Dry socket is considered as one of the most common complications of tooth extraction and is characterized by severe pain, halitosis and destruction of the blood clot,^1,2 starting usually on the second or third day postoperatively. Its prevalence has been reported to vary from 0% ³ to more than 35% ⁴ and is more common following mandibular third molar extraction.^5-11 Patients experience pain and may experience loss of productivity. This makes the condition costly to both the patient and the society, as 45% of patients require multiple postoperative visits in the process of managing this painful condition.12

The exact pathogenesis of dry socket is not well understood, however, disintegration of the blood clot by fibrinolysis remains the most widely accepted theory.¹³ Several contributing factors had been reported to be associated with an increased risk of dry socket. They include traumatic extraction,^2-4,11 preoperative infection,^11,12 smoking,¹³ gender,^11,14 site of extraction,^8,14 use of oral contraceptives,¹⁵ and many other factors. Efforts have been made to define the condition more accurately through the use of the terms such as alveolar osteitis, alveolitis, localized osteitis, localized osteomyelitis, post extraction osteomyelitis syndrome, alveolalgia, alveolitis   sicca   dolorosa,   a   vascular socket, leeren alveole, necrotic socket and fibrinolytic alveolitis. However, the term dry socket is still the most common term used for this condition.^{7, 13}

Although not the rule, some authors do not accept speaking of dry socket treatment as long as its etiology is not properly known. The treatment can only aim to control the pain during the period of cure of the affection and this is mainly achieved by means of palliative measures.¹⁶ The treatment modalities that have been proposed by many authors ^{17, 18} include the following:
1.    Pain reducing dressings, including traditional remedies such as zinc oxide-eugenol packs
2.    Anti-infective agents
3.    Anti-fibrinolytic agents
4.    Surgical intervention to remove necrotic material and to form a new blood clot. The most widely used technique to relieve pain of dry socket is the traditional methods of normal saline irrigation and placement of one of the available commercial dressing such as Alvogyl® iodoform dressing along with prescriptions of analgesics and systemic antibiotics for some patients. However, whatever the treatment modality prescribed, the patient is usually required to attend the clinic several times for the purpose of irrigation and redressing till complete resolution takes place.¹⁸

Hyperbaric oxygen therapy (HBOT) is a treatment modality during which a patient breathes 100% oxygen inside a closed chamber pressurized above 1 atmosphere absolute (ATA).¹⁹ The concentration of oxygen in the atmosphere is 21%. At 1 ATA, the oxygen in blood is almost entirely carried by hemoglobin. Because hemoglobin is approximately 97% saturated under normal conditions, increasing greatly the oxygen-carrying capacity of blood by increasing hemoglobin saturation is not possible. Inhalation of HBO can enhance the amount of oxygen carried in blood by increasing the quantity of oxygen dissolved in the plasma.

Oxygen has a solubility of 0.014/mL of plasma at 1 ATA and 37°C. At 1 ATA, the amount of dissolved oxygen in 100 ml of plasma is 0.449 ml which can be increased to approximately 1.5 ml when breathing 100% oxygen at normobaric (ambient) pressure. When inhaling 100% oxygen at 3 ATA, the amount of dissolved oxygen in 100 ml of plasma increases to 6.422 ml, which is enough to meet the basic metabolic needs of the human body.^{20, 21}

The driving force for oxygen diffusion from the capillaries to the tissues can be estimated by the difference between the partial pressure of oxygen on the arterial side and the venous side of the capillaries. The difference in the partial pressure of oxygen from the arterial side to the venous side of the capillary system is approximately 37 times greater when breathing 100% oxygen at 3 ATA than air at 1 ATA.²²

Many authors ^22-24 reported the following benefits during applying HBOT:

1. The increased oxygen diffusion levels during HBOT ends up in an increase in the tissue oxygenation. Thus, it can support poorly perfused and hypoxic areas.
2. Increased tissue oxygenation enhances polymorphonuclear cell bactericidal activity.
3. HBOT alone is bactericidal to strictly anaerobic organisms and bacteriostatic to many microaerophilic organisms and some species of Escherichia and Pseudomonas.
4. Oxygen concentrations can increase some antibiotics activity especially those who do not work properly in an anaerobic environment.
5. Increasing tissue oxygenation in abnormally low tissue oxygen has been shown to accelerate healing by increasing the fibroblast synthesis of collagen matrix which is essential for neovascularization by capillary in-growth in hypoxic or poorly perfused tissues, and this is of clinical importance when treating many conditions as in case of irradiated tissues.