الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
In the past several years, the use of 3D CBCT has steadily increased in oral and maxillofacial surgery and implant dentistry compared with the medical CT technology. The greatest advantage of CBCT imaging is that it allows the surgeon to obtain the same vital 3 dimensions (3D) anatomic information without exposing the patient to high level of ionizing radiation.
It is widely accepted that high-dose radiation is carcinogenic. However, some researchers postulated that low dose of radiation could be harmless and even have a positive effect.
Routine diagnostic X-rays (e.g., chest X-rays, mammograms, computed tomography scans) and routine diagnostic nuclear medicine procedures using sparsely ionizing radiation forms (e.g., beta and gamma radiations) stimulate the removal of precancerous neo-plastically transformed and other genomically unstable cells from the body (medical radiation hormesis).
The indicated radiation hormesis arises because radiation doses above an individual-specific stochastic threshold activate a system of cooperative protective processes that include high-fidelity DNA repair/apoptosis (presumed p53 related), an auxiliary apoptosis process (PAM process) that is presumed p53-independent, and stimulated immunity. These forms of induced protection are called adapted protection because they are associated with the radiation adaptive response.Cone beam computed tomographic (CBCT) became one of the routines popular dental diagnostic modalities; the average person could have multiple exposures.The CBCT systems used by dental professionals rotate around the patient, capturing data using a cone-shaped X-ray beam. These data are used to reconstruct a three-dimensional (3D) image of the following regions of the patient’s anatomy: dental (teeth); oral and maxillofacial region (mouth, jaw, and neck); and ears, nose, and throat (“ENT”).
The amount of radiation received from a cone-beam CT of the jaws will vary from approximately 18–200 µSv depending on the size of the field of view, resolution of the images, size of the patient, location of the region of interest, as well as the manufacturer settings.
The amount of radiation received for a cone-beam CT is minimal in comparison to what we receive being alive on the earth.
A cone-beam CT can be a very useful tool in planning your dental treatment and your dentist will only use this tool when the benefits of the examination outweigh any of the minimal risks
The major salivary glands are the parotid glands, submandibular glands and sublingual glands as Minor salivary glands are situated on the tongue, palate, and buccal and labial mucosa. They are small mucosal glands with primarily a mucous secretion. The working part of the parotid glands are “serous” glands, for their acinar cells contain only serous secreting cells, salivary gland tissue consists of the secretory end pieces (acini) and the branched ductal system whose secretions are devoid of mucin compared to that of the submandibular and sublingual glands, which contain both serous- and mucin-secreting cells, (Whole saliva is an important fluid that contain a highly complex mixture of substance. It is secreted primarily by three paired major salivary glands and secondarily by hundreds of minor salivary glands located below the mucosal surfaces of the mouth. Salivary gland secretions contain locally produced proteins, as well as molecules from the systemic circulation
Saliva contains several effective buffering systems that can help maintain a normal pH when acidic foods and beverages are introduced. There protect oral tissues against acidic attack. When swallowed, these buffers protect the esophagus, helping neutralized the reflux acid of conditions such as heartburn and hernia. Saliva plays a vital role in dental health as patients strive to maintain a healthy dentition throughout their lives, it is the primary
growth environment for the flora of the oral cavity. As the physio-chemical properties of the saliva are changed, this affect what microorganisms will grow in the mouth In terms of mineral loss, if the environment of the mouth is acidic, the mineral loss is likely to occur, however, if the environment has an alkaline pH, then the gain of mineral is equally possible and in this context it is important to recognize that saliva is the major reservoir from which this mineral comes In the mouth, which has a consistently low salivary pH at rest, it is not unusual to see recurrent caries, accelerated tooth wear, dent erosion, and candida albicans infection
Optimal pH for saliva is above 7.2 to 8.4. A reading consistently lower than 6.8 is indicative of possible insufficient alkaline reserves. After eating, the saliva pH should rise to 7.8 or higher. Unless this occurs, the body has alkaline mineral deficiencies (mainly Calcium and Magnesium) and will not assimilate food very well. The lower your pH value below 7.0, the greater your degree of acid stress. Continue testing and recording your pH for a few weeks – first thing in the morning, afternoon and at bedtime (This will show your body pH trend). While generally more acidic than blood, salivary pH mirrors the blood (if not around meals) and is also a fairly good indicator of health
50 patients were participating in this study. They were aged between 18 and 55 years. They were selected from the Oral and Maxillofacial Surgery Department clinics of the Faculty of Dentistry, Ain Shams university in the period started from May 2018 to May 2020. They were subjected to ionizing radiation (CBCT) as diagnostic tool for various periodontal pathological conditions.
The cumulative effect of radiation to the patients could be examined in further research, as well as long term effect of digital diagnostic CBCT oral health.
CONCLUSIONS & RECOMMENDATIONS
Conclusion
Monitoring human individuals exposed to low-dose low dose of radiation is important but will not provide enough information about its possible Hormesis effects. A well-organized large-scale animal experiments will be more beneficial. Low-dose exposures were reported to extend the lifespan of mice and some invertebrates. This study could not be applied to humans (Benderitter et al., 2007). In the present study, there were no changes observed to the low dose radiation of the CBCT. The cumulative effect of radiation to the patients could be examined in further research, as well as long term effect of digital diagnostic CBCT oral health.
A good alternative for such study in humans would be large-scale animal experiments where life span duration is known to be a sensitive endpoint attributable to radiation exposures, which could not be tested in humans. In well-organized animal study, low-dose exposures were reported to extend the lifespan of mice and some invertebrates (Benderitter et al., 2007). One of hot topics of study is to clarify in vivo, whether relevant doses cause an increase in cell death. The monitoring of populations exposed to low-dose low-rate radiation is important but will hardly add much reliable information on the health risks (Sergei, 2
Recommendations:
from this study the time interval of the radiation dose received over a long period of time is needed to be investigated in future studies. Larger sample size and multicenter studies are recommended to study possible positive effect of single Digital CBCT images on oral health. This includes the cumulative effect of several CBCT on oral mucosa. It can be reasonably assumed that the screening, increased attention of exposed people to their health, and biased research will result in new reports on the elevated detection rate of cancer and other diseases in exposed populations. (Colceriu-Şimon et al., 2019).
from this study, it is recommended to examine the delayed action of the diagnostic CBCT after several hours or days, as well as the effect of Diagnostic CBCT on normal flora and pathogenic microorganisms.