A soft liner is an elastic or viscoelastic material placed on the tissue surface of a denture or obturator to cushion and evenly distribute chewing forces, acting like the periodontal ligament or healthy oral mucosa [1,2]. Resilient lining materials have been used in complete dentures since their first clinical use by Tylman. They help relieve persistent denture discomfort caused by thin mucosa, irregular bone, or low pain tolerance, especially under lower dentures where chewing pressure is greater [3,4]. Resilient lining materials are mainly used for patients who cannot tolerate excessive denture pressures. They act as shock absorbers, cushioning the underlying tissues and reducing the transmission of masticatory forces to the denture-bearing basal seat [5-7].

An obturator is a prosthesis used to close and rehabilitate congenital and/or acquired maxillary defects. It reestablishes a barrier between the oral and nasal cavities, restores normal oral function, improves speech, swallowing and mastication, enhances esthetics, and provides better patient comfort and quality of life [8-11].

Severe resorption of the mandibular ridge contributes to instability and discomfort associated with conventional acrylic resin dentures [12]. In such cases, the use of a resilient liner improves denture adaptation by cushioning the underlying tissues, distributing occlusal forces more evenly, enhancing retention and stability, reducing pain during function, and making the denture more comfortable and functional for the patient [13]. Soft lining materials absorb and distribute masticatory forces, reducing direct stress on atrophied ridges. They provide more uniform pressure over the residual ridge, minimize trauma to prominent bony spicules, and improve denture comfort and function [14,15].

Soft liners allow abused or traumatized oral tissues to adapt and recover under functional loading, promoting a more even distribution of masticatory forces across the entire denture-bearing area. As a result, the oral mucosa beneath the removable denture is less likely to be traumatized, reducing tissue irritation, improving comfort, and enhancing denture function [16-20].

There is limited evidence in Bangladesh on the effects of soft lining materials in denture and obturator patients, particularly regarding comfort, chewing efficiency, and phonation. Their clinical use is still not well established, and no local comparative studies have assessed these outcomes. Therefore, this study aims to evaluate and compare the effect of soft lining materials on comfort, chewing efficiency, and phonation in denture and obturator wearers in Bangladesh.

This prospective longitudinal study was conducted in the Department of Prosthodontics, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh, from January 2008 to December 2010. A total of 60 patients were included and divided into two groups: 30 received soft-lined dentures and obturators (Group A) and 30 received conventional prostheses without soft lining (Group B). Patients were selected through detailed history, clinical examination, diagnostic analysis, and radiographic evaluation. After informed consent and standard aseptic fabrication procedures, the prostheses were fabricated, finished, polished, and inserted. In Group A (soft-lined dentures and obturators), additional procedures were performed after insertion. The denture was seated using centric occlusion and intercuspation to ensure proper adaptation. Borders were reduced by 1–2 mm (except the posterior maxillary border) and refined using low-fusing compound. A closed-mouth impression was then taken with zinc oxide-eugenol paste in intercuspal position, and the impression was poured in hard plaster. The cast was invested in a flask, and after setting, the impression material was removed using warm water. The tissue surface of the denture/obturator was reduced by 1–3 mm using a grinding stone, and undercuts were prepared for mechanical retention. A separating medium was applied to the plaster and a bonding agent to the resin surface. Molloplast-B soft liner was then adapted onto the base, packed using the conventional method, and flask closure was achieved with metal-to-metal contact before curing according to the manufacturer’s instructions. After curing and bench cooling, the prosthesis was deflasked, cleaned ultrasonically, and excess material was trimmed and contoured. Final finishing and polishing were performed, and the soft-lined denture/obturator was inserted with proper patient instructions. After insertion, baseline comfort, chewing efficiency, and phonation were assessed in both groups and recorded. Patients were followed up at 1, 3, and 5 weeks and at 5 months, with the same parameters evaluated at each visit and data documented for analysis.

Table I shows the distribution of patient’s comfort with denture and obturator for a period of 5 months. However, during different study period, comfort was improved significantly (p<0.05) in group-A patients compared to group-B patients.

Table I: Distribution of patients by comfort during different study periods (n=60)

Chi-square test is done to determine the p value

Group-A (n=30): Patients treated with soft lining material

Group-B (n=30): Patients treated without soft lining material

Table II represents the distribution of chewing efficiency. The baseline data indicated that no statistically significant difference was found between two groups of patients (p>0.05). After treatment the chewing efficiency increased more in patients treated with soft lining materials in group A than patients treated without soft lining materials in group B and the difference was highly statistically significant (p<0.05).

Table II: Distribution of patients by chewing efficiency during different study period (n=60)

Chi-square test is done to determine the p value

Group-A (n=30): Patients treated with soft lining material

Group-B (n=30): Patients treated without soft lining material

Table III shows status of phonation of patients wearing prosthesis with and without soft lining materials. Initially no statistically significant difference was found between two groups of patients in terms of phonation (p>0.05). On 1st and 3rd week study period, statistically significant improvement of phonation was observed in group-A patients (p<0.05). On 5th week and at the end of 5 months study period, the improvement was a little bit lower in group-A patients and difference was not statistically significant (p>0.05).

Table III: Distribution of patients by phonation during different study period (n=60)

Chi-square test is done to determine the p value

Group-A (n=30): Patients treated with soft lining material

Group-B (n=30): Patients treated without soft lining material

This study was conducted to compare the comfort, chewing efficacy and phonation of patients wearing denture/obturator with and without soft lining materials. The results of the present study reveal that comfort, chewing efficacy and phonation increased more in patients treated with soft lining materials (group A) than patients treated without soft lining materials (group-B).

In this present study, soft-lined denture and obturator wearer felt comfort more (86.7%) compared to the patients without soft-lined prostheses (53.3%). Similarly, phonation and chewing efficacy increased 80% in patients wearing denture and obturator with soft lining materials compared with those patients (60%) without soft lining materials.

Previously conducted some similar studies showed that the dentures lined by Molloplast-B was comfortable in 93% patients [21,22]. In these studies dentures and obturators were lined with Molloplast-B, a silicone based soft lining material and chewing or masticatory function improved in 80% of patients.

So, the present study is more or less consistent in terms comfort and chewing efficacy with the studies conducted previously [21,22].

Another study proved that the use of long-term soft linings improves speech of patients wearing complete dentures with soft liners compared to patients wearing complete dentures without using soft liners [23]. The result of this study in terms of phonation is also consistent with the result of the present study.

Soft lining materials significantly improved denture and obturator patients’ comfort and chewing efficiency compared to conventional prostheses, showing consistent and statistically significant benefits over the follow-up period. Although phonation improved in the early stages, long-term differences between the two groups were not statistically significant. Overall, soft liners were found to be more effective in enhancing functional outcomes, particularly comfort and mastication, in denture and obturator wearers.

ACKNOWLEDGEMENT

We gratefully acknowledge all the patients and their attendances participated in this study. We would also like to acknowledge the Department of Prosthodontics, BSMMU where the study was carried out.

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