Journal of Indian Society of Pedodontics and Preventive Dentistry
Journal of Indian Society of Pedodontics and Preventive Dentistry
                                                   Official journal of the Indian Society of Pedodontics and Preventive Dentistry                           
Year : 2005  |  Volume : 23  |  Issue : 2  |  Page : 63--66

Cephalometric evaluation of class-III patients with chin cap and tongue guard

SM Danaie, P Salehi 
 Department of Orthodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran

Correspondence Address:
S M Danaie
Department of Orthodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz


The purpose of this study was to determine the effect of chin cap therapy combined with an upper tongue guard in the early treatment of class-III malocclusion on the nasomaxillary complex and mandible. The subjects of this study consisted of 40 patients aged 5-13 years (mean age of 8.5 2). All of them possessed an anterior cross bite and/or concave profile. The mean force of chin cap was determined to be 200 g on each side for 18 h/day and the mean treatment period was 22 months. The cephalometric analyses including skeletal, dental, and soft tissue analysis were carried out before and after treatment. The analysis of the cephalometric measurements revealed a negative correlation between the combination effects of chin cap therapy upper tongue guard. This effect appeared in the early stages of treatment. It was a case-control study and Wilcoxon test was used for statistical analysis. The comparison of dependent variables revealed that skeletal effects of chin cap therapy were more than dental and soft tissue effects. Changes in the upper and lower pharyngeal spaces were not significant. A reduction of nasolabial angle occurred due to the protrusion of upper incisors. Finally, it was shown that the combination of chin cap and upper tongue guard could be more effective in the early treatment.

How to cite this article:
Danaie S M, Salehi P. Cephalometric evaluation of class-III patients with chin cap and tongue guard.J Indian Soc Pedod Prev Dent 2005;23:63-66

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Danaie S M, Salehi P. Cephalometric evaluation of class-III patients with chin cap and tongue guard. J Indian Soc Pedod Prev Dent [serial online] 2005 [cited 2020 Oct 29 ];23:63-66
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Full Text

Chin cap therapy has been widely used for the treatment of class-III malocclusion for many years. It has been shown through several clinical[1],[2] and experimental studies[3],[4] that the chin cap force is definitely effective on the growing mandible. In case of severe malocclusion, orthognathic surgery is recommended. However, a complete inhibition of mandibular growth seems to be difficult to achieve through the use of the chin cap appliance in human.[5] Abu Alhaja and Richardson emphasized the difficulty of inhibition of mandibular growth.[6] Wendel and Nanda considered the chin cap as a viable mode of treatment for patients with true, mild to moderate pre-adolescent mandibluar prognathism.[7] Graber [1] and Rittuci and Nanda[8] reported that chin cap therapy had no effect on the anteroposterior maxillary growth. Conversely, Sugawara et al[9] stated that no significant difference in the skeletal profile was observed after the application of the chin cap to two different groups of patients starting treatment at the ages of 7 and 11 years. But at the age of 17, the mid-face was more deficient in patients in the control groups than in those of the treatment groups. Oktay et al[5] pointed out that early treatment of anterior cross bite could prevent retarded anteroposterior maxillary growth.

This study was performed to evaluate the effects of 22 months of chin cap therapy and its side effects in relation to the age of the patients and also the continual effects of treatment after improving the profile.

 Materials and Methods

Forty patients referring for treatment to the Orthodontic Clinic of Shiraz Faculty of Dentistry received a chin cap and removable tongue guard appliance. The subjects, presented with an anterior cross bite and straight or concave profile with mandibular prognathism and maxillary retrognathism, and were divided into two groups according to the age of treatment.

Group 1 consisted of 29 patients (5-9 years old), and Group 2 consisted of 11 patients (10-13 years old). Conventional radiography (OPG and lateral cephalometry) was undertaken in the beginning of the study (T1). All the patients wore a chin cap and an appliance with tongue guard. The chin cap applied a total force of 400 g. The direction of the force was laid between gnathion and condyles. Patients were instructed to wear the chin cap and upper appliance for at least 18 h per day. At the end of 22 months of treatment, a normal jaw relationship was obtained with an adequate overbite and overjet. At this time, a second lateral cephalometric radiography was performed (T2).

Eight angular and six-dimensional measurements according to Steiner, McNamara and Wit's appraisal[10],[11],[12] were carried out on the cephalometric radiographs [Figure 1] and [Figure 2]. The difference between before and after linear and angular measurements was defined as a variable. Independent variables (gender, age, treatment period) and dependent variables (skeletal, dental, soft tissue) were also determined.


The comparison of the results relating to the skeletal class III cases is shown in [Table 1] and [Table 2].

In the sagittal direction, growth modification during treatment was obvious in both groups on the Wit's appraisal, SNA, SNB, ANB, Co-Gn, Go Gn-SN, IMPA, LAFH and lower pharynx with the highest change on LAFH ( PV = 0.003) and the lowest on the lower pharynx ( PV = 0.049). Lower pharynx changes were not significant in both genders.

In Group 1, the upper pharynx ( PV = 0.05) and in Group 2, IMPA and facial angle ( PV = 0.05) showed the least significance. However, the changes in treatment period tended to be more significant on all the variables especially on IMPA and facial angle in the patients having longer treatment period.


The comparison between dental, skeletal and soft tissue variables [Table 1] revealed more skeletal changes than the others, so they were considered valid showing the skeletal nature of the therapeutic effect of the chin cap. The comparison of the data between 5-9-years old and 10-13-years old age groups showed skeletal changes especially in the younger group. These findings confirmed one of the hypotheses of the study (the reverse relationship between chin cap effect and patient's age) which is comparable to the study of Sakomoto et al.[13] He observed more backward position of the mandible in the group of early treatment. He also reported[14] more efficiency of chin cap in the younger patients, and that the skeletal changes were limited to the ages above 9 years, so that skeletal imbalances would be compensated by dental movements.

The results of this study confirmed the research carried out by Graber's[1] and Suguwara and Mitani's,[1],[15] concerning the effect of patient's age on chin cap therapy. Their results showed more efficiency of chin cap before growth spurt. So, chin cap therapy after puberty did not generate the beauty profile.

The comparison of the data between the groups with different treatment durations (less and more than 22 months) showed more effects of chin cap on the patients with shorter treatment time. So, it can be concluded that chin cap was more effective at early stages of treatment and lengthening the treatment time did not lead to more positive results.

The decrease of SNB angle and the increase of ANB angle showed the chin cap effect on horizontal growth of the mandible and its downward-backward rotation. This is in accordance with the study carried out by Ucucu and Ucem.[16]

The multivariable regression test showed the correlation coefficient of SNA and SNB angles to be 41%. Also, the slope of regression line between these two variables was B = 41%, which depicted the opposite effect of chin cap on these two angles. It means that for every one degree increase of Pv = 0.01) in most groups revealed more growth of the midface and also indicated that the decrease of vermillion part thickness as a result of chin cap therapy would be neutralized. Moreover, another factor in decreasing of nasolabial, angle is maxillary incisor protrusions as a result of the combination use of chin cap and upper removable appliance. Correction of protrusive profile has already been reported in the studies of Sugawara and Mitani,[15] Wendel and Nanda[7] and Mitani.[17]

The decrease of the IMPA angle was observed in all of the groups, but it was significant only in the 5-9-years old and 10-13-year old males. This decrease represented the dental changes of chin cap therapy. Thailander[18] also reported the lower incisor's linguoversion as an important result of chin cap therapy.

Effective length of the maxilla and mandible and lower anterior facial height were increased in all the groups. This is the result of continuing normal growth of the two jaws and downward-backward rotation of the mandible.

Upper and lower pharyngeal spaces were measured for evaluation of the breathing and tongue position, respectively. These two can both be the etiologic factors for class-III malocclusion. The upper pharynx was increased in all of the groups but not significantly. The lower pharynx was also not significantly decreased in most of the groups. This decrease can be related to the tongue position changes after treatment. This variable and LAFH changes showed a significant correlation ( Pv = 0.007). The mandibular rotation and backward position of the tongue can explain these results. One of the measuring limits of the lower pharynx was the intersection of posterior and inferior borders of the mandible. The significant increase (2.8 mm) of LAFH in all of the patients ( PV = 0) depicted that the force application to the condyle rotates the chin in a downward-backward direction. Backward rotation of the mandible led to more extrusion of the teeth and increase of the facial height. These are comparable to the results of Yoshida et al, Ishikawa et al and Arun and Everdin studies.[19],[20],[21]

The results of this study revealed that in the presence of downward mandibular growth, lower jaw moved to the posterior part, after chin cap therapy. However, in patients with forward mandibular growth, profile improvement cannot be observed, following chin cap therapy. Graber[1] also concluded that this treatment was more effective in horizontally growing patients.

The negative correlation between the combination effect of chin cap therapy and tongue guard with age showed that more skeletal improvement was obtained in early treatment. Applying chin cap treatment in patients aged 5-9 years showed more skeletal effects. It was noteworthy noticeable that it appeared in the early stages of treatment.

Significant changes on


The authors would like to thank the Office of Vice Chancellor for Research of Shiraz University of Medical Sciences for Financial support and Dr. Davood Mehrabani and Center for Development of Clinical Studies for editorial assistance.


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