Open-Bite Malocclusion
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Open-Bite Malocclusion

Treatment and Stability

Guilherme Janson, Fabricio Valarelli, Guilherme Janson, Fabricio Valarelli

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eBook - ePub

Open-Bite Malocclusion

Treatment and Stability

Guilherme Janson, Fabricio Valarelli, Guilherme Janson, Fabricio Valarelli

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Open-Bite Malocclusion: Treatment and Stability presents the etiology, treatment, and its stability of anterior open bite malocclusion in the early, mixed, and permanent dentitions. Special emphasis is devoted to orthodontic treatment and its stability in the permanent dentition because this is the time when treatment of open bite presents greater relapse. Appropriate for clinicians, orthodontic residents, and dental students, Open-Bite Malocclusion covers the most simple treatment approaches to the most complex, from orthodontic devices to tooth extraction to surgery.

Unique to this book is the discussion of post-treatment stability. Drs. Janson and Valarelli highlight the post-treatment changes and presents strategies to increase treatment stability. This allows the clinician to be able to predict the stability probabilities when treating anterior open bite malocclusions in the permanent dentition either with or without extraction, orthodontic-surgical therapy, or with occlusal adjustment.

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Etiology of open-bite malocclusion
Karina Freitas and Rodrigo Cançado
Anterior open-bite malocclusion is defined as the absence of contact between the maxillary and mandibular incisor edges consequently presenting a negative overbite (Nielsen 1991; Ngan and Fields 1997). Generally, it deteriorates the facial aspect, impairs mastication and speech, subjecting the patient to uncomfortable situations (Janson et al. 2003). The frequency of this malocclusion in the mixed dentition is high (17% [Worms et al. 1971]), and the prognosis for correction varies from good to deficient, depending on its severity and on the patient's age. Before undertaking any treatment alternative, knowledge of the etiology of this malocclusion is important because in many instances, not only the morphological characteristics have to be corrected, but also the etiological factors have to be eliminated not only to assure treatment success, but also to provide long-lasting stability. Therefore, this chapter covers the most common etiological factors of anterior open-bite to help in managing the correction of this malocclusion in the different stages of the dentition it may present.
The etiologic factors of the malocclusions can be divided into environmental and genetic factors. However, all malocclusions are multifactorial and result from interactions of environment and genetics (Mossey 1999a, 1999b). The face and the dentition are influenced by the complex interaction of both. It can be stated that the etiology of a particular malocclusion is predominantly environmental or genetic, and this will determine how much this malocclusion can be corrected by therapeutic intervention, that is, the prognosis of orthodontic correction. The greater the influence of environmental factors in the etiology of a malocclusion, the better the orthodontic treatment prognosis, as long as the causative factor is eliminated. When there is a strong genetic etiologic factor, most likely the best approach would consist in an orthodontic-surgical approach (Beane 1999). Because environmental open bites are more amenable to an orthodontic approach, this chapter will first cover the environmental etiologic factors and secondly the genetic factors.

Environmental Factors

Anterior open bite can be considered as functional consequent to its functional etiologic factors. The most important functional factors are deleterious oral habits, (Popovich and Thompson 1973; Mahalski and Stanton 1992; Johnson and Larson 1993) and oral breathing (Proffit and Mason 1975; Lowe and Johnston 1979; Harvold et al. 1981; Linder-Aronson et al. 1986; Nagahara et al. 1996; Yashiro and Takada 1999). Some other factors may contribute in the environmental etiology such as traumatisms and pathologies (Prosterman et al. 1995).

Deleterious habits

In a normal occlusion, there is a balanced relationship among the oral structures, basal bones, teeth, and intra and extraoral musculature, reflecting in a correct function of the stomatognathic system (Moyers 1988). This is denominated the buccinator mechanism. Thus, the teeth are in a balanced position receiving opposing forces arising internally by the tongue and externally by the lips and cheeks (Figure 1.1) (Graber 1966).
Figure 1.1 Balanced forces between the tongue, lips, and cheeks on the teeth and bone structures.
The solution of this muscular balance for some abnormal function of the oral muscles has a negative impact on the teeth position and occlusion. Nonnutritive sucking habits, such as pacifier and thumb-sucking, atypical tongue thrust, and anterior tongue posture, all considered deleterious oral habits, can break this muscular balance.

Pacifier and thumb-sucking

Humans start sucking fingers, tongue, and lips during fetal life, in the maternal womb (Figure 1.2). At birth, the infant has a well-developed function of sucking to receive the nutrients essential for life. It is during suction developed in breastfeeding that the children not only get the nutrients that need to meet the physiological demands, as well as feelings of security, warmth, and acceptance necessary for their welfare and for their proper emotional development. At this stage, suction is a mean of communication of the infant with the environment (Newman 1990).
Figure 1.2 Prenatal thumb-sucking seen in a ultrasonographic examination.
The early well-developed oral perception provides a sense of comfort, safety, and emotional satisfaction during sucking. When breastfeeding is not possible, the use of bottles with orthodontic nipples that resemble the anatomy of a woman's breasts is recommended, because they allow better contact of the tongue with the palate, as necessary for normal swallowing (Graber 1966) (Figure 1.3).
Figure 1.3 Breastfeeding provides the natural need to suck to the child.
When a child is bottle-fed, his physiological demand is met, but the natural need to suck is not supplied in the few minutes spent in the mother's lap. Thus, the child can begin the compensating thumb or pacifier sucking (Graber 1966).
Pacifier or thumb-sucking are considered as mechanisms of emotional supply of the child. Consequently, pacifier or thumb-sucking in the early child development is considered normal. Through these habits, the child releases the emotional tensions from lack of affective care resulting from conflicting relationship between child and parents, which becomes a way to draw attention from people close to them (Moyers 1988). Parental opposition to these habits can determine negative psychological consequences. When children grow and develop other means of communication with the external environment, they usually spontaneously abandon the sucking habit. Interruption of sucking habits during the deciduous dentition can provide self-correction of the anterior open bite. However, persistence of the habit until the mixed dentition represents a deviation from normality, because these habits are potent etiologic malocclusion factors, particularly for anterior open bite (Ogaard et al. 1994; Bishara et al. 2006).
Pacifier or thumb-sucking act as mechanical obstacles, preventing eruption of the anterior teeth and establishing an open bite (Moyers 1988; Proffit et al. 2007) (Figure 1.4). Anterior open-bite malocclusion due to pacifier use is characteristically restricted to the anterior teeth and circular (Figure 1.5). Anterior open bite consequent to thumb-sucking is characterized by labial inclination of spaced maxillary incisors and lingual inclination of the mandibular incisors (Figure 1.6). Anterior open bite may be associated to maxillary constriction and uni- or bilateral posterior crossbite, because, during sucking, the tongue is lowered, without contact with the maxillary posterior teeth (Moore 1996).
Figure 1.4 Pacifier and thumb-sucking are strong etiologic factors for open-bite malocclusion.
Figure 1.5 Anterior open bite caused by the use of pacifier is characterized by being restricted to the anterior region of the dental arches and circular.
Figure 1.6 Thumb-sucking characteristically causes labial inclination of the maxillary incisors and lingual inclination of the mandibular incisors.
However, a deleterious oral habit does not always necessarily results in an open bite. First, it depends on how the habit is exercised, that is, it depends on the duration (for how long it is exercised, e.g., for how long the child keeps the pacifier in position), on the frequency (number of times per day it is exercised), and on the intensity (the amount of force developed by the habit) of the habit. These factors are important in the etiology of this malocclusion and are known as Graber's Trident (Graber 1958). Besides its mode of action, another important factor in the onset of an anterior open bite is the facial growth pattern. In the presence of deleterious habits, patients with vertical growth pattern have a greater tendency to manifest anterior open bite than patients with horizontal growth pattern (Schendel et al. 1976; Nielsen 1991). Therefore, the manifestation of an open bite depends on the association of environmental (Graber's Trident) and genetic factors (facial growth pattern). This explains why there are children with habits but without an open bite (Figure 1.7).
Figure 1.7 Child with thumb-sucking habit, but without open bite, demonstrating that the malocclusion is dependent on Graber's trident and on patients growth pattern.
Prevention requires that intervention of thumb-sucking habit is started as soon as possible. Several studies (Graber 1966; Moore 1996; Vadiakas et al. 1998) have suggested the use of orthodontic pacifiers as a preventive step in thumb-sucking habit, based on findings that pacifier habit tends to be discontinued earlier than thumb-sucking habit.

Anterior tongue pos...

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