Bone modelling at fresh extraction sockets: immediate implant placement versus spontaneous healing. An experimental study in the beagle dog Vignoletti F, Discepoli N, Mu¨ller A, de Sanctis M, Mun˜oz F, Sanz M. Bone modelling at fresh extraction sockets: immediate implant placement versus spontaneous healing. An experimental study in the beagle dog. J Clin Periodontol 2012; 39: 91–97. doi: 10.1111/j.1600-051X.2011.01803.x. Abstract Objectives: The purpose of this investigation is to describe histologically the undisturbed healing of fresh extraction sockets when compared to immediate implant placement. Methods: In eight beagle dogs, after extraction of the 3P3 and 4P4, implants were inserted into the distal sockets of the premolars, while the mesial sockets were left to heal spontaneously. Each animal provided four socket sites (control) and four implant sites (test). After 6 weeks, animals were sacrificed and tissue blocks were dissected, prepared for ground sectioning. Results: The relative vertical buccal bone resorption in relation to the lingual bone was similar in both test and control groups. At immediate implant sites, however, the absolute buccal bone loss observed was 2.32 (SD 0.36) mm, what may indicate that while an apical shift of both the buccal and lingual bone crest occurred at the implant sites, this may not happen in naturally healing sockets. Conclusions: The results from this investigation showed that after tooth extrac- tion the buccal socket wall underwent bone resorption at both test and control sites. This resorption appeared to be more pronounced at the implant sites, although the limitations of the histological evaluation method utilized preclude a definite conclusion. Fabio Vignoletti 1 , Nicola Discepoli 1 , Anna Mu¨ ller 2 , Massimo de Sanctis 2 , Fernando Mun˜ oz 3 and Mariano Sanz 1 1 Graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Madrid, Spain; 2 Dipartimento di Scienze Odontostomatologiche, Universita` degli studi di Siena, Siena, Italy; 3 School of Veterinary, University of Santiago de Compostela, Santiago de Compostela, Spain Key words: beagle dog; bone resorption; fresh extraction socket; healing; immediate implant Accepted for publication 30 August 2011 In recent years, immediate implant placement after tooth extraction (Type 1 implant placement protocol; Hammerle et al. 2004) has become a common surgical protocol in daily practice. The advocates for this pro- cedure have argued that by reducing the surgical exposure, a more limited physiological bone resorption will occur after tooth extraction and implant installation (Paolantonio et al. 2001). The histological studies, both in humans (Wilson et al. 1998) and in animals (Anneroth et al. Conflict of interest and source of funding statement The authors declare that they have no conflict of interests. This study was supported by a research grant from Thommen Medical. © 2011 John Wiley & Sons A/S 91 J Clin Periodontol 2012; 39: 91–97 doi: 10.1111/j.1600-051X.2011.01803.x