|Year : 2015 | Volume
| Issue : 2 | Page : 96-103
Reliability of frontal sinus with that of maxillary sinus in assessment of different types of skeletal malocclusions
Indu Dhiman1, Anil Singla2, Vivek Mahajan3, Harupinder Singh Jaj3, Vishal Seth4, Priyanka Negi4
1 PG Student, Department of Orthodontics and Dentofacial Orthopaedics, Himachal Dental College, Sundernagar, Himachal Pradesh, India
2 Prof. and HOD, Department of Orthodontics and Dentofacial Orthopaedics, Himachal Dental College, Sundernagar, Himachal Pradesh, India
3 Reader, Department of Orthodontics and Dentofacial Orthopaedics, Himachal Dental College, Sundernagar, Himachal Pradesh, India
4 Senior Lecturer, Department of Orthodontics and Dentofacial Orthopaedics, Himachal Dental College, Sundernagar, Himachal Pradesh, India
|Date of Submission||24-Mar-2014|
|Date of Acceptance||19-May-2015|
|Date of Web Publication||5-Aug-2015|
PG Student, Department of Orthodontics and Dentofacial Orthopaedics, Himachal Dental College, Sundernagar, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Paranasal sinus plays an important role in the formation of facial contours. Therefore, knowledge of the development and size of the maxillary sinus and frontal sinus may be crucial for diagnosing and treating various classes of malocclusion. Aim: To evaluate the reliability of frontal sinus with that of maxillary sinus in the assessment of different types of skeletal malocclusions. Settings and Design: Sample consisted of lateral cephalograms of 240 patients with three different skeletal malocclusions. Material and Methods: The sample for the study consists of 240 patients (120 males and 120 females) with age of the subjects ranging from 16 to 25 years divided into skeletal Class I, II, and III on the basis of ANB angle (each 40 patients). Linear and angular cephalometric measurements were assessed and correlate with maxillary and frontal sinus size, which is obtained through AutoCAD program. Statistical Analysis: Pearson's correlation coefficient used. Results: The results show a significant correlation of frontal sinus with skeletal malocclusion (P < 0.05) as compared to the maxillary sinus. Conclusions: (1) Frontal sinus is more reliable as compared to maxillary sinus in depicting skeletal malocclusion. (2) Frontal sinus area larger in skeletal Class III malocclusion as compared to skeletal Class I and Class II malocclusion. (3) There is no significant variation in maxillary sinus area in males and females whereas frontal sinus shows significant variations in both males and females in different skeletal malocclusions.
Keywords: Cephalometrics, frontal sinus, maxillary sinus, reliability
|How to cite this article:|
Dhiman I, Singla A, Mahajan V, Jaj HS, Seth V, Negi P. Reliability of frontal sinus with that of maxillary sinus in assessment of different types of skeletal malocclusions. J Indian Orthod Soc 2015;49:96-103
|How to cite this URL:|
Dhiman I, Singla A, Mahajan V, Jaj HS, Seth V, Negi P. Reliability of frontal sinus with that of maxillary sinus in assessment of different types of skeletal malocclusions. J Indian Orthod Soc [serial online] 2015 [cited 2019 Feb 21];49:96-103. Available from: http://www.jios.in/text.asp?2015/49/2/96/162265
| Introduction|| |
Lateral cephalograms have become a vital tool in orthodontic assessment and treatment planning since the introduction of radiography by Broadbent in 1931. ,,, Various anatomical points are used in assessment of different malocclusions which can be precisely and accurately depicted in a lateral cephalogram but presently different other points are also derived which are used to reach definite point of diagnosis in orthodontics. , One of these landmarks are the paranasal sinuses which can be easily assessed by radiographic method like lateral cephalogram, panoramic radiographic view, but lateral cephalogram is more preferred since other radiographs provide duplicate information.  Paranasal sinuses are the bony chambers embedded in the bones around the mid facial structure.  Maxillary sinus, ethmoidal sinus, frontal sinus, and sphenoidal sinus are the four anatomical sinus present in the human body. Of these, maxillary sinus and frontal sinus can be depicted in the lateral cephalogram of almost all the patients.
Development and growth of these sinuses effect different orthodontic malocclusion is hypothesized in different studies.  Maxillary sinus which lies in close proximity to the maxillary posterior teeth might be affected by different skeletal malocclusions.  Similarly, Rossouw et al. found enlarged frontal sinus in subjects having prognathism.  Increase in the bone growth follows same growth pattern in paranasal sinuses.  Different studies have done to investigate paranasal sinus development in patients by lateral cephalograms.
Till date, research has been done to relate paranasal sinus with Class III malocclusions or to predict growth through the use of dry skull,  panoramic radiography,  cone-beam computed tomography, ,, magnetic resonance and lateral cephalogram , but rarely discussed aspect is which paranasal sinus of mid face better assessed the skeletal malocclusion. Hence, the objective of the study was to investigate the reliability of frontal sinus with that of maxillary sinus in the assessment of different types of skeletal malocclusions.
| Materials and Methods|| |
This study was conducted on subjects with age ranging from 16 to 25 years.
The inclusion criteria were as follows:
Two hundred and forty patients (120 males and 120 females) were divided into three groups, each group consists of 40 patients depending on the different types of skeletal malocclusion based on the ANB angle  as follows:
- No previous orthodontic treatment
- No previous history of orthodontic, orthopedic or facial orthodontic treatment
- Fully erupted permanent dentition
- Symmetrical faces
- No paranasal sinuses pathology
- No apparent facial disharmony or cleft lip and palate
- Radiographs of good quality which had clearest reproduction of paranasal sinuses (frontal and maxillary sinus).
Lateral cephalogram was taken for each subject, and each individual was positioned in the cephalostat with the sagittal plane of the head vertical, the Frankfort plane horizontal teeth in centric relation with head rest in natural head position. On the obtained radiograph, frontal sinus, maxillary sinus, and cephalometric landmarks used in the study were traced with the help of 0.5 lead pencil as shown in [Figure 1] and [Figure 2]. Every traced radiograph is then scanned via scanner, and the area of maxillary and frontal sinuses is calculated with the help of AutoCAD program (2010) in mm2 as shown in [Figure 3].
- ANB angle between 2° and 4° (skeletal Class I)
- ANB >4° (skeletal Class II)
- ANB <2° (skeletal Class III).
|Figure 3: Lateral cephalometric image showing with measurements done on AutoCAD software|
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The following reference points and cephalometric variables were examined in the study are as follows:
Reference points [Figure 1]:
Cephalometric variables examined in the study [Figure 2]:
- N - Nasion, intersection of internasal suture with nasofrontal suture in midsagittal plane
- S - Sella turcica, midpoint of sella turcica
- Ar - Articulare, point of intersection of dorsal contours of mandibular process and temporal bone
- ANS - Anterior nasal spine, tip of ANS seen from norma lateralis
- PNS - Posterior nasal spine, tip of posterior spine of palatine bone in hard palate
- Point A - Deepest midline point on premaxilla between ANS and prosthion
- U1 - Upper 1, midpoint on incisor edge of most labially positioned maxillary central incisor
- B - Point B, most posterior point in concavity between infradentale and pogonion
- Mo - Molare, midpoint on occlusal contact between first molars
- Or - Orbitale, lowest point on lower margin of bony orbit
- Pr - Porion, midpoint on upper edge of porus acusticus externus
- Co - Condylion, most superior point on the head of condyle
- Go - Gonion, constructed point at the junction of ramal plane and mandibular plane
- Pog - Pogonion, most anterior point of bony chin in the median plane
- Gn - Gnathion, most anteroinferior point on the bony chin in the median plane
- Me - Menton, most inferior point on the bony chin in the median plane
- Sh - Point Sh, most highest point on the peripheral borders of the frontal sinus
- Sl - Point Sl, most lowest point on the peripheral borders of the frontal sinus
- An - Point An, most anterior point of maxillary sinus
- An' - Point An', point projected vertically from An to the x-axis
- Po - Point Po, most posterior point of maxillary sinus
- Po' - Point Po', point projected vertically from Po to the x-axis
- Su - Point Su, most superior point of maxillary sinus
- Su' - Point Su', point projected vertically from Su to the y-axis
- In - Point In, most inferior point of maxillary sinus
- In' - Point In', point projected vertically from into the y-axis.
Method of measurement
- SNA angle
- SNB angle
- ANB angle
- Saddle angle
- Gonial angle
- Facial angle
- Wits appraisal
- Total length of mandible (TML)
- Length of mandibular body (MBL).
The area measurement of maxillary sinus as shown in [Figure 4] were measured using the following method: 
The frontal sinus was traced by following the areas of high radiopacity as the peripheral areas.  The peripheral border of the frontal sinus was traced, and the highest (Sh) and lowest (Sl) points of its extensions were marked. Perpendicular to the interconnecting line Sh-Sl, the maximal width of the frontal sinus was assessed as shown in [Figure 5]. The results of all these variables were analyzed with Pearson correlation coefficient after descriptive statistics of all the variables.
- Maxillary sinus length: This line extends from An to the Po
- Maxillary sinus height: This line extends from Su to the In
- Upper maxillary sinus area (UMSA): Which defined by the area above maxillary plane that constructed from ANS to PNS
- Lower MSA (LMSA): This represents lower area of maxillary sinus from the palatal plane
- Total MSA: This represents summation of UMSA and LMSA.
Error of method
Lateral cephalograms tracings were evaluated twice by the same examiner with an interval of 1-week difference. Assessment of inter examiner reliability analysis was performed using kappa statistic. The inter examiner reliability was found to be kappa = 0.80-1.00 (P < 0.001) which shows perfect agreement according to Landis and Koch (1977).
| Results|| |
The descriptive statistics given in [Table 1] and [Table 2] and the Pearson's correlation coefficient given in [Table 3]. Pearson's correlation coefficient was calculated between frontal sinus and maxillary sinus with other variables in skeletal Class I, II, and III between males and females. In present study, on comparison of frontal sinus area (FSA) and MSA in skeletal classes shows skeletal Class III patients have more FSA compared to other skeletal classes and MSA shows large MSA in skeletal Class II patients as compared to other classes. Pearson's correlation coefficient shows significant correlation of frontal sinus with MBL and total mandibular length in skeletal Class III malocclusion patients in both males and females but maxillary sinus shows no significant relation with any variable used in the study.
|Table 1: The mean and SD of different variables in males in skeletal malocclusions I, II, and III |
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|Table 2: The mean and SD of different variables in females in skeletal malocclusions I, II, and III |
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|Table 3: Pearson's correlation test of different variables between males and females in skeletal malocclusion classes I, II, and III |
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| Discussion|| |
Lateral cephalograms have been most commonly used for diagnosis and evaluation of treatment outcome and are routinely used for orthodontic records. Malocclusion has been interpreted to be unfavorable deviations from the norms, and their morphologic characteristics have been studied extensively by analysis of the lateral cephalograms. The most relevant interesting characteristic of the present study was that the paranasal sinuses are compared for their role in assessing malocclusion skeletally. The bony chambers embedded into the bones around the nasal cavity and opening into the nasal cavity are called "paranasal sinuses." Of these, the maxillary sinuses are the largest of the paranasal sinuses.  The floor of the maxillary sinuses is formed by the alveolar process of the maxilla, ,, and its contiguity with the upper posterior teeth continues throughout life.  It could be hypothesized that the development of the maxillary sinuses, which have a close relationship with the maxilla structure and with the upper posterior teeth, might be affected by dental and skeletal malocclusions.  The frontal sinus is part of the paranasal sinuses that originates from the anterior ethmoidal cells that start their migration into the frontal bone at the end of the first year of life.  Despite the fact that several reports on the development of the frontal sinus are found, there are few studies that have investigated the relationship of frontal sinus with other skeletal parameters present in lateral cephalogram. Endo et al. found that maxillary sinus measurements show no significant difference between different skeletal classes in each gender.  Emirzeoglu et al. showed a significant difference in the volume of maxillary sinus between male and female, mainly due to the fact the male exhibit higher and wider maxillary sinus than female.  Oktay found that malocclusion and sex factor had no effect on maxillary sinus size and that sex was a significant factor only in angle Class II malocclusion.  Joffe found frontal sinus enlargement to be associated with prognathic subjects.  In a similar study reported by Rossouw et al. (1991) they had only compared the area of the frontal sinus in between adult skeletal Class III and adult skeletal Class I growth pattern cases but did not study the Class II growth pattern cases.  No study has been done in different types of skeletal malocclusions to evaluate the reliability of paranasal sinuses for depicting the skeletal pattern. Hence, the present study was done to evaluate the reliability of frontal sinus with that of maxillary sinus in assessment of different types of skeletal malocclusions and other skeletal features such as wits, facial angle, Gonial angle, Saddle angle, total mandibular length, and MBL.
In the present study, MSA was more in skeletal Class II malocclusion as compared to skeletal Class I and Class III malocclusion in males and females. This is in accordance with the study conducted by Dibbets  and Hopkin et al.  reported that the cranial base dimensions tend to be larger in male than female and larger in patients with Class II malocclusion than in those with Class I or Class III malocclusion. Patients with larger cranial bases tend to have larger maxillary sinuses; therefore, he suggests male Class II malocclusion has the largest mean value. It was found that though MSA is more in skeletal Class II malocclusion patients but it does not significantly correlate with any other variable used in the study to assess skeletal malocclusion as shown in [Table 3] (P > 0.05) and elaborated by Graph 1 and Graph 2. This is in accordance with the study conducted by Sassouni that maxillary sinus do not have a bearing on facial balance and malocclusions.  The results of our study are in the favor of study conducted by Jonas and Mann who reported that there was no correlation between facial and coexisting maxillary sinus asymmetries.  This point to some extent the findings of those of Okay, who investigated similar findings in orthopantogram.  The results of our study are also in favor of study conducted by Barghouth et al. and Sánchez Fernández et al. who reported that there are no statistically significant differences in maxillary sinus size between the sexes. , Endo et al. also found that maxillary sinus measurements show no significant difference between different skeletal classes in each gender. 
In the present study, FSA was found to be larger in skeletal Class III malocclusion. Skeletal Class III and Class II malocclusion are the extreme variations of the facial developmental process, depicting excessive and deficient mandibular growth respectively, so it was logical to look for a significant difference between the two malocclusions, which was shown by the present study. Though the FSA increased with mandibular prognathism as in skeletal Class III cases, It was not found to decrease in skeletal Class II malocclusion as compared to skeletal Class I malocclusion.  The findings of the present study were also in agreement with those of Rossouw et al. (1991). They demonstrated that a larger FSA was associated with excessive mandibular growth, as in case of skeletal Class III malocclusion. 
In our study, the FSA shows the significant correlation with SNA, SNB and with the Saddle angle in skeletal Class II malocclusion in both males and females as shown in [Table 3] and Graphs 3 and 4. The reason may be due to the increase in the thickness of the Nasion that was accounted for the enlargement of the frontal sinus.  Baer and Harris interpreted the development of the frontal sinus as process of structural adaptation to the forward and downward growth of the midface with the forward growth of the external lamina of frontal bone being essential to keep the contact with nasal bone and the maxilla.  In our study, the FSA shows no significant correlation with Gonial angle in skeletal malocclusions in both males and females as shown in [Table 3]. This is supported by Prashar et al. findings who found poor correlation of frontal sinus with Gonial angle which concluded that large frontal sinus may be present with large mandible irrespective of its growth direction, or the form of the mandible, with reference to its relation with body and ramus.  In our study, FSA shows a positive correlation with the total mandibular length in skeletal Class I and Class III malocclusion in both males and females as shown in [Table 3] and elaborated in Graph 3 and Graph 4. This is in accordance with study conducted by Guyer et al. (1986) who reported larger mandibular length in skeletal Class III sample as compared to skeletal Class I sample.  The results of present study suggested association between large mandible and FSA. Though maxillary sinus do not show significant relation some variables shows positive correlation with the maxillary sinus which is also intimated by the conclusion of the Koppe et al., who stated that external facial skeletal measurements are positively correlated by the maxillary sinus volume.  Though both males and females have been evaluated and have shown significant correlation with different variables of frontal sinus maxillary sinus does not show statistically significant difference in different types of skeletal malocclusions as shown in [Table 3]. Males shows more statistically significant result with different variables such as SNA, SNB, Saddle and facial and TML in skeletal Class II used in the study as compared to females which shows significant difference MBL and TML in skeletal Class III as shown in [Table 3]. This is supported by the study of Al-Sheakli et al. who found a significant difference in female's mandibular length as compared to males.  Although the use of two-dimensional lateral cephalogram along with small sample size may be the limiting factor, it is statistically demonstrated in this study that between the two paranasal sinuses, that is maxillary sinus and frontal sinus seen on lateral cephalogram frontal sinus, is a valuable indicator for assessment of skeletal malocclusion. Further research would be required to minimize the limiting factor by doing study on large sample size and using three-dimensional techniques for a better diagnosis and treatment planning.
| Conclusion|| |
- Though both paranasal sinuses clinically significant from anatomic viewpoint but from orthodontic point of view frontal sinus is more reliable as compared to maxillary sinus for the assessment of skeletal malocclusion
- FSA seems to be larger in case of skeletal Class III malocclusion as compared to skeletal Class I and skeletal Class II malocclusion and large frontal sinus associated with large mandible irrespective of its growth direction, or the form of the mandible
- There is no significant variation in MSA in males and females whereas frontal sinus shows significant variations in both males and females in different skeletal malocclusions.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]