The Challenge of Pain Measurement in Oral Surgery
For patients undergoing oral and maxillofacial surgery (OMFS) – whether it’s a wisdom tooth extraction or a jaw reconstruction – pain is an almost inevitable part of recovery. Yet, how do we accurately measure that pain? As healthcare providers (and as developers of PainSense), we recognize that assessing pain isn’t as simple as asking “How much does it hurt?” Pain is a highly subjective, multifaceted experience[1]. Factors like individual pain thresholds, emotions, and even communication ability all influence how pain is perceived and reported[1]. No two patients interpret pain in exactly the same way, which makes standardized measurement a real challenge[2].
This challenge has very real implications. Effective pain management after surgery relies on accurate pain assessment[2]. If a patient’s pain is underestimated, they may suffer needlessly; if overestimated, they might receive unnecessary medication. In OMFS, where post-operative pain can be significant, having reliable pain metrics is essential for guiding treatment decisions and ensuring patient comfort. The assessment of pain intensity is a routine part of clinical practice – we always ask patients to rate their pain – but doing so in a simple, practical, and consistent way is easier said than done[3]. Over the years, many pain measurement tools have been developed specifically for dentistry and oral surgery[3], each with its own strengths and limitations. These tools range from quick one-dimensional rating scales to detailed multi-factor questionnaires.
In this article, we at PainSense will summarize key insights from a notable 2017 review on pain measurement in OMFS[4]. We’ll discuss the types of pain scales available – multidimensional vs. unidimensional scales – and their clinical applications, especially in post-operative pain management. We’ll also share how this knowledge aligns with our mission at PainSense, where we’re developing a device to make pain measurement more objective and reliable in oral surgery. Let’s delve into how pain is measured today and how we’re working to improve it.
Pain Measurement Scales in Oral and Maxillofacial Surgery
Accurately measuring pain in OMFS often involves using standardized pain scales. According to the literature, these scales generally fall into two categories: multidimensional and unidimensional[5]. The 2017 review by Sirintawat et al. highlighted that multidimensional scales (like the McGill Pain Questionnaire) are well-suited for chronic pain, whereas unidimensional scales (like the 0–10 rating scales or visual analog scales) are typically used for acute post-surgical pain[5]. Below, we break down what that means and which tools are commonly used in each category.
Add Your Heading Text Here
Multidimensional pain scales aim to capture a comprehensive picture of pain, beyond just intensity[6]. These tools assess various aspects of the pain experience – such as the pain’s quality, location, duration, and emotional impact – all of which can be important in complex or long-lasting pain conditions[6]. In oral and maxillofacial surgery, multidimensional scales are especially useful for chronic pain cases (for example, temporomandibular joint disorders or cancer-related oral pain) that affect a patient’s quality of life over time[6].
One classic example is the McGill Pain Questionnaire (MPQ), first developed in the 1970s. The MPQ presents patients with a list of descriptive words for pain (sensory, affective, evaluative, etc.) and asks them to choose which words match their pain[7]. This generates a pain profile and a score (the Pain Rating Index). The MPQ’s strength lies in its depth – it’s proven to be reliable and valid, capturing the “multidimensionality” of pain beyond just a number[7]. However, a major drawback is that it’s lengthy and complex: filling out the full MPQ can take up to 30 minutes, which is tedious for patients who are in pain[8]. For this reason, a Short-Form McGill Pain Questionnaire (SF-MPQ) was created to streamline the process. The SF-MPQ focuses mainly on pain intensity and includes a smaller set of key descriptors, making it quicker to administer while still leveraging the MPQ’s core idea of multidimensional assessment[9].
Another important multidimensional tool is the Wisconsin Brief Pain Questionnaire (BPQ). The BPQ was originally designed to assess pain in cancer patients, but its utility is broad[4][10]. Patients answer questions about the location of pain, its severity, and how it interferes with daily activities. A great advantage of the BPQ is that it can be given to a large number of patients easily and can collect both quantitative ratings and qualitative descriptions of pain[10]. In fact, the 2017 review notes that the BPQ is arguably one of the best clinical pain measurement tools because of its versatility and ease of administration[10]. For oral surgeons tracking chronic orofacial pain outcomes, tools like the BPQ or MPQ provide rich information – but they are usually not necessary for routine acute pain after a straightforward procedure.
Unidimensional Pain Scales (Acute Pain)
Unidimensional pain scales focus on a single aspect of pain – typically the intensity. These are the familiar 0–10 or “how bad is your pain?” types of scales. In the context of OMFS, unidimensional scales are most often used for acute pain, such as the pain right after surgery or a traumatic injury[5]. They are favored in these scenarios because they are simple, quick, and easy for patients to understand even when they’re in distress[11].
The most widely used unidimensional tool in both research and clinical practice is the Visual Analog Scale (VAS). A VAS usually consists of a 10 cm straight line on paper (or a digital line on a screen) with labels at each end – for example, 0 = “no pain” and 10 = “worst imaginable pain”[12][13]. The patient marks a point on the line that corresponds to their pain level, and the distance from the zero point is measured to get a score out of 100. In dental and OMFS studies, the VAS has been highly reliable and sensitive for assessing acute pain in adults[14][15]. It’s sensitive to small changes in pain intensity, which is useful for tracking improvement or deterioration[14]. In fact, the review recommends the VAS for measuring pain before and after surgeries as it provides consistent data for comparison[14]. Patients also find it intuitive – it’s essentially “mark on this line how much you hurt.” However, one practical issue with the VAS is that it typically requires the patient to see and mark on a physical scale (or screen), which can be less convenient in some settings (e.g. phone consultations or for patients with poor eyesight)[16].
A closely related tool is the Numeric Rating Scale (NRS). The NRS simplifies things even further: instead of marking a line, the patient is asked to pick a number from 0 to 10 that best represents their pain (0 = no pain, 10 = worst pain). Clinically, many OMFS providers use the NRS because it can be done verbally – you can ask the patient over the phone or when they’re waking up from anesthesia, “rate your pain from zero to ten.” This ease of administration is a big plus[17]. The trade-off is that the NRS, being an integer scale, is a bit less sensitive than the continuous VAS; some studies found that NRS scores can slightly under- or overestimate pain compared to VAS measurements[18]. Nonetheless, research shows a strong correlation between a patient’s NRS and VAS scores[17]. In other words, a “7 out of 10” pain on NRS usually falls in the corresponding range on a VAS line, so for practical purposes NRS and VAS convey similar information. Given its convenience, it’s no surprise that some oral surgery researchers use the NRS for adult patients[19] – especially when a quick assessment is needed – even though the VAS remains the more “gold standard” tool in controlled studies.
Another unidimensional method is the Verbal Rating Scale (VRS), which uses words instead of numbers. For example, a typical VRS might have the patient describe their pain as “none,” “mild,” “moderate,” or “severe.” Each category corresponds to a level of pain. The VRS is very straightforward and can even be administered remotely (say, by a phone call or mail questionnaire)[20][21]. This can be useful if, for instance, a nurse calls a patient the day after surgery and asks them to choose a description of their pain. However, the simplicity of VRS comes at a cost of precision. Pain categories are broad and not evenly spaced – the difference between “moderate” and “severe” isn’t a precise interval, so you can’t treat VRS data like continuous numerical data[21]. Statistical analysis of results can be limited because these are essentially rankings, not measurements on a uniform scale[21]. Despite that, a VRS can quickly flag if someone’s pain is in the higher range (e.g., “severe”) and may warrant a closer look or intervention.
Suggested alt text: “Wong-Baker Faces Pain Rating Scale with six cartoon faces ranging from a smiling face at 0 (no hurt) to a crying face at 10 (hurts worst).”
One of the most recognizable pain scales – especially in pediatric and geriatric care – is the Faces Pain Scale, including variants like the Faces Pain Scale-Revised (FPS-R) and the Wong-Baker Faces Pain Rating Scale (WBS). These are unidimensional in that they ultimately give a pain intensity score, but they present it visually using facial expressions instead of numbers. For example, the Wong-Baker scale shows a series of six cartoon faces from a happy face at “0 – no hurt” to a crying face at “10 – hurts worst”[22][23]. We often use or refer to face scales when dealing with children, because young kids might not grasp the 0–10 concept but can point to the face that best matches how they feel. Research confirms that children (especially over age 5) find it easier to communicate pain with a faces chart than with numeric scales[24]. These scales are also very useful for patients with language barriers or cognitive impairments – anyone who may struggle to quantify their pain in words or numbers can usually identify with a facial expression. The WBS in particular is widely used for children and also suggested for older adults[25][26], because standard 0–10 scales may be confusing or abstract for them, potentially leading to overestimation or underestimation of pain if they misinterpret the scale[25]. By using facial expressions that universally convey discomfort, the face scales help bridge that communication gap. (For very young children, aged around 3–5, even the faces can be tricky if there are too many options, but the revised versions with fewer faces or clearer differences have addressed this to some extent[27].) In our practice, we have found that a quick glance at a faces chart can immediately tell us if a child is “okay” or really hurting, without them needing to explain in words.
Lastly, a unique tool worth mentioning is the Full Cup Test (FCT) – an unconventional yet clever pain scale. The FCT presents the image of a cup. Patients draw a line in the cup to represent how full of pain the cup is: an empty cup means no pain, a full cup means worst pain, and anything in between is partial filling[28]. The result is taken as a percentage of the cup filled. This simple visual metaphor doesn’t require any numbers or complicated instructions. Studies have suggested the FCT can be useful for patients with low literacy or those who find numerical scales confusing[29]. We might not use the FCT often in a typical oral surgery office, but it’s a good reminder that pain assessment can be made as basic as a drawing – the key is to adapt to what the patient understands best.
In summary, OMFS professionals have an arsenal of pain measurement scales at their disposal. Multidimensional scales (MPQ, SF-MPQ, BPQ, etc.) give a broad view of chronic pain, capturing its nuances, while unidimensional scales (VAS, NRS, VRS, FPS, WBS, FCT) provide quick snapshots of pain intensity, ideal for acute post-operative scenarios[30]. The 2017 review concluded exactly this: multidimensional tools are suited for chronic pain, whereas one-dimensional tools are more appropriate for acute pain after surgeries like third molar extractions[30]. In the next section, we’ll see how these scales are actually applied in post-operative pain management research and practice.