Shorts

The possibility that a distal step would become class II is very real, and this not self correcting problem. When the central incisors erupt, these teeth use up essentially all of the excess space in the normal primary dentition. With the eruption of the lateral incisors, space becomes tight in both arches.

Normal child will go through a transitory stage of mandibular incisor crowding at age 8 to 9 even if there will eventually be enough room to accommodate all the permanent teeth in good alignment. In other words, a period when the mandibular incisors are slightly crowded is a normal developmental stage.

Continued development of the arches improves the spacing situation, and by the time the canine teeth erupt, space is once again adequate.

Midline diastema Etiology 

Normal developing dentition - (Ugly Ducking Stage)

Parafunctional habits
- Flaccid lips along with poor muscle tone
- Simple Tongue thrust can cause anterior open bite as well as diastema
- Thumb sucking or digit sucking for a prolonged time period 

Retrognathic mandible/ Prognathic mandible 

Frenum attachments
Mesio-distal angulation of teeth
Tooth anomalies (eg. supernumerary teeth, peg laterals, absence of laterals)

Pathological (Juvenile periodontitis)

SOLUTION

The key to success is to use an appliance that is both comfortable, easily retained and predictable such as a simple Hawley retainer with recurve springs or a fixed labial-lingual appliance (including a vertical removable arch for ease of adjustment with a recurve spring to jump the cross-bite). 

Both of these appliances work by tipping the maxillary teeth forward so they are in a normal dental relationship to the mandibular teeth. Once this is accomplished, it will allow future coordinated growth between the maxilla and the mandible

 

Etiology of Tongue thrust
Fletcher has proposed the following factors as being the cause for tongue thrusting. 

Genetic factors : They are specific anatomic or neuromuscular variations in the oro-facial region that can precipitate tongue thrust. e.g. Hypertonic orbicularies oris activity. 

Learned behaviour (habit) : Tongue thrust can be acquired as a habit.

 The following are some of the predisposing factors that can lead to tongue thrusting:
          a. Improper bottle feeding
          b. Prolonged thumb sucking
          c. Prolonged tonsillar and upper respiratory tract infections
          d. Prolonged duration of tenderness of gum or teeth can result in a change in swallowing pattern to avoid pressure on the tender zone.
          
Maturational : Tongue thrust can present as part of a normal childhood behaviour that is gradually modified as the age advances. The infantile swallow changes to a mature swallow once the posterior deciduous teeth start erupting.

Sometimes the maturation is delayed and thus infantile swallow persists for a longer duration of time. 

Mechanical restrictions : The presence of certain conditions such as macroglossia, constricted dental arches and enlarged adenoids predispose to tongue thrust habit. 

Neurological disturbance: Neurological disturbances affecting the oro-facial region such as hyposensitive palate and moderate motor disability can cause tongue thrust habit. 

Psychogenic factors : Tongue thrust can sometimes occur as a result of forced discontinuation of other habits like thumb sucking. It is often seen that children who are forced to leave thumb sucking habit often take up tongue thrusting.

SOLUTION 

The two major symptoms of severe crowding in the early mixed dentition are severe irregularity of the erupting permanent incisors and early loss of primary canines caused by eruption of the permanent lateral incisors. The children with the largest arch length discrepancies often have reasonably well aligned incisors in the early mixed dentition, because both primary canines were lost when the lateral incisors erupted 

After a definitive analysis of the profile and incisor position, these patients face the same decision as those with moderate crowding; whether to expand the arches or extract permanent teeth. In the presence of severe crowding, limited treatment of the problem will not be sufficient and permanent tooth extraction is most likely the best alternative.

In a homogeneous population, the genetic variation is less compared to a heterogeneous population. Malocclusion is influenced by both genetic and environmental factors. A homogenous population, which is more genetically similar, would be expected to have a more uniform expression of dental traits, including a lower incidence of malocclusion, assuming that the specific genetic factors for malocclusion are not prevalent in that particular population. In a heterogeneous population, the greater genetic diversity can lead to a higher incidence of malocclusion due to a wider range of genetic combinations contributing to dental misalignments.

Sutural Hypothesis (or Sutural Dominance Theory) proposed by Harry Sicher and Weinmann, all bone-forming tissues—including sutures, cartilages, and the periosteum—act as primary growth centers.

Jasper jumper is a flexible fixed functional appliance used for Class II correction, consisting of a flexible wire that allows mandibular advancement.