to aid retention of the expansion. Cross Elastics : in cases where there is a unilateral crossbite involving a single tooth with palatal tipping of the upper six and buccal tipping of the lower six, the use of elastics can result in buccal tipping of the upper molar and lingual tipping of the lower molar, so elastics are beneficial in the correction of the crossbite. Cross Elastics is worn by the patient and it can be changed every day with new elastics until his next appointment Please ,refer to the lecture (19:33) to view the animation Page | 9  "If you cannot lift the injustice, at least tell everyone about it” Rapid Maxillary Expansion (RME): - Skeletal expansion (when a patient has a constricted maxilla) - indicated for early teens (because no fusion in the Midpalatal suture, this helps in the expansion) - Before fusion of maxillary sutures -Retention period The patient is advised to expand the appliance(turning the screw) twice a day for two weeks to correct the crossbite ,then the appliance will be used as a retainer for few months to fill the bone in expanded area it’s called RBE (rapid maxillary expansion) because most of expansion happens in first two weeks, the patient will note a transitory meet upper median diastema due to this rapid expansion which closes later on during the retention period. The idea of RME is: The rapid expansion will be more Skeletal initially (turning the screw twice a day) rather than dental movement and this will be transferred to the suture area, resulting in expansion. However, during later stages of retention, we will get around 50% of skeletal and 50% of dental expansion (during the retention period) Please ,refer to the lecture (20:40) to view the animation Surgically assisted RME: After the fusion of the midline suture, if we aim to achieve maxillary expansion, we can still utilize RME. However, this requires a surgical procedure in the suture area facilitated by maxillofacial surgeons. The surgical cut is necessary to enable this type of expansion as RME alone, with expansion twice a day, may not suffice Page | 10  "If you cannot lift the injustice, at least tell everyone about it” Please ,refer to the lecture (22:16) to view the animation Segmental maxillary surgery: In more severe cases we rely on maxillofacial surgeons to do the expansion (segmental maxillary surgery) especially if we need a special types of cuts or movements in our patient. Please ,refer to the lecture (22:16) to view the animation Page | 11  "If you cannot lift the injustice, at least tell everyone about it” Scissors bite (lingual crossbite): Buccal cusps of the lower teeth occlude lingual to the lingual cusps of upper teeth These patients can be treated by removable or fixed appliances (more common )with elastic and differential expansion of wire, in severe cases surgery might be indicated. Anterior crossbite: - Upper lateral erupted palatally due to crowding - Risk of attrition and recession in the lower incisors - Pseudo class III : an anterior displacement of the mandible due to presence of crossbite that leads to TMJ problems Anterior crossbite occurs when the upper teeth occlude palatal to lower teeth Note: here we’re talking about lateral incisors crossbite only, because if all centrals and laterals are in crossbite, this is usually a class 3 which is a different topic Treatment considerations: This kind of malocclusion can be treated with removable or fixed appliances and this depends on : - Type of tooth movement : if only tipping movement (use removable appliances), if bodily movement (use fixed appliances ) - Space condition : In cases where inclined upper lateral incisors require adequate space for the correction of crossbite, options such as stripping or extraction of primary canines in the mixed dentition, along with other procedures, may be considered - Lower arch? When we have a proclined lower incisors which need to be controlled and corrected by fixed appliances. - Overbite: The stability of treatment depends on achieving an appropriate overbite. If the overbite is reduced on the teeth that were in crossbites, we need to consider long-term retention - Displacement? The presence of displacement is an important consideration because it provides us with a functional indication for early treatment. - upper canine position is important. If the canines are closely associated with the lateral incisors, it might be advisable to delay the treatment until the canine position improves. Page | 12  "If you cannot lift the injustice, at least tell everyone about it” This case had a crossbite of the for treatment we need a posterior - at the end of the treatment lateral incisor with crowding. biteplane with adequate retention we don’t have enough overbite for the appliance to maintain the correction , the patient was warned about relapse and indicated to wear the appliance on a long term basis stability of correction of crossbites 1- Adequate post-treatment overbite (anterior crossbites). 2- Not excessively tipping the teeth to achieve correction. 3- Good posterior intercuspation. (For posterior crossbite) 4- Favorable anteroposterior and transverse skeletal growth - We will depend on cessation of thumb sucking habit in cases of posterior crossbite that happen due to habits. Goodluck Page | 13