From Volume 50, Issue 2, February 2023 | Pages 131-133
Cow's milk is considered one of the gold standard storage media for avulsed teeth, and it is readily available. However, with the high prevalence of allergy to this milk, there is a potential danger of anaphylaxis when used as a storage medium. Its use and that of alternative storage media is discussed.
CPD/Clinical Relevance: There is a potential for anaphylaxis when cow's milk is used as a storage medium for an avulsed tooth.
There are many recommended media for the immediate storage and transportation of avulsed permanent teeth following dental trauma.1 Cow's milk is considered one of the gold standard storage media, and is readily available.1,2 However, there is a high prevalence of allergy to cow's milk in children, which is estimated to be 0.25-4.9% worldwide, with approximately 1 in 40 children affected within the UK.3 This article highlights the potential danger with regard to cow's milk as a storage medium for avulsed permanent teeth and discusses alternative storage media.
A 7-year-old male was referred to the Community Dental Service for urgent trauma review and prosthodontic management. Medically, the patient had a dairy allergy, but was otherwise fit and well. History taking revealed that he had suffered a facial and dental injury while playing football, which resulted in avulsion of a permanent maxillary central incisor. The avulsed tooth was not replanted at the scene of injury, but was placed in milk for circa 90 minutes while seeking emergency care. At the local accident and emergency department, the tooth was rinsed with saline and then replanted. However, the tooth was promptly removed when the patient began to experience wheezing, urticaria, pruritus and significant distress. He was immediately transferred to the resuscitation department and treated for anaphylaxis.4 The source of anaphylaxis was attributed to trace amounts of milk on the tooth. No further attempts to replant this tooth were made.
This case identifies the importance of considering allergy with tooth storage media following avulsion and what alterative storage media are available.
Cow's milk allergy (CMA) is one of the highest prevalent allergies in children, with approximately 1 in 40 children affected in the UK.3 To put this into context, it has a similar prevalence to that of peanut allergy.5 CMA is an immune-mediated reaction to proteins within milk and is categorized according to the underlying immune-mediated mechanism. They are classified as immunoglobin E (IgE) mediated, non-IgE or as a combination of the two.6 CMA is an allergy that is often outgrown in adulthood. The reason for this is not fully understood. 7
Avulsion is considered one of the most severe forms of dental trauma. It is the complete displacement of the tooth from its socket. Tooth avulsion accounts for 0.5-16% of all dental injuries.8·9 A systematic review revealed that the most frequent location for dental trauma to occur was at home, followed by at school and then in the street.10 Replantation of permanent teeth at the time of the injury is important to improve the chance of a favourable outcome; however, this is not always possible for many reasons. When replantation is not feasible at the time of injury, the tooth should be placed in a storage medium. This should take place immediately to avoid dehydration of the root surface. A variety of storage media has been suggested.1
The International Association of Dental Traumatology (IADT) recommend the use of cow's milk, Hank's balanced salt solution (HBSS), saliva or saline in descending order of preference, as suitable and convenient storage media.1 The British Society of Paediatric Dentistry (BSPD) guideline for tooth avulsion of permanent teeth in children suggests that ‘if immediate replantation is not possible, place the tooth in a vessel containing suitable storage media: in order of preference: milk, physiological saline or saliva’.11 Both guidelines recommend cow's milk in the first instance as a suitable and convenient storage medium.
Cow's milk is considered an acceptable storage medium owing to its physiological pH (6.5-7.2) and osmolality. It also possesses essential nutrients, while lacking active toxic components.13 PDL cells have been shown to survive for up to 24 hours, with low fat and chilled milk preferred for maintaining cell vitality.14 Furthermore, it is also usually readily available and is often considered the gold standard against which other storage media are referenced.13,14
HBSS is a sterile, physiologically balanced isotonic standard salt solution. PDL cells have been shown to survive in HBSS for up to 48 hours.15 This is often considered another gold standard, along with cow's milk, and used as a comparison reference for other storage media. HBSS however, is not readily available in the UK. In the US, ‘Save-A-Tooth’ boxes are available for purchase. These contain HBSS and enable schools, parental homes and other facilities to have an appropriate storage medium for an avulsed tooth if required.16 The authors of this article have been unable to find the equivalent available for sale in the UK.
Despite being the most readily available, saliva is not a very effective storage medium. This is due to its non-physiological osmolality and high content of enzymes and micro-organisms.17 As such it, it is not recommended for use for longer than 30 minutes’ storage.18
This is an isotonic solution and has a comparable pH with PDL cells. It lacks nutrients and cannot maintain the metabolism of the PDL cells. It has been advised that it is not appropriate storage medium for longer than 10 minutes’ use.19,20
A survey in the UK suggested that non-dairy or plant-based milks are increasing in popularity, with almost a quarter of the population consuming them.21 Studies on the potential of non-dairy milks as an appropriate storage medium for avulsed teeth have been carried out, with the main focus on soy milk.22,23
There have been multiple studies concluding that soy milk can be a suitable alternative storage medium for avulsed teeth.22,23 Soy milk contains a high content of proteins, amino acids, vitamins and minerals, which are essential for cell maintenance and growth. Soy milk also possesses a physiological pH and osmolality.23 However, it is important to note the risk of a cross-allergy with a high proportion of people with an allergy to cow's milk similarly having an allergy to soy milk.24
There are very few studies that have investigated almond milk as a storage medium. In vitro studies have identified it to be inferior to that of low fat cow's milk in terms of PDL cell viability.24 It is also important to note that many people are allergic to tree nuts, such as almonds.25
The IADT suggested that, after cow's milk, the descending order of preference for storage media is: HBSS; saliva; or saline, which are suitable and convenient storage media.1 Whereas the BSPD guidelines for tooth avulsion of permanent teeth in children suggest that ‘if immediate replantation is not possible, place the tooth in a vessel containing suitable storage media – in order of preference: milk, physiological saline or saliva’.11 HBSS is not mentioned by the BSPD guidelines, which is most likely to be due to its lack of availability in the UK, rather than its properties as a storage medium.
Cow's milk is often considered the storage medium of choice for avulsed teeth when replantation is not possible at the scene of injury.12,9 This is due to its availability, low cost and its ability to maintain the vitality of PDL cells.12,16 However, we must be cautious when suggesting this as a storage medium due the high prevalence of cow's milk allergy in the population. 3 As a dental professional when providing telephone advice it is essential that the medical history is checked prior to suggesting a suitable storage medium. If the patient has a cow's milk allergy, an alternative storage medium should be suggested.
With the increasing popularity of plant-based milks, and with further research into these as appropriate storage media, there may be a time when plant-based milks are also recommended as suitable storage media in guidelines. As plant-based milks can also be allergenic, caution with their use is advised.
The authors suggest that current guidelines could be reviewed to consider, or highlight, the potential risk of allergy. Furthermore, we recommend that a question on cow's milk allergy be added as routine item when giving telephone advice on avulsion injuries of permanent teeth, to ensure a suitable storage medium is used and possible anaphylaxis averted.
