The relation of the upper and lower incisors when in tooth contact (centric occlusion). The British Standards Institute classify the incisor relationship as Class I. We have known for a long time balance related to a skeletal Class II that different incisor on the following criteria: in a subject with an acceptable facial 1) A normal incisor relationship for this purpose and is represented by according to sex.  When that occurs, the first molars will be in contact and the maxillary and mandibular Treatment objectives Achieve Class I molar and canine relationship.
Such a malocclusion has been found to be prevalent in 4. Recent studies have suggested a higher range of asymmetric molar malocclusions in more than 30 per cent of children Keski-Nisula et al. The most common reason for an asymmetric molar relationship was reported to be due to early loss of the primary second molar followed by mesial migration of the permanent first molar Proffit et al.
Other factors which may lead to asymmetry are normal variations in the sequence of tooth eruption, asymmetries in eruption between the right and left sides, genetic influences, and perioral habits Proffit et al. Few attempts have been made to determine the molar relationship in five categories, including half-cusp half-step relationships Behbehani et al. Also, very few attempts have been made to assess the prevalence of an asymmetric molar relationship without the effect of mesial molar migration Behbehani et al.
Prevalence of precise asymmetric molar occlusion can only be achieved by reporting the full range of molar relationships, including half-step deviations, and by excluding subjects with evident mesial molar migration.
Information about the prevalence of canine asymmetries is also very limited Keski-Nisula et al. Because it can be acceptable to finish in Class III or Class II molars when camouflaging a case with sagittal discrepancy, and since it is always important to finish with a Class I canine relationship, information about the canine relation may be more relevant to dictate the severity of malocclusion Behbehani et al.
It is widely accepted that maxillary and mandibular canines are an integral part of facial and dental aesthetics, important for canine guidance, and essential for occlusal stability.
Therefore, reports on canine asymmetries are equally or more important than those on molar asymmetries to describe the severity of malocclusion Keski-Nisula et al. It may be speculated that canine asymmetry would follow molar asymmetry in a similar direction and at a similar severity level Keski-Nisula et al.
The purpose of this study was to examine a large population-based sample of adolescent Kuwaitis in the early permanent dentition to provide an accurate description of the prevalence and severity of occlusal asymmetries in the molar and canine regions. Subjects and methods Following approval by the ethical committee at Kuwait University, Faculty of Dentistry, the sample comprised to year-old Kuwaiti boys and girls according to a stratified cluster sampling method Cochran,defining the students in the public schools of each of the six administrative areas as six different strata and the students in the different private schools as the seventh stratum.
Similar to random sampling procedures in a previous report Behbehani et al.
In this sample, subjects were examined intraorally, while 55 subjects were assessed by evaluating their initial study models. The molar and canine relationships were entered as missing data when these could not be scored due to missing, extracted, or impacted tooth. The clinical examinations was performed during school hours in a well-lit room provided by the school principal, and the students were informed about their rights to refuse.
All occlusal parameters were assessed when the teeth were in maximum intercuspation. Molar relationship was scored subjectively in five half-step units Table 1.Determining Molar Occlusion
Half-step Class II was scored if the mesial aspect of the maxillary first molar was flush with the mesial aspect of mandibular first molar Figure 1a and Half-step Class III was scored if the mesiobuccal step of the maxillary first molar occluded with distobuccal groove or distal cusp of the mandibular first molar Figure 1b. This article reports the two-phase treatment of a female patient, aged 12 years, with an Angle Class III, subdivision right malocclusion with anterior crossbite in maximum intercuspation MIC and end-on bite in centric relation, further presenting with lack of maxillary space.
The case was treated without extractions and with growth control. She had no sucking or postural habit and had normal swallowing and speech.
She was in the permanent dentition phase with second maxillary molars still missing. Menarche had occurred five months earlier, suggesting that the patient was in the deceleration phase of pubertal growth spurt.
She had no relevant carious lesions and no periodontal problems. In centric relation CR she presented with an end-on bite in the anterior region, and maximum intercuspation MICsevere anterior crossbite Figs 12 and 3.
In researching the family history it was found that the mother had an end-on dental relation in the anterior region. The patient's chief complaint was esthetics-related. According to her, she was greatly disturbed by the protrusion of her lower teeth.
From a dental perspective, she presented,in CR, an Angle Class III malocclusion, right subdivision, end-on incisor relationship and, on the right side, bilateral posterior open bite, maxillary and mandibular crowding with rotations, lack of space for tooth 13 with slight impingement, permanence of tooth 53 and midline shift greater than 3.
The analysis of periapical radiographs revealed the presence of all permanent teeth, in addition to tooth 53, and the early formation of third molars. No changes capable of compromising orthodontic treatment were found Fig 4. It is noteworthy that these values were influenced by the end-on relation of the incisors during projection in CR. The cephalometric measurements can be evaluated in Table 1. As regards the dental aspects, space was required for the correction of crowding, rotations and midline.
The purpose was to maintain the inclination of maxillary incisors and enhance lower incisor inclination buccally, as well as achieve appropriate canine and molar relationships. From a skeletal standpoint, the aim was to reduce the anteroposterior discrepancy by maxillary protraction and redirection of mandibular growth with the purpose of enabling a more harmonious growth, expanding the upper arch and controlling the vertical direction of growth. In the first phase, a removable "Skyhook" type appliance g would be used in conjunction with a Hyrax-type palatal expansion appliance with two daily activations to correct the crossbite.
In addition to the expander, brackets would be bonded to the upper incisors Roth prescription, 0. In the second phase, the expander would be removed and a chin cup prescribed for night use.
The complete fixed orthodontic appliance would be set up to proceed with alignment and leveling using 0. If necessary, from the moment archwire progression reached 0. After the end of active treatment, a 0.
incisor relationship - oi
The patient and her parents were also informed in writing of the need for careful hygiene and proper care of the appliances to ensure the normal development of treatment and retention.
The Hyrax-type appliance was installed with two buccal extensions in the canine region for attachment of the protraction elastics, with a recommendation of two daily activations 0. Expansion proceeded as expected and after ten days of activation the screw was stabilized. After 21 days, Roth prescription straight wire metal brackets were bonded to the maxillary incisors for leveling and alignment while creating space for tooth Six months later, the expander and protraction appliance were removed.
The patient's anterior and posterior crossbites were corrected, along with the dental Class III.