Effects of Enlarged Adenoids on Craniofacial Growth in Bangalore Population – A Cross-Sectional Cephalometric Study

Introduction

The adenoid is a combination of lymphatic tissue in the posterior nasopharyngeal airway. Reduction of the posterior airway, be it by genetic factors or repeated adenoidal infection and inflammation, has been a suggested cause of altered craniofacial development and have been associated with the “adenoid face”.¹ Enlarged adenoids affects the lack of openness of the upper respiratory tract, and have been implicated for their ill effects on dentofacial development.²

Due to the enlarged adenoids, nasal breathing becomes difficult and the patients have a tendency for oral breathing.³ Mouth breathing habit requires numerous muscular changes; the lips repose, and tongue moves downward and forward, away from soft palate, thus changing the position of the mandible.^4,5,6 Due to the lowered tongue position, there is reduced muscular influence on lingual surface of maxillary teeth and absence of counteracting pressure on the lingual side to the buccal musculature, which results in the narrow maxillary arch.³

The presence of abnormally large adenoids in the pharyngeal space is said to be in conjunction with some abnormal features such as the increased face height, large angles between the mandibular line and the occlusal, nasal, and nasion-sella lines, lowered tongue position, and retroclined incisors in relation to their base lines,⁷ narrow alar bases, lip incompetence and a narrow or V-shaped maxillary arch.⁸

Recognizing an obstructed posterior airway is not always a simple task because its location normally prevents direct observation. Many aids have been used for diagnosis, including nasal resistance and airflow tests, nasoendoscopy, lateral cephalometry, and threedimensional imaging; each possesses positive and negative qualities. However, there is no agreement on the gold standard procedure for diagnosing posterior airway obstruction. The lateral cephalogram is a commonly used sagittal X-ray of the head and neck. It is perhaps the most commonly used of the tests, especially by dentists. It is an easy, less expensive, readily available, and duplicable way to diagnose upper airway obstruction. Many studies have advocated the use of lateral cephalograms, and several adenoid and nasopharyngeal measurements have been proposed.

The main aim of this study was to determine the effects of enlarged adenoids on the growth pattern of maxilla and mandible. The effects of enlarged adenoids on the dentition and the relationship between airway size and lip strain were evaluated.

Null hypothesis: No relationship exists between the enlarged adenoids, airway size, dentition and lip strain.

Research hypothesis: A relationship exists between the enlarged adenoids, airway size, dentition and lip strain.

Materials and Method

The present study considered purposive sampling of twenty-five children having enlarged adenoids with sizes ranging from 5-1 mm, and were selected based on the following criteria:

1. All subjects had to be Indian nationals, their age ranging between 5 years to 14 years with enlarged adenoids and a history of repeated infection.

2. Subjects without history of previous orthodontic treatment

3. Lateral cephalograms with readily identifiable landmarks

Method

This cross-sectional study was carried out at the Department of ENT and Paediatrics at Manipal Hospital, Bangalore. A total of twenty-five children from the outpatient department, who satisfied the inclusion criteria were selected for the study. Pre-treatment lateral cephalograms were traced to measure the width of airway, size and position of maxilla and mandible and its correlation to the enlarged adenoids and/or tonsils.

Inclusion Criteria

1. Children with enlarged adenoids and/or tonsils with a history of repeated infection

2. No history of previous orthodontic treatment

3. Lateral cephalograms with readily identifiable landmarks

Exclusion Criteria

1. Children with acute adenoid and/or tonsil infection

Pre-treatment lateral cephalograms were taken with Siemens cephalogram model no. CT5-CTE-10967 using Fujifilm film. Lateral cephalograms were recorded with the subject in a standing position, keeping the visual axis parallel to the floor. A standard radiographic exposure comprising of usual parameters viz. 58 – 62 kvp, 8-12 ma and an exposure time automatically selected was used. The distance between the x-ray source and the patient’s mid-sagittal plane was 155 centimeters and that from the mid-sagittal plane to the x-ray film cassette was 15 centimeters.

The important variables considered in the present study in relevance to the objective stated were upper lip strain, upper pharynx size. Upper lip strain is the difference between the upper lip thickness and the basic upper lip thickness, while the upper pharynx size was measured from a point on the posterior outline of the soft palate to the closest point on the pharyngeal wall.

All the tracings were made on 75µm lacquered polyester acetate tracing papers using a 0.05” Stadler lead pencil. A single operator performed all the tracings in a standardized manner to avoid errors due to any inter-operator variations. Later, ten radiographs were selected randomly, retraced and re-measured to assess intra-operator reliability and easy to replicate of various parameters.

Statistical Analysis

The following methods of statistical analysis have been used in this study. Data was entered in Microsoft excel and analyzed using SPSS (Statistical Package for Social Science, Ver.10.0.5) package.

Mean and standard deviations were computed for each independent variable (Table 2), as well as Pearson product moment correlation coefficients, to assess multicollinearity. Individual regression analyses were performed with gender, age, upper lip strain, upper pharynx size as the independent variables and the cephalometric measures as the dependent variables. The level of significance was set at ≤0.05.

Hard Tissue Landmarks (Figure 1)

1. Sella (S): Geometric centre of the pituitary fossa. It is a constructed (radiological) point in the median plane.

2. Nasion (N): Anterior most point on the nasofrontal suture in the median plane.

3. Orbitale (Or): Bottom most point of the orbit in the radiograph.

4. Porion (Po): The highest point on the superior surface of external auditory meatus.

5. Anterior nasal spine (ANS): The anterior tip of anterior nasal spine.

6. Posterior nasal spine (PNS): Point in continuation of the anterior wall of pterygopalatine fossa and the floor of the nasal fossa.

7. Subspinale (A): Posterior most midline point between the ANS and the prosthion (the most inferior point on the alveolar bone overlying the maxillary incisors).

8. Supramentale (B): Posterior most point in the concavity of the mandible between the infradentale and the hard tissue pogonion.

9. Pogonion (Pog): Most anterior point of chin.

10. Gnathion (Gn): A point located between the most anterior and inferior point of the bony chin. 11. Menton (Me): Lower point in the outline of the symphysis.

12. Gonion (Go): A constructed point, the conjunction of the line’s tangent to the posterior margin of the ascending ramus and mandibular base.

13. Articulare (Ar): Point at the posterior margin of the ascending ramus and the outer margin of the posterior cranial base.

14. Condylion (Cd): Superior most point on the head of the condyle.

15. Pterygomaxillary fissure (Ptm): A bilateral teardrop– shaped radiolucency, which represents the posterior surfaces of the tuberosities of the maxilla.

16. Basion (Ba): The anterior margin of the foramen magnum, on the slope of the inferior border of the basilar part of the occipital bone to its posterior limit.

17. Sellae: Midpoint of the sella – this point represents the midpoint of connecting the posterior clinoid process and the anterior opening of the sella turcica; it is at the same level as the jugum sphenoidale and it is independent of the depth of the sella (Schwarz).

Soft tissue Landmarks (Figure 2)

1. Li – labrale inferius - the middle point in the inferior margin of the lower membranous lip.

2. Ls – labrale superius - the middle point in the superior margin of the upper membranous lip.

3. Up – mark on the pharynx side of the soft palate.

4. ppw – posterior side of the pharyngeal wall.

Results

The study included 15 boys and 10 girls. The mean age of the subjects was 10 years, with an age range of 5 to 13 years.

Table 1 shows the average values and ranges for the demographic and independent variables such as gender, age, upper-lip strain, upper pharynx and lower pharynx size. Gender breakdown of the sample was 60% girls, 40% boys. The normal upper pharynx size ranges between 15 to 20 mm and when the adenoids are enlarged, the width of the upper pharynx reduces. This study considered cases where the width of the upper pharynx ranged from 5 – 11mm.

Table 2 depicts the association between the independent variables and the various cephalometric dependent variables, together with the respective coefficients of explained variance (R-square) as determined by multiple regression analysis. The median of the explained variances was 0.279. For twelve of twentyfour variables, the explained variance was more than 0.30. The highest value (0.563) was noted for Jaraback ratio. Results of the analysis for lip posture and sagittal airway size were discussed. They were constructed by calculating the value of each dependent variable using the mean of values for each independent variable.

Table 3 shows the inference of the analysis for upper lip strain and upper pharynx size as discussed separately.

Upper-lip strain

Skeletal: Upper lip strain was associated with an increase in SNA angle and lower jaw plane angle.

Dental: There was no significance observed.

Upper-pharynx size

Skeletal: A reduction in the size of upper pharynx was associated with decrease in mandibular size (mandibular corpus size), increase in gonial angle (Ar-Go-Gn), decrease in middle third of face (N- ANS) and increase in lower anterior facial height (ANS- Me).

Dental: A reduction in the upper pharynx was associated with increase in the degree of mandibular incisor proclination relative to mandibular plane.

Discussion

The present study is unique in that it is the first attempt to separate the associations of craniofacial morphology among the parameters of upper lip strain and upper pharynx size. The inference of the present study demonstrates that the above-mentioned parameters were associated with coherent but different skeletal configurations and suggests facial skeletal adaptations to specific environmental stimuli.

Skeletal changes

The skeletal pattern associated with upper-lip strain (Table 2) appeared to be unrelated with upper pharynx size. An increased upper lip strain was associated with forward positioning of the upper jaw and anti-clockwise rotation of the mandible in comparison to the sellanasion line. Similar observations were made by Kalevi Koshi et al.⁵ that the angles between the mandibular lines and occlusal and nasion-sella lines were increased. Similar findings were observed even by Linder Aronson and McNamara JA.^4,10 The sella-nasion dimension varied proportionally such that the angle SNA and SNB were unaffected.

The skeletal changes associated with abnormal condition of reduction in upper pharynx size due to enlarged adenoids (Table 2) was characterized by backward rotation of lower jaw in relation to the cranial base, a shorter mandibular body size and decreased mid-face height. Behlfelt,¹¹ Handelman CS and Osborne G¹² also found similar findings of reduced mandibular arch length, larger mandibular plane angle and increase in the lower facial height.

Skeletal pattern in conjunction with reduced upper pharynx size due to enlarged adenoids (Table 2) was characterized by increased gonial angle.

A reduction in the upper pharynx size caused by an enlarged adenoid was characterized by increase in the lower anterior facial height¹³ (Table 2). This was in accordance with the study conducted by Trottman et al⁷ in which an elongated total facial height, mainly the lower anterior facial height was observed in case of increased sagittal airway size.

Solow et al⁷ showed that in the cases of enlarged adenoids, an increased craniocervical angle was observed along with reduced linear lower jaw dimensions, mandible being retrognathic, and a large inclination of the mandible in conjunction to the anterior cranial base.

Dental Changes

Dental changes related to reduced upper pharynx size associated with enlarged adenoids were characterized by mandibular incisor proclination relative to mandibular plane.^14,15 There was a large difference in the angulation of the upper incisors to the palatal plane, which was noticed as the age progressed i.e., more upright in the younger age group compared to the older age group.

Soft tissue changes

The interaction of soft tissues was not significant with upper lip strain, upper pharynx size. The results of this study reinforce the findings reported by Trottman CA et al,⁷ who observed that in a more open lip posture, there was an anti-clockwise rotation of the maxilla and mandible, an increased gonial angle, a retruded mandible with retroclined incisors, extruded maxillary molars and upper and lower anteriors, and these were indicative of a backward rotating growth pattern. The skeletal pattern associated with reduction in sagittal airway size due to enlarged adenoids was characterized by an enbloc backward rotation of the upper and lower jaws (including the dental arches) in conjunction to the cranial base and by a shorter mandibular body.

There were a few drawbacks which were observed in this present study. The cephalograms are the two-dimensional representation of three-dimensional object; hence exact representation of landmarks was not possible. Perhaps the most important limitation of cephalometry relates to the errors inherent with the identification and recording of the structures therein. Also, cephalograms were traced by a single operator and hence inter-operator variability was not studied. A larger sample size would have been desirable to increase statistical power.

Conclusion

1. The skeletal changes associated with increased upper lip strain and reduced upper pharynx width were forward maxillary placement, retrognathic mandible, anti-clockwise rotation of the mandible, decreased middle third of face and increase in lower anterior face height.

2. With the reduction in the upper pharynx width, there was an increase in the degree of mandibular incisor proclination relative to mandibular plane.

3. No significant soft tissue changes were observed.

Conflict of Interest

None.