Results. The flush terminal plane molar relation (%) was the most common primary molar relation. The distal step molar relation was more. molars seems to be the most significant determinants of occlusal develop- ment in molar relationship common to Normal occlu- sions and Class I. molar relationship was the most common (30%) type of malocclusion. . cranial base in the deciduous dentition, found no difference between Class II children.
In this review, we focused on skeletal malocclusion that affects We summarized the prevalence of class I, II and III of malocclusion in different ethnic groups and discussed the most frequent medical disorders associated with skeletal malocclusion.
Dental anomalies that lead to malocclusion such as tooth agenesis, crowding, missing teeth and abnormal tooth size are not addressed in this review. We propose a modified version of malocclusion classification for research purposes to exhibit a clear distinction between skeletal vs. In addition, we performed a cross-sectional analysis on orthodontic malocclusion data through the BigMouth Dental Data Repository to calculate potential association between malocclusion with other medical conditions.
In conclusion, this review emphasizes the need to identify genetic and environmental factors that cause or contribute risk to skeletal malocclusion and the possible association with other medical conditions to improve assessment, prognosis and therapeutic approaches.
Skeletal malocclusion, Micrognathia, Retrognathia, Prognathia, Late-onset diseases Introduction Disorders of the head and face are very common birth defects in all racial populations, and can appear as isolated phenotype or as part of a syndrome. The prevalence of craniofacial anomalies varies among different ethnicities based on genetic background, geography, socio-economical status and environmental factors.
Because of the structural complexity of the craniofacial region, variations in genetic and environmental factors may have a profound effect on development, and could lead to congenital birth defects.
- Skeletal Malocclusion: A Developmental Disorder With a Life-Long Morbidity
Cleft lip and palate is one of the most common birth defects with the highest prevalence of 1 in live births in Asian population [ 1 ]. It has been reported that all patients with micrognathia are also affected with retrognathia abnormal posterior positioning of the mandible or maxilla relative to the facial structure due to the small size and growth pattern [ 3 ].
On the other hand, macrognathia is characterized by the overgrowth of the mandible or maxilla above the normal values where the manifestation becomes more prominent at the peak of jaw growth around the age of Sonographic detection used for prenatal diagnosis of isolated micrognathia manifestation of class II malocclusion is normally disparate from the actual natal outcome in the large majority of cases.
This is due to the small size of the mandible that causes the tongue to stick to the roof of the mouth and prevent the appropriate downward vertical growth, elevation and fusion of the secondary palatal shelves. The clefts of the soft and hard palate in these cases have the characteristic feature of the U or V shape clefting indicating a complete obstruction of secondary palatal development. Other studies have argued that isolated micrognathia is a harbinger of severe diseases in humans [ 5 ].
An ideal overjet was observed among The evaluation of overbite showed that Similar trend of prevalence was observed among both the sexes with respect to overjet and overbite. Statistical significant difference was found among the sexes with respect to overjet while no significance was found with regard to overbite. Distribution of overjet variations.
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Distribution of overbite variations. The most frequent site of spacing Table 5 in the maxillary arch coincided with the anthropoid space between the lateral incisor and canine The spaces greater than or equal to 2 mm were found most commonly in relation to maxillary primate spaces 1.
The sites of contact of teeth were found most frequently between first and second primary molar in both maxilla Arch wise prevalence of spacing. Statistical significant difference was found between the sexes Table 6 with respect to spaces between first molar and caninecanine and lateral incisorand central and lateral incisor. Arch wise and gender wise prevalence of spacing. Discussion The occlusion of the primary dentition is completely established by the age of 3 years and lasts until about 6 years of age when the first permanent tooth begins to erupt [ 11 ].
Understanding the association between morphological aspects in the primary dentition and its transition to the permanent dentition provides the possibility of predicting the final permanent occlusion [ 12 ].
Skeletal Malocclusion: A Developmental Disorder With a Life-Long Morbidity
The anteroposterior relation of maxillary and mandibular permanent molars is an important criterion for recognition of malocclusions. This determines the necessity of interceptive orthodontics. The flush terminal plane in the primary dentition is the most predominant primary molar relation followed by mesial and distal step [ 561113 — 18 ] and similar trend was noticed in our study.
The flush terminal plane relation was frequently found in our population Analogous observations were reported in Finnish and Iranian children [ 2021 ]. The flush terminal plane was found to be the most common molar relation and considered ideal for transition to class 1 in permanent dentition. However, mesial step was found to be the norm for completed primary dentition rather than flush terminal plane [ 22 — 24 ].
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Since flush terminal plane was the most common molar relationship in the present study we anticipate that the majority of the sample may have a favorable permanent molar relation. The findings of the present study showed that These findings were similar to the previous studies conducted in different populations [ 4111416171925 ]. Contradictory findings were reported in Finnish children among whom class II relation Canine and molar relationship together can be a diagnostic aid to predict changes in occlusal relationship.
In clinical situations like flush terminal plane with class II canine relationship indicates a higher risk to develop a distal occlusion in permanent dentition.
Therefore both the molar and canine relationships are taken into consideration to make a reliable prediction of the intermaxillary relationship in the permanent dentition [ 20 ]. The results of our investigation revealed ideal overjet in This finding is consistent with Nigerian children who demonstrated ideal overjet in Majority of Saudi and Chinese children had ideal overjet as seen in the present study [ 1126 ].
An ideal overbite was found in These findings were akin to those reported in Saudi Arabian children [ 11 ]. A study in Jordanian population demonstrated overbite in Increased open bite could be attributed to oral habits such as dummy sucking and finger sucking [ 5 ]. Presently, no data indicates a definitive threshold value for overbite or overjet that could be applied in early diagnostics [ 20 ].
The higher prevalence of ideal overjet and overbite observed in our population may be conducive to achieve ideal anterior relation in permanent dentition. Spaces in the primary teeth are described as physiological or developmental spaces. The spacing around the canines is termed as the simian gap [ 6 ], primate space [ 13 ], or anthropoid space [ 9 ], since they are prominent in dentitions of certain lower primates.
Based on spacing between the teeth, Baume has classified the arrangement of primary dentition into two forms: Anterior spacing appears to be a common finding in our study population. Primate spaces were frequently found in the maxilla than mandible [ 372930 ] as observed in the present study. Male children demonstrated more frequency of primate spaces than females both in the maxilla and mandible.
In contrast, primate spaces did not show significant difference between the genders in Tehran and Saudi children [ 2131 ]. Extreme spacing of 2 mm in our study was associated with anthropoid spaces in the maxilla 1.
The incidence of crowding or overlapping of teeth in our sample was more prevalent in the mandible than in the maxilla.
In mandible, crowding was predominant between the lateral incisor and canine 9. This study illustrated that crowding was more prevalent in females than in males in both maxilla and mandible. Majority of the study population demonstrated spaced arches which would lead to favorable permanent occlusion. Conclusion Occlusal characteristics vary among populations. To summarize, flush terminal plane, class I canine relation, ideal overjet, ideal overbite, and spaced arches prevailed among majority of the study population without any gender variations.
These findings suggest favorable occlusal characteristics and spacing in primary dentition. However, future longitudinal studies are needed to observe whether the transition of these occlusal characteristics will lead to favorable occlusion in the permanent dentition.
Chandrasekhar and Vinay Chandrappa are coauthors.