If we utilize the tip back bend for the correction of a deep bite, it can clearly be seen that when the short segment of the bend is inserted in the molar tube, the large segment directs itself to the apical portion of the anterior zone(before being inserted in the slots of the braces of the incisors). This way we know that an intrusive force will be produced on the anterior zone and an extrusive force in the posterior zone. Another consideration that we have to mind with the placement of bends is that the short segment of the arch wire is going to represent the anchorage side, and the long segment of wire the side of no anchorage, this is due to the fact that Moment at the molar level (short part of the bend) is greater than the one that is being produced at the incisor level, making the molar much more resistant to movement.
The third law of Newton applies in almost all orthodontic movements; the law of Action and Reaction, which states that to every action there is always opposing and equal reaction. Sometimes the reaction to a movement results in an unwanted movement.
Dental movement can be classified in many ways:
1. Inclination:
a. Uncontrolcd inclination.
b. Controlled inclination,
2. Translation.
3. Root displacement.
4. Rotation
Dental movement is produced as a result of a biological response to the physiologic reaction toward forces applied by our mechanical procedures. So when we design our appliances it is very important to evaluate the forces that they will generate during treatment.
The center of resistance is the point a force has to pass through in order to move an object freely in a linear manner. Said in another way, every free body has a point known as mass center, therefore, every time that the line of action of a force passes through de mass center of a free body will suffer a translation movement.
Force is an action exerted by a body (wire, coil, elastic, etc.) over another body (teeth or bone), It expresses itself as mass times acceleration (mass x acceleration) and is a vector that presents;
Implantology has modified treatment planning dramatically in odontology. However, the operating microscope and its new armamentarium in endodontics have so broadened what can be treated, both surgically and non-surgically, with success and predictability that a comparison with studies done before the microscope's introduction is difficult. Rotary NiTi files have standarized the cleaning and shaping of canals, reduced the ledges, blocks, zips, tear-drops and perforations, and increased the success rate of endodontic treatments and retreatments.
When the alveolus has a defect that needs to be regenerated, graft materials should be used for this. Hard tissue grafts maintain the long-term soft tissue architecture and esthetics, and soft tissue coverage is necessary for hard tissue grafts to heal.
The implant must have initial stability. Vertically, a minimum of 4 mm of bone in the apical part of the alveolus is necessary to get implant stability. Class I or II bone quality (anterior mandible) is better than class III or IV (posterior maxilla). Laterally, if there is not enough bone envelope around, look for longer (bicorticalization) and, if possible, wider self-tapping or taper implants.
Radiography is critical to determine several things.
- Bone quality and quantity (height and width) allows the surgeon to determine how much bone is available in the proposed implant site. Good bone quality and quantity are necessary for immediate implant therapy success.
- Determining the long axis of the alveolar bone allows the surgeon to optimize the trajectory of implant placement with the emergence profile and loading characteristics of the implant.
- It helps to identify and localize important internal landmarks and anticipate and prevent surgical accidents: mandibular canal, maxillary sinus, nasal fossa, mental foramen, incisive canal, etc.
- The jaw shape and size, and jaw boundaries (including fossae), constitute the limits of the operation.
- Pathology such as retained roots tips, inflammatory processes, cysts and tumors can be detected.