To meet the requirements of today’s modern dentistry, it is not enough just having healthy teeth and gums. It is necessary that both soft and bone tissues in the oral cavity to provide adequate volume and consistency. There always occurs a bone resorption after tooth extraction within the alveolar process, the bone support of the tooth. After a tooth extraction, in the first year there is a 25% resorption of the initial volume of the bone where the tooth was. Then, the bone continues to be slowly reabsorbed. Thus, three years after the extraction, the bone is resorbed at a rate of 40% -60%. Five years after the extraction, a bone which initially was 8 mm thick can have a thickness of less than 3 mm. Because of this, it is quite often required that the dental treatment also include a bone augmentation (or addition), especially when it concerns an area in the oral cavity which is very important in terms of physiognomy. Also, bone augmentation is necessary when you want to insert an implant in a high demand area in terms of mastication. By increasing the amount of available bone, an implant with a bigger length and diameter can be inserted, and this will have a greater stability and will thus be more responsive to mastication demand. Bone augmentation can be obtained through a surgery which can be done either within the same surgery with insertion of implants, or in a separate action depending on the severity of the default. Although bone augmentation surgery is a highly complex one, for the patient is as bearable as a routine dental surgery. Local anaesthesia is used before the surgery, and after the surgery the patient is given painkillers and thus the discomfort caused will be minimal.

The materials used for bone augmentation are the autogenous bone (the bone harvested from the patient to whom the bone addition is done), or the treated bone substitute, produced based on calcium phosphate, periodontal membrane etc.
The autogenous bone
It is harvested from the patient, from different regions, usually all in the oral cavity. During the surgery, the harvested bone graft is inserted into the area where the bone defect repair is desired. The patient’s own bone provides good results. The disadvantage of this method is that harvesting bone graft is necessary to make an additional incision and hence there is an additional trauma for the patient.
Animal bone substitute
The most used is the bovine bone. This is treated and sterilized, so that no rejection reactions or infections appear. Although it is believed that in operations involving bone addition, the added bone turns into the patient’s own bone, this concept is often false. After bone augmentation surgery, the own bone is usually stimulated to regenerate, while the added artificial bone provides only a matrix where the patient’s bone cells will be submitted. Following the bone addition surgery, as our own bone grows in size, the added artificial bone is resorbed and removed. The bone in the oral cavity is entirely surrounded by gum. After the addition surgery, it is very important that cells derived from gum do not penetrate the bone defect during the process of bone regeneration and then the newly formed bone quality to be very low. Different types of periodontal membranes isolating the bone defect and the artificial bone introduced by the gum are used to prevent this. Periodontal membranes can be resorbable (they are resorbed along with new bone formation) or non resorbable (they are removed by the doctor after the repair is completed).
In many situations, when the dentist performs an apparently commonplace extraction, it is possible that we are also recommended an intervention to increase the amount of bone – the bone addition. Within the complex dental treatment, it is preferable to perform a bone augmentation surgery too, to prevent alveolar bone resorption when we know that an implant is inserted instead of the lost tooth,