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Long-term stability of the correction of the unilateral posterior crossbite [Elektronische Ressource] / vorgelegt von Theodosia N. Bartzela

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115 pages
Aus der Universitätsklinik für Zahn-, Mund- und Kieferheilkunde der Albert-Ludwigs-Universität Freiburg i. Br. Abteilung für KieferorthopädieLong – Term Stability of the Correction of the Unilateral Posterior Crossbite INAUGURAL – DISSERTATION zu Erlangung des Zahnmedizinischen Doktorgrades der Medizinischen Fakultät der Albert-Ludwigs-Universität Freiburg i. Br. Vorgelegt 2004 von Theodosia N. Bartzela geboren in Patras, Griechenland Dekan: Prof. Dr. J. Zentner 1. Gutachter: Prof. Dr. I. E. Jonas2. Gutachter: Prof. Dr. J. R. StrubJahr der Promotion: 2004 Table of contents_______________________________________________1. INTRODUCTION………………………………………………………...1 2. LITERATURE REVIEW………………………………….....13 2.1 Treatment response………………………………………………..13 2.2 Growth limitations…………………………………………………13 2.3 Relapse…………………………………………………...14 2.4 Open bite…………………………………………………17 3. AIM OF THE STUDY……………………………..……………….……19 4. SUBJECTS AND METHODS…………………………….….20 4.1 Subjects…………………………………………………….……..20 4.2.1 Methods………………………….……….….23 4.2.2 PAR Index……………………………………………….………..26 4.2.3 Cephalometric measurements……………………….…………..28 4.3 Statistical methods……………………………………………….30 5. RESULTS…………………………………………….………...31 5.1 Assessment of method of odontometric meassurements…….…....31 5.2 Mean ages and mean observation period………….……………....32 5.3 PAR Index……………………………………………….….……….33 5.4 Arch width changes……………………………….……...35 5.
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Aus der Universitätsklinik für Zahn-, Mund- und Kieferheilkunde
der Albert-Ludwigs-Universität Freiburg i. Br.
Abteilung für Kieferorthopädie
Long – Term Stability of the Correction of the Unilateral
Posterior Crossbite
INAUGURAL – DISSERTATION
zu
Erlangung des
Zahnmedizinischen Doktorgrades
der Medizinischen Fakultät
der Albert-Ludwigs-Universität
Freiburg i. Br.
Vorgelegt 2004
von Theodosia N. Bartzela
geboren in Patras, Griechenland Dekan: Prof. Dr. J. Zentner
1. Gutachter: Prof. Dr. I. E. Jonas
2. Gutachter: Prof. Dr. J. R. Strub
Jahr der Promotion: 2004 Table of contents_______________________________________________
1. INTRODUCTION………………………………………………………...1
2. LITERATURE REVIEW………………………………….....13
2.1 Treatment response………………………………………………..13
2.2 Growth limitations…………………………………………………13
2.3 Relapse…………………………………………………...14
2.4 Open bite…………………………………………………17
3. AIM OF THE STUDY……………………………..……………….……19
4. SUBJECTS AND METHODS…………………………….….20
4.1 Subjects…………………………………………………….……..20
4.2.1 Methods………………………….……….….23
4.2.2 PAR Index……………………………………………….………..26
4.2.3 Cephalometric measurements……………………….…………..28
4.3 Statistical methods……………………………………………….30
5. RESULTS…………………………………………….………...31
5.1 Assessment of method of odontometric meassurements…….…....31
5.2 Mean ages and mean observation period………….……………....32
5.3 PAR Index……………………………………………….….……….33
5.4 Arch width changes……………………………….……...35
5.5 Tables of maxillary changes………………………………….……..58
5.6 Tables of mandibular changes……………………….…..61
5.7 Frontal overbite……………………………………………………..64
5.8 Overjet……………………………………….....66
5.9 Mandibular midline deviation……………………………………...68
5.10 Skeletal growth pattern…………………….....70
5.11 Skeletal classification……………………………………………….71
6. DISCUSSION………………………………………..72
6.1 Discussion of the materials…………………………………………...72 6.2 Discussion of the results……………………………………………79
7. CONCLUSIONS…………………………………..89
8. SUMMARY……………………………………………………………..90
9. ZUSAMMENFASSUNG………………………….91
10. REFERENCES…………………………………………………………92
11. CURRICULUM VITAE…………………………109
12. ACKNOWLEDGMENTS……………………………………………. 111 Introduction 1
1. Introduction
The prevalence of posterior crossbite in the early mixed dentition, varies between 8 and 23%
according to epidemiological studies, (Ingervall et al., 1972; Magnusson, 1976; Garner and
Butt, 1985; Kurol et al., 1992; Lew et al., 1993; Johannsdottir et al., 1997; Jämsä et al., 1997;
Thilander, 2001; Thilander and Lennartsson 2002). In white American children it is
approximately 7%, (Kutin and Hawes, 1969; Infante, 1975). The incidence is higher in
European children at 13-23% (Kisling, 1981; Kurol and Berglund, 1992) and lower in Afro-
American children at 1-2% (Infante, 1975; Kerosuo, 1990). It has been stated that posterior
crossbite appears at a fairly constant rate in different malocclusions and at different ages. This
implies that this abnormality develops early and is not self- correcting (Thilander, 1984).
In previous publications, the crossbite anomaly has been associated with a narrow upper
dental arch. Unilateral crossbite is characterized not only by an arch deficiency but sometimes
by asymmetries, in the upper or the lower arch or in both (Thilander and Lennartsson, 2002).
The higher the number of teeth included in the crossbite malocclusion, the more obvious it is
that a skeletal component is included (Solow, 1980). Maxillary transverse deficiency may, in
fact, be one of the most pervasive skeletal problems in the craniofacial region. It is not
surprising that certain types of sagittal malocclusions are also associated with maxillary
deficiency. The signs of maxillary deficiency are such that they often appear together, in what
may be termed a “maxillary deficiency syndrome”.
Crossbite and dental crowding are easily identifiable clinical signs of a maxillary deficiency
(McNamara, 2000). Although such patients appear to have a normal posterior occlusion,
closer inspection reveals an intermolar width of < 31 mm and an accentuated curve of Wilson.
In these cases patients are candidates for rapid maxillary expansion (RME) therapy before
comprehensive edgewise therapy (McNamara, 2000). Other symptoms of the maxillary
deficiency (not so easily identifiable) are lingually flared posterior maxillary and /or buccally
flared posterior mandibular teeth (Solow, 1980).
Moyers (1974) concluded that lack of harmony between maxillary and mandibular widths was
usually due to a bilaterally contracted upper arch, in which case the muscles would shift the
mandible to one side to acquire sufficient occlusal contact for mastication and comfort.
Generally, this mandibular shift is also compensated by adaptations within the neuromuscular
system. This asymmetric muscular activity at rest (without cuspal interferences) may lead to
permanent displacement of the mandible (Hamerling et al., 1991). Depending on the 2 Introduction
functional analysis, two types of lateral mandibular deviation can be differentiated in
unilateral crossbite: laterognathy and lateroclusion.
Lateroclusion: The mandibular midline deviation is observed only in habitual occlusion and
not in the rest position due to tooth guidance. The crossbite in this case is called functional
non-true crossbite and the prognosis for causal therapy is favorable (Rakosi et al.,1993)
(Figs.1, 2).
Laterognathy: In occlusion and in rest position the mandibular midline is not aligned with the
facial midline. A posterior crossbite with laterognathy is called true crossbite and the
prognosis is unfavorable for causal correction by orthodontics and dentofacial orthopaedics.
(Figs.3,4).
Fig. 1: Mandibular midline deviation in occlusal Fig. 2: The mandibular midline is aligned in
position. rest position (lateroclusion).
Fig.3: Mandibular midline deviation in occlusal Fig.4: The mandibular midline deviation persists in
position. . rest position (laterognathy).
Early Treatment or not
Early treatment in orthodontics is controversial with respect to its cost/benefit ratio. In
crossbite cases early treatment has been recommended because spontaneous correction is
unusual (Thilander et al., 1984; Lindner et al., 1986). Introduction 3
However, Kurol and Berglund (1992) found a high rate (up to 45%) of spontaneous correction
at early ages. For this reason they recommended the correction of crossbite malocclusion only
in the early mixed dentition. If this malocclusion is left untreated, skeletal remodeling may
occur over time and the mandibular deviation towards the crossbite side may persist (Bishara
et al., 1994; O’Byrn et al., 1995).
Studies by Lindner (1989) and by Kurol and Berglund (1992) revealed that 50% of the
crossbite cases treated in the primary dentition relapsed or had to be retreated in the early or
late mixed dentition.
In children with unilateral posterior crossbite, it has been documented that the condyles are
relatively malpositioned in their fossae. Increasing maxillary arch width in the correction of
functional posterior crossbites may allow normal vertical mandibular closure patterns and
assist in the establishment of symmetrical temporomandibular joint relationships (Myers et
al., 1980; Pullinger et al., 1985; Hesse et al., 1997;).
It was proven by Okeson (1985) that a medial, anterior, and inferior movement of the condyle
on the noncrossbite side and a lateral, posterior, and superior movement of the condyle on the
crossbite side exist during mandibular closing movement from the open position to the
position of maximum intercuspation.
In addition, some epidemiological studies have shown that TMJ problems are associated with
unilateral crossbites (Jämsä et al., 1988; Thilander, 2001).
In young children the sliding of the mandible from retruded position (RP) to maximal
intercuspal position (IMP) results in asymmetrical EMG activity of the temporal and masseter
muscles. The muscular hyperactivity influences the morphology of the TMJ (Ingervall et al.,
1972).
Moorrees et al. (1969) pointed out that considerable individual variation in arch form will
occur with age due to normal growth. A minimal tendency towards an increase in the
intermolar width during the transition from the deciduous to the permanent dentition was
observed. It is apparent that changes in arch width vary between males and females and that
more growth in width occurs in the upper than the lower arch. This growth, which occurs
mainly between 7 and 12 years of age, is approximately 7-8 mm. According to Björk’s
implant investigation, two thirds of the above measurements are due to sutural growth (Björk
and Skieller, 1984).
According to Gianelly (1995) 90% of all growing patients can be treated successfully in one
single phase by starting treatment in the late mixed dentition stage of development 4 Introduction
(exfoliation of all deciduous teeth except the second primary molars). The other 10% of
patients who can benefit from the early treatment approach are crossbite cases that are
complicated by a mandibular shift and Class III patients.
Crossbite correction in the deciduous dentition allows the eruption of the first permanent
molars in symmetrical occluding dental arches (Thilander and Lennartsson, 2002).
Many studies also support the concept of early treatment of unilateral crossbite in order to
coordinate the asymmetric muscle activity to facilitate a normal intermaxillary relationship
and to avoid craniofacial asymmetry and subsequent TMJ dysfunction. It is commonly
believed that unilateral posterior crossbites are associated with postural problems that may
develop into musculoskeletal problems in adults (Pirttiniemi et al., 1990; Schmid et al., 1991
Mew, 1995).
The later the treatment start of crossbite malocclusions, the greater the risk of the
temporomandibular joint being damaged (Kantomaa, 1988).
Translation movement of the deciduous dentition has been found to affect the position of the
underlying permanent teeth, and early correction of crossbites is thought to encourage
favorable eruption patterns (Barnes, 1956; Cheney, 1959; Wood, 1962; Harvold, 1963; Davis,
1969; Kutin, 1969; Matthews, 1969; Buck, 1970; Clifford, 1971; Bell, 1974; Moyers, 1974;
Kennedy et al., 1976, Ricketts, 1979).
In summary: In addition to the enhanced skeletal response, early crossbite correction may
offer the advantages of redirecting the developing tooth germs into a more normal position,
correcting asymmetries of the condylar position and allowing normal vertical closure of the
mandible without functional shifts.
The main objectives of early treatment lie in 5 concepts:
1. Obtaining a skeletal change (structural).
2. Providing the opportunity for a functional change in the environment.
3. Utilizing the individual growth expression towards the correction.
4. Eliminating habits.
5. Taking advantage of the forces of occlusal development towards the correction
(Ricketts, 2000).
The goals and objectives of treatment must be clearly established to prevent unnecessarily
prolonged treatment that may “burn out” the patient’s cooperation in the future (Graber,
1995). Introduction 5
Treatment approaches: The recommended treatment is expansion of the maxillary dental arch
(Cheney, 1959; Sims, 1972; Moyers, 1974) and elimination of dental interferences. Correction
of posterior crossbites in young patients is accomplished by a combination of skeletal and
dental expansion. Skeletal expansion involves separation of the right and left halves of the
maxilla at the midpalatal suture; dental expansion results from buccal tipping of the maxillary
posterior teeth (Krebs, 1958; Haas, 1961; Wertz, 1970; Melsen, 1972; Cotton, 1978; Hicks,
1978).
The goal of palatal expansion is to maximize skeletal movement and minimize dental
movement, while allowing for physiologic adjustment of the suture during separation (Haas,
1961; Isaacson et al., 1964; Storey, 1973).
Corrective treatment is aimed at facilitating the development of symmetric dental arches and
at establishing a normal intermaxillary occlusion. Narrow upper and broad lower dimensions
will result in failure, if an expansion appliance is used in the upper jaw only, without the
growing lower jaw being treated (Thilander and Lennartsson, 2002).
A moderate increase in dental arch width can be expected in the anterior regions, until the
permanent canines erupt (Moorrees and Reed, 1952; De Kock, 1972).
It is therefore important for dental expansion to be overdone in the interest of improving the
dental base relationships (Haas, 1970).
The dental anchorage units must be made as strong as possible in order to achieve maximum
skeletal expansion and minimum dental compensation.
Treatment options in lateral crossbites in general include:
1. dentofacial orthopedics if the patient is actively growing and it is anticipated that
further growth will be symmetric or
2. dentoalveolar movement if compensation is feasible;
3. orthognathic surgery if the underlying skeletal discrepancy is severe and the patient is
no longer growing (Haas, 1970).
The type of appliance used depends on the amount of expansion desired and the patient`s age.
Initial changes involve lateral tipping of the posterior maxillary teeth as the periodontal and
palatal soft tissues are compressed and stretched respectively. If the applied transverse forces
are of sufficient magnitude to overcome the bioelastic strength of sutural elements, orthopedic
separation of the maxillary segments can occur (Storey, 1955; Isaacson and Ingram, 1964;
Cleall, 1965; Murray and Cleall 1971; Brossman et al., 1973; Storey, 1973; Cotton, 1978;
Hicks, 1978) 6 Introduction
The removable expansion appliance with a jackscrew as an activating element must be
sufficiently anchored to the teeth to give the device the stability that is needed to create
efficient orthopedic results. Incremental activations produce an inherent instability of the
appliance and lessen the effective force required to produce maxillary expansion (Chaconas
and Caputo, 1982).
Slow maxillary expansion with a fixed split acrylic appliance was evaluated by Hicks (1978)
with the use of frontal and lateral cephalograms. The results of his measurements showed that
the linear arch width changes were due to bodily translation of the teeth and the maxillary
segments.
The slow expansion procedure allows a more physiologic sutural tissue integrity,
repositioning and remodeling than rapid maxillary appliance application (Storey, 1973;
Ekström et al., 1977; Cotton, 1978).
Reduced skeletal relapse tendency was also observed in the slow maxillary expansion cases
due to reduced stress within the involved tissues and in maintenance because of the sutural
integrity (Storey, 1973; Cotton, 1978; Mossaz- Joelson and Mossaz, 1989).
Storey (1978) and Ekström (1977) showed that the slow expansion procedure allows
physiologic adjustment of the midpalatal suture within 30 days.
Slow maxillary expansion (= activation of the expansion screw 1x per week) is the treatment
of choice of many practitioners because the lower forces applied cause less sutural trauma and
less dental tipping, making for greater stability, and less relapse potential during the
organization of the maxillary complex (Bell, 1982).
Hicks (1978) reported substantial orthopedic changes with slow expansion techniques in
early-treatment groups.
The graphs show the rates of skeletal and dental movement in slow (Fig. 5) and rapid (Fig. 6)
maxillary expansion in a treatment course of 10 weeks according to Hicks (1978). In the slow
expansion group, the dental- skeletal expansion rate is 1:1. The plot graph illustrates that in
the 10-week period the expansion rate would consist of 5 mm of dental and 5 mm of skeletal
expansion (Hicks, 1978).
In the RME group the plot (Fig. 6) shows at the beginning of treatment mainly a skeletal
component, which constantly decreases with time. The dental component of the movement is
rather low at the beginning but increases with treatment time. After 4 weeks the skeletal and
dental components are equal (Hicks, 1978).

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