Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2015  |  Volume : 26  |  Issue : 2  |  Page : 144--147

Dimensional change in soft tissues with complete dental prosthesis and its effect on airway space and natural head position


TV Padmanabhan1, R Fathima Banu1, A Mahalakshmi2, Abdul Aziz3, Suman Bohra3, V Anand Kumar1,  
1 Department of Prosthodontics, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India
2 Ponniyah Ramajayam Institute Of Medical Science, Dr. M.G.R Medical University, Nallur, Chennai, Tamil Nadu, India
3 Clinician, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. R Fathima Banu
Department of Prosthodontics, Sri Ramachandra University, Porur, Chennai, Tamil Nadu
India

Abstract

Background: Insertion of the intraoral prosthesis causes deflection of the tongue, soft palate affecting the patency of the airway. Aims: To evaluate the cephalometric soft tissue variation in tongue, soft palate, and its effect on posterior airway space in edentulous patients with the insertion of the denture. Settings and Design: Randomized controlled trial. Materials and Methods: Complete denture (CD) prosthesis was fabricated for first time denture wearers comprising 22 males and 18 females within the age range of 50-65 years. Lateral skull radiographs were taken for each of the subjects in their resting position without CDs (T0), with CDs (T1) at least 1-week postinsertion and after 6 months of usage (T2), respectively. The reference points, lines, and angles on the cephalometric films were used to evaluate the position or inclination of the head, variations in tongue position and length, the changes in the anteroposterior dimension of the soft palate, and posterior airway space variations. Intra-investigator error variance was not found to be statistically significant (P < 0.05). Statistical Analysis Used: Using Statistical Package for the Social Sciences (SPSS) v16.0 the significant difference in the paired samples (without CD and with CD) was found using the paired t-test. The probability value P = 0.05 is considered as a significant level. Results : On comparison of T1 and T0, the heads were more extended with the downward position of the tongue with an increase in its length and the posterior airway space was decreased in T1. Significant differences in values were not observed between T1 and T2. Conclusions : With CDs, the change in airway space was related to alteration in soft palate and tongue dimension. There were no changes in dimension at 6 months follow-up.



How to cite this article:
Padmanabhan T V, Banu R F, Mahalakshmi A, Aziz A, Bohra S, Kumar V A. Dimensional change in soft tissues with complete dental prosthesis and its effect on airway space and natural head position.Indian J Dent Res 2015;26:144-147


How to cite this URL:
Padmanabhan T V, Banu R F, Mahalakshmi A, Aziz A, Bohra S, Kumar V A. Dimensional change in soft tissues with complete dental prosthesis and its effect on airway space and natural head position. Indian J Dent Res [serial online] 2015 [cited 2022 Jan 25 ];26:144-147
Available from: https://www.ijdr.in/text.asp?2015/26/2/144/159140


Full Text

Edentulism affects lower facial height due to loss of vertical dimension. Loss of vertical dimension is a gradual and continuous process in an edentulous patient with altered phonetic and masticatory functions leading to muscular discomfort and accelerated residual ridge resorption. [1] These often results in pharyngeal musculature alteration associated with obstructive sleep apnea. [2] To regain lost function and aesthetic, the complete dental prosthesis was considered to be the prime mode of rehabilitation.

Association between the complete dental prosthesis and soft tissues has been an issue of concern for the past decade due to increasing geriatric population. Literature states that insertion of the intraoral prosthesis causes deflection of the tongue, [3] affecting the patency of the airway. [4] The pharyngeal airway is the principal mechanism in controlling the natural head posture (NHP) which was found to be constant for each individual [5] and it was found to be extended with insertion of prosthesis by Cleall. [3] The relationship between cervical and orofacial region were previously studied using cephalometric analysis, and various cephalometric variables indicated the morphological changes of the face and postural changes of the head. [6],[7] To assess the craniofacial morphology, NHP was considered a more stable landmark in comparison to the intracranial reference lines.

Although the association between NHP and airway space are well explained, no evaluation of correlation between soft tissues such as tongue and soft palate with complete denture (CD) on posterior airway space have been done so far. It may be considered that posterior rotation of mandible would result in movement of the hyoid, and it encroach the airway space leading to a compensatory change in NHP which may be reversible by the rehabilitation of edentulism. Hence, to evaluate this hypothesis, the present study aims to evaluate in edentulous patients with and without CD in relation to the following features:

The cephalometric variation in tongue, soft palateInfluence of soft tissue changes of the posterior airway spaceTo confirm the change in posterior airway space using natural head position.

 Materials and Methods



An Institutional Ethical Committee clearance reference No. Csp/11/Aug/18/59 was obtained for carrying out the study with 40 completely edentulous patients. The study consisted of 22 men and 18 women within the age range of 50-65 years and the mean age of 58 years. The participants presented to the Department of Prosthodontics, Faculty of Dentistry, Sri Ramachandra University for CD treatment with no previous history of CD rehabilitation. Subjects with a history of temporomandibular disorders, sleep disorders, or head/neck injury and with skeletal deformity were excluded. All of the subjects had a history of uneventful tooth extraction, not <6 months.

All preliminary impressions were made using modeling compound, which were beaded and boxed for the fabrication of diagnostic model with plaster of paris (MAARC, Shiva Products, Maharashtra, India). Custom trays for selective pressure technique were designed with a full spacer and fabricated using autopolymerizing resin (DPI-self cure resin). Border molding was done with low fusing impression compound (DPI-Pinnacle impression tracing sticks) and final impressions were made with medium body polyvinyl siloxane impression material (Aquasil, Densply products) and master cast were poured using dental stone gypsum material (MAARC, Shiva Products, Maharashtra, India).

Denture bases were fabricated with 2 mm thickness using autopolymerizing resin. The thickness was verified with metal gauge. The occlusal rims were made of base plate waxes (MAARC, Shiva Products, Maharashtra, India). Appropriate vertical dimension was assessed, [10] and the maxillary rims were oriented the hanau wide-vue articulator using hanau spring bow. Centric relation was determined using intraoral tracing method. [8] Bilateral balanced occlusion CD trial prosthesis using semi anatomic teeth was fabricated and evaluated at all clinical stages by a single clinician. The processed dentures were confirmed to be of good quality according to evaluation scores for CDs after placement. [9]

Using a cephalometric unit (Planmeca-PM 200), lateral cephalogram images were taken for each subject in their resting position at three stages such as without CDs (T0), with CDs (T1) at least 1-week postinsertion, and after 6 months of usage (T2), respectively. A calibration of the radiographic technique was also performed, and radiographs were taken with a film-to-focus distance of 180 cm and a film-to-median plane distance of 10 cm. Subjects were asked to look into a mirror at eye level on the opposite wall (mirror position) in order to record the natural head position. [12],[14] Based on the outer border of the radiograph, vertical (Ver) and horizontal lines (Hor) were traced perpendicular to each other. These two lines were the references to calculate the angles between the head and neck on the cephalograms.

The reference points, lines, and angles on the cephalometric films were used to (1) Evaluate the position or inclination of the head (craniovertical inclination [sella-nasion line (SN)]/vertical line (Ver) and NL/Ver), cervicohorizontal inclination (OPT/Hor and CVT/Hor) [11] (2) analyze variations in tongue position and length (V-T), (VT/FH) (V┴ FH) [11] (3) analyze the changes in the anteroposterior dimension of the soft palate (pm-U) (4) evaluate posterior airway space variations-the upper airway space (pm-UPW); middle airway space (U-MPW); inferior airway space (V-LPW) [13] which are illustrated in [Figure 1]. The assessment was done as follows.{Figure 1}

Head inclination

Craniovertical inclination is assessed by measuring the angle between the (SN/Ver)Tongue length and position assessmentDistance between the vallecula and the tip of tongue (V-T)Perpendicular distance between vallecula and Frankfort horizontal plane (V ┴ FH)The angle between the plane connecting vallecula and tip of the tongue with the V ┴ FH.Anteroposterior dimension assessment of soft palateThe distance between tip of the uvula pterygomaxillary and tip of the uvula (pm-U).Posterior airway space assessmentUpper airway space - Distance between the pterygomaxillary and upper pharyngeal wall (pm-UPW)Middle airway space - Distance between the tip of the uvula and middle pharyngeal wall (U-MPW)Lower airway space - Distance between the vallecula and the lower pharyngeal wall (V-LPW).

To assess errors, which may be due to landmark identification, duplicate measurements were made on all radiographs by the same investigator. Intra-investigator reliability was evaluated using an independent sample t-test to determine whether any significant difference existed between the first and second measurements for all parameters. Intra-investigator error variance was not found to be statistically significant (P < 0.05).

The collected data were analyzed with Statistical Package for the Social Sciences (SPSS) 16.0 version. To describe about the data, mean and standard deviation were used. To find the significance difference in the paired samples (without CD and after CD) paired t-test was used.

 RESULTS



At T0 and T1, there was a significant decrease in OPT/Hor (0.49°) (P < 0.001) and CVT/Hor (0.79°) while there was increase in SN/Ver (-0.863°) and NL/Ver (-0.45°) angles (P < 0.001) compared to T0. These results depict an extended head with the insertion of CD in relation to the floor [Table 1] and [Table 2].{Table 1}{Table 2}

On assessing the tongue dimension, a variance in length of the tongue was also observed with the presence of CD. A statistical significant increase in perpendicular distance from vallecula to V ┴ FH (0.812 mm), tongue length (1.7 mm), and a decrease of 4.1° between the horizontal axis of tongue with the V ┴ FH was seen. It shows a downward position of the tongue along with an increase in its length [Table 1] and [Table 2].

With the CDs, the measurements of the soft palate illustrate a significant increase in its length (0.428 mm). The angulation of soft palate in relation to the palatal plane showed an increase (0.6°) but not statistically significant [Table 1] and [Table 2].

On observing the changes in relation to the posterior airway space, the CDs caused an overall reduction in entire airway space. A statically significant decrease of 0.6 mm in superior airway space, 0.7 mm in U-MPW, and 1.15 mm at V-LPW were found [Table 1] and [Table 2].

On comparison of the results, significant differences in values were not observed between T1 and T2. Since the difference between them was zero, statistical analysis could not be performed.

 DISCUSSION



The present study has shown that with complete dental prosthesis there is encroachment of the airway space. The superior, middle, and V-LPWs were reduced in its dimension due to increase in tongue length and changes in dimensions of the soft palate in the presence of CD.

On analyzing the natural head position, it was observed that there was an increase in cranio vertical angle indicating an extension of the head, which was due to increase in airway diameter. [15],[16] The observed extension of the head is a physiological compensatory mechanism to aid oral breathing. [13],[17] Though the compensatory mechanism indicates that airway space has reduced in dimension, the rationale behind the mechanism was not analyzed previously. Hence, to analyze the anatomical variation caused by CD, which would have influenced on airway dimensions, the anatomy of soft palate and tongue was evaluated.

On evaluating the soft palate, the significant morphological change was observed with increase in the soft palate of 0.428 mm in CD wearers. Moreover, the positional relation of the soft palate with palatal plane also increased by 0.6°, though it was not statistically significant. The change in soft palate length and position could be due to physiologic recording of posterior palatal seal area with CD, which would have caused the soft palate to rise from its position. Hence, with effect from the soft palate, closure of superior and U-MPW with complete dental prosthesis were observed.

Another significant finding observed was an increase in tongue length by 1.7 mm, in addition there was downward and posterior shift of vallecula which was evident from 4.1° decrease in angle formed by horizontal axis of tongue with FH plane and the increase in distance of vallecula from the FH plane by 0.812 mm. The increase in tongue length was due to the encroachment of the tongue space with lingual flange and palatal plate. [5] Since the tongue space available in the complete edentulous state (collapsed vertical dimension condition) were more due to posterior rotation of the mandible and pseudo class III relationship. [18]

On assessing the airway space, the decreased dimension in the present study was related to CD with its effect on soft palate and tongue. The present study was followed up at 6 months to assess the long-term changes, which showed no change in the soft tissues and airway space dimension. Hence, it could be suggested that the patient with prolonged edentulism would have a significant effect on the tongue and soft palate, and consequently CD has an indirect effect on airway space. The results from the present study confirm the hypothesis of effect on the tongue and soft palate on posterior airway dimensions.

 CONCLUSIONS



The present study concluded that the change in airway space was related to alteration in the soft palate and tongue dimension with effect from CD insertion. The present study also showed no change in the soft tissues and airway space dimension at 6 months follow-up suggesting that the patient with CD would have significant effect on tongue and soft palate and consequently has an indirect effect on airway space. Hence, rehabilitation with fixed or hybrid prosthesis should be considered as a better option for the geriatric patient.

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