A lisp (sigmatism) is a common temporary speech distortion that occurs when adjusting to new or ill-fitting dentures. This change in speech clarity, particularly affecting the “S” and “Z” sounds, happens because the prosthetic alters the precise oral environment needed for clear articulation. While frustrating, this is a normal side effect of introducing a foreign object into the mouth. Understanding the cause and applying targeted solutions, from focused practice to professional adjustments, can effectively resolve this issue, allowing the wearer to regain clear speech.
Understanding the Mechanics of Denture-Related Lisping
The primary cause of denture-related lisping is the disruption of the tongue’s ability to create the narrow channel necessary for sibilant sounds like “S” and “Z”. These sounds are produced when the tongue directs a small stream of air through a groove formed against the palate or the front teeth. The denture base, particularly in the upper arch, introduces a new, often thicker, surface that changes the shape of the roof of the mouth.
The addition of acrylic material, especially if the denture base is thicker than the recommended 1.4 to 2 millimeters, reduces the available space for the tongue. This lack of space alters the tongue’s resting and speaking position, which can result in the air escaping too broadly, leading to a “swish” or “sh” sound. Conversely, if the space is too small, the air channel can become constricted, producing a high-pitched whistle.
The position of the prosthetic teeth also plays a role, as the relationship between the tongue, the palate, and the upper and lower incisors is specific for sound production.
Self-Correction Methods and Practice Routines
Most initial lisping is temporary and can be resolved through consistent practice, as the mouth and brain need time to adapt to the new appliance. One of the most effective techniques is reading aloud for several minutes each day, deliberately focusing on clear pronunciation and enunciation. This practice allows the mouth muscles to build new memory for speech patterns with the dentures in place.
Focus on sounds that are causing the distortion, which are typically the sibilant sounds like “S,” “Z,” “Sh,” and “Ch”. Practice repeating words and phrases that contain these sounds, such as tongue twisters like “She sells seashells”. While practicing, consciously slow down your rate of speech to allow your tongue to find the optimal placement for directing the airflow.
Using a mirror can be highly beneficial, as it allows you to observe your mouth movements and ensure your tongue is not protruding between your teeth, which is a common cause of a frontal lisp. Try biting down gently and smiling while attempting the “S” sound; this ensures the tongue is positioned behind the teeth and forces the air forward. Consistency is paramount, and incorporating short, frequent practice sessions throughout the day is more effective than one long session.
Identifying and Addressing Physical Fit Issues
If a lisp persists beyond the initial adjustment period—typically a few weeks—the cause may be a physical flaw in the denture’s design that requires professional intervention. A clear sign of a fit issue is if the denture moves or slips while you are speaking, which makes controlled articulation impossible. This lack of stability can be caused by an old denture no longer fitting the changing gum and bone contours, or an improper initial fit.
Structural issues relating to the prosthetic’s dimensions may also be the cause. Excessive thickness of the acrylic in the palate can permanently restrict the tongue’s movement and cause persistent speech difficulties. Furthermore, the position of the front teeth or the vertical dimension (the space between the upper and lower jaws when the mouth is closed) can be incorrect, throwing off the natural alignment needed for speech.
A dentist or prosthodontist can assess these structural problems by checking the closest speaking space using the “S” sound. Adjustments may involve minor filing, trimming the edges, or a reline to improve the fit to the gum tissue. If speech distortion continues even after the fit is corrected and practice has been consistent, a referral to a speech-language pathologist may be necessary to address deeply ingrained speech habits.