Reminder on the organization and physiology of bone tissue
- INTRODUCTION
Implantology has become a routine clinical procedure with reliable results. For this, the bone quantity must be sufficient in height and width in order to achieve osseointegration of the implants. This prerequisite is not always met. Indeed, some bone volumes do not allow the implants to be placed simply
- Upper jaw
- General morphology
The maxillary bone forms the main part of the facial mass, united on the median line by a horizontal apophysis with its contralateral counterpart, it limits with the latter the cavity of the nasal fossae; as it takes part in the formation of the walls of the orbital and oral cavities.
Although it is the largest bone, it is nevertheless the lightest because it is hollowed out by a large pneumatic cavity: the maxillary sinus, which is a vast pyramidal-shaped air cavity with a medial base, lined with respiratory mucosa. The dimensions of the sinus vary in infinite proportions from one subject to another, and often even between the right and left sinuses.
Reminder on the organization and physiology of bone tissue
- Innervation
- The sensory branch of the trigeminal cranial nerve (V) gives rise to the maxillary nerve (V2) whose main collaterals are:
- Pterygomaxillary nerves which branch into:
*Nasopalatine nerve which descends along the nasal septum then passes through the incisive canal (bunoid papilla), innervates the anterior ¼ of the palatine mucosa.
*Greater palatine nerve: In the greater palatine canal accompanied by the descending palatine artery, innervates the mucosa of the posterior 2/3 of the palate + soft palate and sends a branch which anastomoses with the nasopalatine.
- Alveolar nerves:
- Vascularization
Made up of the maxillary artery, terminal of the external carotid artery, it passes inside the region of the neck of the condyle then arrives in the pterygomaxillary fossa, and gives:
The posterior superior alveolar artery, i.e. 2 or 3 branches which divide into 2 contingents:
*Internal to vascularize the maxillary sinus mucosa and molars.
*External for the vestibule and gingiva of the molar region.
-The infraorbital artery which distributes to the entire infraorbital region.
-The greater palatine artery for the entire palatine mucosa.
-The sphenopalatine artery (terminal branch of the maxillary artery) which enters the incisive foramen
Reminder on the organization and physiology of bone tissue
- Lower jaw
- General morphology
Also called the lower jaw, this unpaired and median bone is the largest, the strongest and the only mobile bone in the face. It has three parts: the horseshoe-shaped body and the two ascending branches or mandibular ramus. These three parts are joined by the mandibular angles.
- The body presents:
- 2 sides:
- External which includes the chin holes.
- Internal where the geni processes and the mylohyoid line extend.
- 2 edges:
- Upper: seat of the alveoli.
Lower: very thick.
- The body presents:
- 2 sides:
- External which includes the chin holes.
- Internal where the geni processes and the mylohyoid line extend.
- 2 edges:
- Upper: seat of the alveoli.
Lower: very thick
- Innervation
The inferior alveolar nerve: the largest branch of the mandibular nerve (V3 – itself from the Trijumeau nerve), it is only sensory and goes directly towards the posterior orifice of the mandibular canal.
and ends in:
*incisive nerve;
*mental nerve;
* posterior alveolar nerve running in the retromolar canal responsible for the innervation of the molars and premolars
Reminder on the organization and physiology of bone tissue
- Vascularization
- Including:
– The inferior alveolar artery, a branch of the maxillary artery, which enters the mandibular canal and supplies branches to all the teeth at the level of the mental foramen, this artery divides into two:
*The chin branch which irrigates the soft parts of the chin.
*The incisive branch which irrigates the incisor-canine group.
– Branches of the facial artery such as:
*the submental artery (anterior surface of the incisor-canine region).
- Alveolar processes
The alveolar process, alveolar bone or periodontal bone refers to the extension of the maxillary and mandibular bones that form and support the dental alveoli. It is contiguous with the basal bone and cannot be distinguished from it. The alveolar processes are created at the same time as dental development and eruption. They are then gradually resorbed with the loss of the tooth or during a certain number of dental and periodontal pathologies.
- Bone organization
It is made up of compact bone cortices organized into external and internal cortices (alveolar wall) delimiting the interdental and interradicular septa which are histologically made up of trabecular bone crossed by Zuckerkandl and Hirschfeld canals allowing the passage of vessels and nerves.
- Bone physiology
Bone tissue, particularly alveolar bone, is in perpetual remodeling. Its physiological lability is maintained by a constant balance between the phenomena of formation and resorption, ensuring the renewal of bone structures. This bone remodeling accomplishes three main functions:
First of all, it allows the body to regulate the mineral balance (calcium and phosphate homeostasis).
-It then constitutes a mechanism for adapting the skeleton to its mechanical environment, thus reducing the risk of fracture.
-Finally, it allows tissue renewal and repair of bone damage created during stress.
Reminder on the organization and physiology of bone tissue
- Post-extraction anatomical variations
It combines osteoclastic resorption of the alveolar bone with bone apposition in the extraction socket. Resorption is very active during the first months of alveolar healing (3 to 6 months), then continues for up to a year after extraction, it occurs in the horizontal and vertical directions. It mainly affects the alveolar portion of the bone.
Some modifications should be carefully considered as to their impact on surgical technique or implant length (Schroeder et al, 1996). Generally speaking:
At the mandibular level, anterior crestal resorption is 4 times faster than that of the maxilla. In addition, resorption is faster in the lingual region (centrifugal resorption); the crest thus progressively loses its mesio-distal height and width. Vertical resorption of the mandible brings the mandibular canal closer to the crestal rim .
At the maxillary level, resorption in the vertical direction is associated with a more significant resorption in the vestibular direction (centripetal resorption movement). It often limits the bone volume available under the maxillary sinuses. The tuberosity and pterygomaxillary regions undergo less significant bone resorption than the other parts of the maxilla.
Reminder on the organization and physiology of bone tissue
Sensitive teeth react to hot, cold or sweet.
Sensitive teeth react to hot, cold or sweet.
Ceramic crowns perfectly imitate the appearance of natural teeth.
Regular dental care reduces the risk of serious problems.
Impacted teeth can cause pain and require intervention.
Antiseptic mouthwashes help reduce plaque.
Fractured teeth can be repaired with modern techniques.
A balanced diet promotes healthy teeth and gums.