Art of Prevention: The importance of tackling the nail-biting habit!

Onychophagia is defined as a chronic habit of biting nails, commonly observed in both children and young adults, and it is classified among nail diseases caused by repeated injuries. During my TMJ course, many of you have heard me discuss the role of parafunctional habits, such as nail biting, pencil chewing, prolonged thumb or finger sucking, lip biting, or chewing the inside of the cheek, can lead to temporomandibular disorders and/or headaches.


The hard habit of nail-biting

In this blog, I am just going to focus on nail-biting, particularly as it is a very, very hard habit for most to break. I always encourage my course participants to look at their patient’s hands and see if they bite their nails, cuticles, or knuckles. Often, I found this type of parafunction can lead to temporalis headaches. So, one objective sign of course would be tenderness to palpation of the temporalis muscle on one or both sides, or intraorally on the insertion point of the temporalis muscle onto the coronoid process. In addition, the masseter muscle can also be tender. Finally, one of the reasons I still teach the Rocabado Pain Map is to help TMD Clinicians outline and palpate the location of the various synovial tissues surrounding each temporomandibular joint, in addition to the lateral pole of the condyle.

Pattern of Nail bitters

Overall a consistent and classic series of objective patterns I see with my nail or cuticle biters are tenderness of unilateral or bilateral Temporalis musculatures (often consistent with the location of their headaches) and tenderness of the Anterior Superior synovial tissues given the nail biting is predominantly a protrusive or lateral protrusive movement(see middle photo). If we can pick these subtle features up early during our exam, possibly we can limit and control the potential development of going from a muscular and synovial pain problem, and avoid the patient becoming a disc displacement with reduction or without reduction.

The main goal of our objective assessment and observations is to be preventative! We also know to screen for systemic hypermobility as well, and we know from the literature that those with systemic hypermobility and particularly hypermobility of one or both Temporomandibular joints, along with a type of parafunction like nail biting, tend to go on to develop temporomandibular disorders.

Prevalence and etiology

The current literature estimates the prevalence of nail-biting at 20% to 30% of the general population (Halteh et al., 2017, Pacan et al., 2014). Nail biting is more prevalent in children, with one study noting a 37% prevalence among individuals aged 3 to 21 years (Winebrake et al., 2018) Leung and Robson (1990) describe a downward trend in prevalence as affected individuals reach adulthood and beyond. However, nail biting remains prevalent among young adults, with one study reporting a 21.5% prevalence among those aged 18 to 35 years (Halteh et al., 2017). There are inconsistencies regarding differences in prevalence based on sex, with studies reporting anywhere from a higher predilection in boys to a higher female predominance and some studies even report no difference (Leung and Robson, 1990, Pacan et al., 2014). Onychophagia is usually not observed before the age of 3 or 4 years.

To date, the exact etiology of onychophagia or nail-biting remains as yet unclear. Although it has been observed that nail biters have more anxiety than those who do not have the habit, no relevant relationship was found between nail biting and anxiety. Others support that onychophagia is a learned behavior from family members, which most likely seems consistent with a process of imitation.

Phases of Nail-biting

Nail biting is genuinely a sequence of 4 distinct phases. Once the finger has been inspected visually or felt by palpation by another finger, the hands are then placed close to the mouth. Subsequently, the mandible is placed in a laterotrusive (or just lateral) edge-to-edge contact position (see middle photo); then, the fingers are quickly tapped against the front teeth followed by a series of quick spasmodic biting actions. In this case, the patient will have his fingernails pressed tightly against the biting edges of the teeth. And finally, the fingers are withdrawn from the mouth.

To date, several treatments have been proposed to manage nail biting. Some of them focus on the psychological aspect of this oral habit aiming to obtain a behavioral change such as psychotherapy or pharmacotherapy. Others focus on target areas as they fetch solutions to keep the hands away from the mouth among which the application of bitter-tasting nail polish or the use of an occlusive dressing on fingertips is mainly cited.

Adversive Therapies

Dermatologists may recommend a form of aversive therapy to patients by applying a distasteful coating over the nail to discourage patients from biting. You can find some of these on Amazon by the name of Mavala or Stop The Bite. This method has shown improvement in reducing impulsive nail-biting behavior; however, the method should be avoided for patients suffering from an underlying compulsive disorder (Koritzky and Yechiam, 2011). In addition, olive oil has been shown to decrease biting behavior by making the nail feel softer without causing distress to the child (Isaacs, 1935). Alternative topical products include 1% clindamycin, quaternary ammonium compounds, and 4% quinine suspended in petroleum (Tosti and Piraccini, 2000). For patients suffering from severe nail dystrophy, using an adhesive bandage to cover the injured fingers and nails can help prevent further damage. Again, on amazon, you could try gel finger cots vs. bandages.

Cognitive Behavioral Therapy for Nail-biting

Another therapeutic approach is done by using cognitive behavioral therapy to address the intrusive behavior. Cognitive behavioral therapy is based on both the behavior and a cognitive model and mechanistically works to limit maladaptive coping behaviors (Rothbaum et al., 2000). Historically, a limited number of case reports describe the use of aversive hypnosis to effectively reduce chronic nail biting (Leshan, 1942). Most recently, Bornstein et al. (1980) proposed a combination of hypnotherapy with behavioral modification to improve habitual nail biting and promote remission. A token economy is used to encourage positive behaviors through reinforcement with rewards (Ivy et al, 2017).

Habit Reversal Therapy 

On the other hand, habit reversal therapy (HRT; e.g., chewing gum rather than biting nails during impulsions) provides patients with a way to form awareness of the habit and alternative methods to cope (Woods et al., 1999). HRT includes three components: Awareness training, competing response training (e.g., gum chewing rather than nail biting), and a social support system (Magid et al., 2017). Twohig et al. (2003) reported a significant increase in nail length when using HRT compared with a placebo.

Aversive therapy under the guidance of a professional may provide nail-biting relief as well. Silber and Haynes (1992) compared the use of a competing response (e.g., clenching first for several minutes to produce discomforting tension) and the application of a bitter substance to the nails, showing a significant improvement in nail length with the competing response group. This modality must be correctly used because shaming and punishment for nail biting are associated with adverse outcomes, potentiates the compulsion, and are not recommended as a treatment service line (Tanaka et al., 2008).

Aversive therapy can be a component of a three-step behavior modification technique known as stimulus control procedures (Magid et al., 2017). The three steps involve removing environmental triggers (e.g., splintered cuticles), increasing the difficulty to bite nails (e.g., bandaging fingers), and removing positive reinforcements (e.g., adding aversive substance to the nails).

Practical intervention pearls

Proper nail hygiene

Proper nail hygiene is essential and includes keeping the nails trimmed and filed. Interestingly, allowing professionally manicured nails may keep adolescents engaged in not biting their nails secondary to positive cosmetic appeal (Tanaka et al., 2008). Nail cosmetic products may act as both a treatment for nail biting and a method to mask severe nail dystrophy while the nail is healing (Iorizzo et al., 2007).

Gum chewing

Gum chewing may be an effective alternative option to curb the compulsion to bite nails in socially stressful situations for an older child when other coping mechanisms cannot be utilized. This results in better oral hygiene and is (Massler and Malone, 1950). Sorbitol-based gum rather than a sugared variety can help prevent caries (Ly et al., 2008).

Books and social media

Books and social media can provide support and strategies. One great resource for addressing a child’s nail biting is using the interactive book titled What to Do When Bad Habits Take Hold by Dr. Huebner, 2008. This book creates a unique and fun self-exploration in identifying bad habits, such as nail biting, to bring self-awareness, followed by tips and tricks to curb the habit. For children who prefer a more visual approach, an episode of the Bernstein Bears creatively addresses nail biting in a comfortable and enlightening episode and can be streamed for free on YouTube (YouTube, 2014).

Reward system

Parents also can apply token economy to curb nail-biting behavior. Creating a sticker chart for children and adding a sticker each day the child keeps nails free from biting damage keeps children motivated, knowing that a prize is available after multiple good days in a row (e.g., 2 weeks straight to begin with). Children with bedwetting have successfully been treated using a similar strategy (Ortiz and Garzon, 1978).

Mindfulness techniques

Bringing awareness to the habit can help create self-awareness and search for socially acceptable ways to cope with stress and anxiety. Cognitive therapy suggests that persons engage in alternative behavior to distract from intrusive impulsions, such as arts and crafts, sports, and musical instruments, to improve confidence and focus and reduce distress (Massler and Malone, 1950). Furthermore, nail biting may be a source of transmission for viruses and bacteria (e.g., touching a communal water fountain spigot and then transferring fingers to the mouth). The coronavirus that caused the coronavirus disease of 2019 was shown to remain on surfaces for up to 3 days (van Doremalen et al., 2020). As a consequence, strong recommendations to avoid face touching would also apply to the recommendation to stop nail-biting behavior.

I hope some of this information is useful and allows those you know or treat to stop biting their nails. I welcome any feedback on strategies you have found to help stop nail biting, so we can continue to provide relief to our patients suffering from temporomandibular disorders.
All the best!

1. O. M. Tanaka, R. W. F. Vitral, G. Y. Tanaka, A. P. Guerrero, and E. S. Camargo, “Nailbiting, or onychophagia: a special habit,” American Journal of Orthodontics and Dentofacial Orthopedics, vol. 134, no. 2, pp. 305–308, 2008.
2. P. A. Deardoff, A. J. Finch Jr., and L. R. Royall, “Manifest anxiety and nail-biting,” Journal of Clinical Psychology, vol. 30, no. 3, p. 378, 1974
3. M. Massler and A. J. Malone, “Nail biting-a review,” American Journal of Orthodontics, vol. 36, no. 5, pp. 351–367, 1950.
4. O. Marouane, M. Ghorbel, M. Nahdi, A. Necibi, N. Douki, “New Approach to Managing Onychophagia”, Case Reports in Dentistry, vol. 2016, Article ID 5475462, 5 pages, 2016.
5. Baghchechi M, Pelletier JL, Jacob SE. Art of Prevention: The importance of tackling the nail-biting habit. Int J Womens Dermatol. 2020 Sep 17;7(3):309-313.

Michael Karegeannes
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