international magazine of oral implantology

I research _ implant geometries Fig. 1_Overview of some available commercial short and mini implants. Fig. 2_Loading direction of the nu- merical models. A mini implant (2.5 x 15 mm) inserted in an idealised bone block with a cortical thickness of 1.2 mm (left) and a short implant (5.5 x 7 mm) inserted in an idealised bone block with a cortical thickness of 0.5 mm (right). _Abstract Shortandminidentalimplantshavebeenwidely used as treatment alternatives in certain selected clinical situations. However, a profound scientific analysis of the mechanical and biomechanical im- pact of the reduced length and diameter of these implant geometries has not been published until now.Usingfiniteelementanalysis,aseriesofdiffer- ent experimentally designed short and mini im- plants have been analysed with regard to their load transfer to the alveolar bone and have been com- pared to respective standard commercial implants. Mini implants have been inserted in an idealised bone bed representing the anterior mandibular jaw region and loaded with a force of 150 N. An imme- diate loading condition was assumed and analysed using the contact analysis option of the FE package MSC.Marc/Mentat. Short implants were inserted in an idealised posterior bone segment and loaded in osseointegrated state with forces of 300 N. Clearly increased bone loading was observed for the short and mini dental implants compared with standard implants,clearlyexceedingthephysiologicallimitof 100MPa.Thedeterminedbiomechanicalcharacter- isticscouldexplaintheslightlyincreasedfailurerate of short and mini dental implants. _Introduction The loss of crestal bone around dental implants hasbeenreportedtobeinfluencedbymanyfactors. These include surgical trauma, implant abutment microgap, bacterial infection of peri-implant tis- sues and biomechanical factors related to loading. Factors that affect the load transfer at the bone im- plant interface include the type of loading, material properties of the implant and prosthesis, implant geometry,surfacestructure,qualityandquantityof the surrounding bone, and nature of the bone-im- plant interface.9 There are many dental implant de- signsavailableonthemarketforspecificclinicalap- plications: standard implants, short implants with wide diameter and implants with small diameters. Allareavailableindifferentgeometries,threadcon- figurations (if any) and thread depth (Fig. 1). After tooth loss, however, severely atrophic residual alveolar ridges are fairly common, espe- cially in patients who have been edentulous for a long period of time. Posterior areas of the maxilla and the mandible are areas where clinicians have greater anatomical limitations. Reduced alveolar bone height very often represents a contraindica- tion to implant therapy, unless a procedure such as ridge augmentation or sinus floor elevation is per- formed. Although widely utilised, these techniques implygreatermorbidity,longertreatmenttimesand higher costs. The sinus cavity in the maxilla and alveolarnerveproximityinthemandibleareclinical situations where short implants could be consid- ered as an alternative treatment option. Numerous Biomechanical finite element analysis of small diameter and short dental implant Authors_Istabrak Hasan1 , Dr Friedhelm Heinemann2 , Maria Aitlahrach1 and Prof Dr Christoph Bourauel1 06 I implants1_2011 Fig. 1 Fig. 2