Aim: To radiographically evaluate the effect of immediate implant placement plus alveolar ridge preservation (ARP) with a deproteneized bovine bone mineral and a collagen matrix (IMPL/DBBM/CM) as compared to ARP (DBBM/CM) or spontaneous healing (SH) on vertical and horizontal bone dimensional changes after 4 months of healing. Materials and methods: Thirty patients requiring extraction of one single-rooted tooth or premolar were randomly assigned to IMPL/DBBM/CM, ARP DBBM/CM or SH. Cone-beam computed tomography (CBCT) scans, performed before tooth extraction and after 4 months, were superimposed in order to assess changes in ridge height at the buccal and lingual aspect and in ridge width at 1 mm, 3 mm and 5 mm apical to the bone crest. Kruskal-Wallis test was applied for comparison of differences between groups. Results:No statistically significant differences between the groups were observed for the vertical bone resorption of the buccal and the lingual side, while significant differences were found between SH group (−3.37 ± 1.55 mm; −43.2 ± 25.1%) and both DBBM/CM (−1.56 ± 0.76 mm; −19.2 ± 9.1%) and IMPL/DBBM/CM (−1.29 ± 0.38 mm; −14.9 ± 4.9%) groups in the horizontal dimension at the most coronal aspect. Conclusion:Ridge preservation techniques using DBBM and CM reduce the horizontal bone morphological changes that occur, mostly in the coronal portion of the buccal bone plate following tooth extraction, when compared to spontaneous healing. This is true regardless of whether immediate implant placement is performed or not. K E Y W O R D S alveolar ridge preservation, CBCT, immediate implant placement, radiographic changes, tooth extraction | 777 CLEMENTINI ET aL.

Aim: To compare soft tissue dimensional changes and relative differences in soft and hard tissue volumes 4 months after single-tooth extraction and three different treatment modalities: spontaneous healing (SH) and alveolar ridge preservation by means of a deproteinized bovine bone mineral and a collagen matrix, with (IMPL/DBBM/CM) or without (DBBM/CM) immediate implant placement. Materials and Methods: STL files from study casts obtained at baseline and after 4 months were matched to calculate buccal soft tissue linear and volumetric changes. DICOM files from CBCTs were superimposed to STL files allowing the evaluation of soft tissue thickness at baseline and 4 months. Results: Mean horizontal reduction accounted for 1.46 ± 0.20 (SH), 0.85 ± 0.38 (DBBM-CM) and 0.84 ± 0.30 IMPL/DBBM-CM, with no statistical differences. Soft tissue thickness had a significant mean increase of 0.95 for SH group, compared to a non-significant mean decrease for DBBM-CM (0.20) and IMPL/DBBM-CM groups (0.07). Conclusion: A preservation technique with DBBM-CM, with or without immediate implant placement, did not reduce the horizontal linear and volumetric changes at the buccal soft tissue profile significantly at 4 months after tooth extraction when compared to spontaneous healing. This is due to a significant increase in soft tissue thickness in spontaneously healing sites.

Background: Clinical research related to dimensional change after tooth extraction has mainly focused on the biology of bone, while the effect of soft tissue healing on bone modelling and dimensional changes in post-extraction sites have received little attention. Aim/Hypothesis: To compare soft tissue dimensional changes and relative differences in soft and hard tissue volumes 4 months after single tooth extraction and 3 different treatment modalities: spontaneous healing (SH), alveolar ridge preservation (DBBM/CM) and immediate implant placement (IMPL/DBBM/CM). Materials and Methods: 30 patients requiring single-rooted tooth extraction participated to the trial. After atraumatic tooth extraction, patients were randomly assigned to SH, DBBM/CM with a biomaterial and a collagen matrix seal and IMPL/DBBM/CM with a biomaterial in the gap and a collagen matrix seal. STL files from study casts obtained at baseline and after 4 months were matched to calculate buccal soft tissues linear and volumetric changes. DICOM file from CBCTs were superimposed to STL files allowing the evaluation of soft tissue thickness at baseline and 4 month. Results: No significant differences between groups were observed when analyzing baseline characteristics. All groups demonstrated at 4 months a horizontal reduction in the dimensions of the bucco-lingual tissue contours. Although a tendency towards less reduction was observed in DBBM/CM and IMPL/DBBM/CM group, no statistically significant differences were observed. A similar trend was observed at the buccal aspect, although a statistically significant change was observed at 5 mm, where SH group had significant more resorption (1.66 mm), if compared to DBBM-CM group (1.02 mm) and IMPL/DBBM/CM group (0.85 mm). Buccal volumetric reduction was observed after 4 months in all groups, with no significant differences between them. After 4 months of healing the soft tissue thickness at 3 mm under the most coronal soft tissue point demonstrated a significant mean increase (0.95 mm) for SH group, whereas DBBM/CM and IMPL/and DBBM/CM demonstrated a NO-significant change. Conclusions and Clinical Implications: Treatment modality may be considered less critical in terms of contour alterations on a soft tissue level, since no differences between the three treatment modalities were observed in linear and volumetric changes that occur at the buccal soft tissue profile after tooth extraction. Lack of difference may be due to a significant increase in soft tissue thickness in SH sites. This increase might improve flap manageability if bone augmentation procedures were to be required during implant placement

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