**1. Introduction**

Obstructive Sleep Apnea (OSA) was described as early as 1837 in "The Posthumous Papers of the Pickwick Club". Dickens, a British author, described "Joe", the main character, as a fat boy who falls asleep easily and involuntarily (Figure 1). [1]

In The Pickwick Papers (c. 1836–1837)

**Figure 1.** Artist (Hablot Knight Browne- Phiz) rendering of Joe, Charles Dickens' character.

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

Later on, Osler (1914) used the term "Pickwickian syndrome" to describe obese and sleepy patients, in homage to Dickens' character "Joe". As early as 1956, Bickelmann et al [2] reported that the "Pickwickian syndrome" was associated with extreme obesity and alveolar hypoventilation.

Gastaut's research group described three different types of apnea, namely, obstructive apnea central apnea, and mixed apnea. In 1973, Guilleminault introduced the apnea-hypopnea index (AHI), which refers to the total number of apnea and hypopnea episodes per hour of sleep, and proved, along with Dement, that obesity is not a prerequisite for OSA. In 1977, Guillemi‐ nault and Dement used the term "sleep apnea syndrome", in association with hypertension and electrocardiographic pathologies. [3]

Recently, much research on OSA has been conducted with a view to help elucidate the characteristic features of OSA. Sleep is a process through which the body restores energy used during the day. Not much is known about its biological purpose, but its evaluation can be undertaken by muscle and brain electrical activity, and ocular movement. Good-quality sleep entails several functions; these include physical recovery, biochemical refreshment, memory consolidation and psychological well-being. [4]

In adults, sleep is regulated by a cycle of five periods. The first four periods belong to nonrapid eye movement sleep (light and deep stage) and the fifth period is named the rapid-eyemovement (REM) or paradoxical sleep (active stage). The progression from the first stage to the RAM constitutes one sleep cycle. Generally, there are four to six sleep cycles per night; during which activities of the brain, muscles, and the cardio-respiratory system fluctuate (Figure 2, 3). [4]

**Figure 2.** A sleep cycle (non-REM to REM stages). [4]

During these sleep stages, several sleeping disorders can occur. International classification of Sleep Disorders (ICSD-3), revisited in 2014, includes the following broad categories: [5]

**Figure 3.** Consecutive wave of non REM to REM sleep cycles (I to IV). Throughout the night, REM becomes longer than slow wave sleep (stage 3and 4). MT: movement time, WT: wake time. [4]

**•** Insomnia

Later on, Osler (1914) used the term "Pickwickian syndrome" to describe obese and sleepy patients, in homage to Dickens' character "Joe". As early as 1956, Bickelmann et al [2] reported that the "Pickwickian syndrome" was associated with extreme obesity and alveolar

Gastaut's research group described three different types of apnea, namely, obstructive apnea central apnea, and mixed apnea. In 1973, Guilleminault introduced the apnea-hypopnea index (AHI), which refers to the total number of apnea and hypopnea episodes per hour of sleep, and proved, along with Dement, that obesity is not a prerequisite for OSA. In 1977, Guillemi‐ nault and Dement used the term "sleep apnea syndrome", in association with hypertension

Recently, much research on OSA has been conducted with a view to help elucidate the characteristic features of OSA. Sleep is a process through which the body restores energy used during the day. Not much is known about its biological purpose, but its evaluation can be undertaken by muscle and brain electrical activity, and ocular movement. Good-quality sleep entails several functions; these include physical recovery, biochemical refreshment, memory

In adults, sleep is regulated by a cycle of five periods. The first four periods belong to nonrapid eye movement sleep (light and deep stage) and the fifth period is named the rapid-eyemovement (REM) or paradoxical sleep (active stage). The progression from the first stage to the RAM constitutes one sleep cycle. Generally, there are four to six sleep cycles per night; during which activities of the brain, muscles, and the cardio-respiratory system fluctuate

During these sleep stages, several sleeping disorders can occur. International classification of Sleep Disorders (ICSD-3), revisited in 2014, includes the following broad categories: [5]

hypoventilation.

(Figure 2, 3). [4]

and electrocardiographic pathologies. [3]

362 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

consolidation and psychological well-being. [4]

**Figure 2.** A sleep cycle (non-REM to REM stages). [4]


Sleep apnea is the most common sleep disorder related to breathing. There are 3 types of sleep apnea: Obstructive, central, and mixed (a combination of both forms). Obstructive sleep apnea (OSA) is caused by partial or complete obstruction at multiple levels of the upper airway, producing reduction (hypopnea), or cessation (apnea) of airflow. Due to the lack of adequate alveolar ventilation, oxygen saturation may drop and partial pressure of CO2 may occasionally increase. Snoring and sleep fragmentation are common with OSA that can be graded as mild, moderate and severe.[6] Adults and children are equally affected. However, the prevalence, etiology and pathophysiology of the disorder differ from one group to another. It is important to note that the physiopathology and etiology of OSA are poorly understood.

Furthermore, OSA is associated with neuropsychological impairment, sexual dysfunction, metabolic and cardiovascular co-morbidities; and causes an increase in mortality. Quality of life and economic potential are also affected: snoring affects the sleeping pattern of the partner, and frequent arousals at night result in relative sleep deprivation and can cause excessive daytime sleepiness, loss of concentration and motor vehicle accidents.[4]-[7] Therefore, OSA is regarded as a public health condition and increases the consumption of health care resources.

Continuous positive airway pressure (CPAP) is considered a golden standard treatment; oral appliances and surgical procedures for upper airway soft tissues and maxilla-mandibular advancement are other alternatives. Hence OSA treatment requires a multidisciplinary management. [8] Orthodontists, sleep specialists and surgeons should all be involved in managing and treating OSA. This chapter gives a comprehensive account of the literature on OSA and underlines the role of orthodontists in managing OSA with a view to improve the physical, mental and social status of patients diagnosed with OSA.
