By doing this it encourages a backward growth rotation, which will reduce the deepbite.
Correct AOB:Headgear can be used to correct an AOB.The type of headgear that would be used is the high pull headgear.This type of pull is above the occlusal plane, which is used to distalise and intrude the maxillary molars and achieve maxillary restraint. By doing this it encourages a forward growth rotation, which will reduce the AOB.
6.4.6 Surgery
Surgery can be given as a treatment option to some patients. The majority of patients who have surgery are severe cases. Patients presenting with a severe retrognathic mandible would be considered. The type of surgery would be a bilateral sagittal split osteotomy (BSSO), which achieves mandibular advancement.
7 Class II Div II Malocclusion
7.1 Definition
The lower incisor edges occlude posterior to the cingulum plateau of the upper central incisors.
The upper central incisors are retroclined and the overjet is minimal or increased. The common feature of this type of malocclusion is proclined laterals.
7.2 Prevalence
Ten per cent of Caucasians present with this type of occlusion.
7.3 Aetiology of Class II Div II
7.3.1 Skeletal Factors
Patients will present with a skeletal class II with a retrognathic mandible and with many features, such as:
Reduced lower anterior facial height (LAFH) and Frankfort‐mandibular plane angle (FMPA)
Forward growth rotation
High lower lip line
Deepbite
Pronounced labiomental fold.
A scissorbite may be seen in the premolar region due to a narrow lower arch.
7.3.2 Soft Tissue Factors
High lower lip line:Retroclination of the upper anterior segment can be seen if there is more than one‐third coverage of the upper central incisors.Lateral incisors have shorter crowns, which can escape the control of the lower lip and procline. The most common feature to be found with a class II div II malocclusion is proclined lateral incisors.
Labiomental fold:The labiomental fold is found between the lower lip and the chin.With a reduced LAFH, the labiomental fold will reflect the soft tissue lip abundance.
Bimaxillary retroclination:This term is used to describe the position of the upper and lower incisors.Bimaxillary retroclination is where upper and lower incisors are retroclined due to a strap‐like lower lip.
7.3.3 Local Factors
Increased interincisal angle:The interincisal angle is used when doing a cephalometric analysis.This angle is located where the long axis of the upper and lower incisors meets.The average value of the interincisal angle in Caucasians is 135°+/−10°.The interincisal angle can differ depending on the position of the incisors.If the interincisal angle is reduced to its mean, then this suggests the patient is a class II div I.If the angle has increased and is larger than its mean, then this suggests the patient is a class II div II; the reason it is larger is the retroclined upper and lower incisors.
Gummy smile:Due to retroclined upper central incisors, patients can be seen with a gummy smile.This is a common feature with a class II div II case.
Retroclined lower incisors:Patients can have retroclined lower incisors.This can be due to:Deepbite, which can trap them.Strap‐like lips, which will retrocline them.
Deep overbite:A deep overbite can also have an effect on the position of the incisors:Deep overbites can trap the lower incisors.The position of the teeth can cause trauma to the palate and to the labial gingivae of the lower incisors from the upper incisors.Can cause reduction of the intercanine width, which can cause a scissorbite in the premolar region.
Crowding:Crowding can be found within a class II div II case.Retroclined incisors are often associated with this.
Proclined or mesiolabial rotated lateral incisors:This is a very common feature that is found within a class II div II case.Causes of this can be:CrowdingFailure of lower lip control.
7.4 Treatment of Class II Div II
There are six ways to treat a class II div II malocclusion.
7.4.1 No Treatment
Leave the malocclusion and accept the teeth and their discrepancies as they are.
All patients must be informed of all the risks if they wish to take the no treatment option.
7.4.2 Removable Appliance
Anterior expansion screw or Z springs (double cantilever):These are two active components which are found on a removable appliance.Either component can be used to procline the incisors to turn them into a class II div I.
Correct deepbite:A flat anterior bite plane can be incorporated on the removable appliance to help reduce the deepbite.This allows passive lower molar eruption and incisor intrusion.
An alternative to a removable appliance is a sectional fixed U2–2 to turn the malocclusion into a class II div I.
7.4.3 Functional Appliance
Any of these six appliances can be used:Clark’s twin blockBionatorHerbstMedium opening activator (MOA)Clip‐on fixed functional (COFF)Frankel.
These posture the mandible forward to reduce the upper anterior segment and procline the lower anterior segment to reduce the overjet.
7.4.4 Fixed Appliances
With class II div II cases, once the upper anterior teeth are proclined to their normal angulation, the patient will be turned into a class II div I case, where the overjet needs to be reduced.
Extractions:Maxillary first premolars only:This is considered in a mild–moderate crowded case with a well‐aligned lower arch.In this case the maxillary first premolars are considered because more space is gained from these teeth. Due to the need for more space anteriorly to reduce an overjet, this will help to retract the upper incisors.Maxillary first premolars and mandibular second premolars:This is considered in a mild–moderate case with crowding in both arches.Maxillary first premolars would be considered to help retract the upper incisors to
