Ranieri Martuscelli

Volume Changes of Grafted Autogenous Bone in Sinus Augmentation Procedure

PURPOSE To evaluate associations between the osseous remodeling and the 3-dimensional features of both the grafted bone and the recipient site, as well as the density of the grafted bone, and to assess the relation between the degree of bone resorption and the type of autogenous bone-grafting procedure or the source (block or particulate bone from iliac crest or block bone from chin). PATIENTS AND METHODS A retrospective chart review of patients receiving sinus lifting and grafting procedures for implant positioning was conducted: radiographic analysis of the volume and area of both sinuses and autogenous bone grafts was performed, as per Smolka et al and Krennmair et al. The volumetric remodeling--measured at 1 year after implant positioning as the percentage of residual bone (%R)--was correlated, with Spearman analysis, to 3-dimensional features of both graft and recipient sites. All quantities correlated with %R at a statistically significant level were used for 2-dimensional and multidimensional visualizations with scattergrams. RESULTS Twenty-five iliac crest or chin grafts were inlay positioned in the maxillary sinuses of patients. Computed tomography scans, taken before implant positioning and after 1 year, showed a 1-year negligible volume remodeling for block graft from chin (97.9%) but slightly greater resorption values (%R) for particulate and block grafts from iliac crest (93.8% and 83.3%, respectively). Three- and four-dimensional scattergrams of significant data resulting from Spearman correlation tests (particulate and block grafts both from iliac crest) showed a variation of the remodeling pattern dependent on 3-dimensional features, namely inlay graft thickness, surface area of the graft in contact with basal bone, volume of the recipient site, and surface area of the graft projecting into the sinus cavity. CONCLUSIONS Retrospective data analysis shows that iliac crest grafts positioned on a small basal bone volume (≤ 2.5 mL) may point to a very favorable remodeling of the volume when the particulate graft is molded to a thickness of less than 4 mm, with a reduced surface area protruding into the sinus (≤ 5 cm(2)). Bone blocks with a reduced contact surface and with basal bone (≤ 4 cm(2)) also display minimal resorption.

Healing of donor defect after mandibular parasymphyseal block harvesting: a 6-year computerized tomographic follow-up.

OBJECTIVES A long-term survey on the healing potential of large-sized parasymphyseal osseous defects. PATIENTS AND METHODS Ten patients, subjected to 14 bilateral and 3 unilateral parasymphyseal bone harvesting for alveolar ridge augmentation, were selected for the retrospective chart review. CT scans were performed immediately before bone grafting, before implant insertion, and then once annually for 6 years, and the volumes of the bone defects at the buccal aspect in the healing process were measured using a software program. Volumes from the yearly measurements were then compared statistically. RESULTS Volumes of both the intrasurgical defects, 0.77 (0.20) cc and of those in the one-year group, 0.60 (0.26) cc were statistically different from volumes of all the other time intervals (from 24 to 72 months) with all p-values less than 0.002 and 0.004, respectively. The healing of osseous defects in the long-term radiographic survey (6 years) resulted in bony infill of 63%. CONCLUSION For parasymphyseal defects of 0.7 cc, a maximum possible healing of two-thirds can be expected; a re-harvesting procedure could be performed 24 months after early surgery, due to both the formation of a new buccal cortical plate and the achievement of a steady state of osseous remodelling.

Five-year outcome of bone remodelling around implants in the maxillary sinus: assessment of differences between implants placed in autogenous inlay bone blocks and in ungrafted maxilla.

The placement of implants in the posterior maxillary area is considered a reliable procedure, offering recognized rehabilitative advantages. The aim of this study was to evaluate the performance of dental implants placed in the sinus floor augmented with a block autograft by comparing the outcomes over 5 years with those of dental implants positioned in non-augmented bone. This retrospective cohort study included 16 patients who had undergone prosthetic rehabilitation supported by dental implants between 2000 and 2006. One implant per patient was included and assigned to one of two predictor groups: grafted versus ungrafted maxillary sinus. Changes in marginal bone level (MBL) and apical bone level (ABL) over time, at 1, 3, and 5 years, were the primary outcome variables. Appropriate pair-wise comparison tests were performed. No significant differences were seen with regard to ABLs and among times between the grafted group (nine implants) and the ungrafted group (seven implants). Significant marginal bone resorption was found over time, primarily at the buccal aspect, in both study groups. The bone surrounding the apex of dental implants appeared stable after sinus augmentation in the grafted area. The behaviour of the two groups with regard to loss of MBLs over time was very similar.

Implant angulation: 2-year retrospective analysis on the influence of dental implant angle insertion on marginal bone resorption in maxillary and mandibular osseous onlay grafts.

ObjectivesThe purpose of this study was to determine the existence of correlations between marginal peri-implant linear bone loss and the angulation of implants in maxillary and mandibular augmented areas over the course of a 2-year survey.Materials and methodsDependent variables described the sample of the present retrospective chart review. By using three-dimensional radiographs, input variables, describing the implant angulation (buccal–lingual angle [φ] and mesial–distal angle [θ]) were measured; outcome variables described survival rate and marginal bone resorption (MBR) around dental implants in autogenous grafts (10 maxillae and 14 mandibles). Pairwise comparisons and linear correlation coefficient were computed.ResultsThe peri-implant MBR in maxillary buccal and palatal areas appeared less intensive in the presence of an increased angulation of an implant towards the palatal side. Minor MBR was recorded around mandibular dental implants positioned at a right angle and slightly angulated towards the mesial.ConclusionsResorption in buccal areas may be less intensive as the angulation of placed implants increases towards the palatal area in the maxilla, whereas for the mandible, a greater inclination towards the lingual area could be negative. In the mandibular group, when the implant was slightly angulated in the direction of the distal area, bone resorption seemed to be more marked in the buccal area.Clinical relevanceIn the planning of dental implant placement in reconstructed alveolar bone with autograft, the extremely unfavourable resorption at the buccal aspect should be considered; this marginal bone loss seemed to be very sensitive to the angulation of the dental implant.

A 5-Year Implant Follow-Up in Maxillary and Mandibular Horizontal Osseous Onlay Grafts and Native Bone

The purpose of this study is to analyze marginal bone levels (MBLs) around dental implants positioned in the upper and lower jaw with or without horizontal onlay grafting procedures, and to survey implant survival with a follow-up of 5 years. Seventeen patients were surveyed in the present retrospective chart review. A total of 27 dental implants positioned in pristine bone and 21 in horizontally grafted bone were enrolled. MBLs were recorded for 4 aspects during a radiologic survey of 5 years. Significant differences were searched for among times and surgical procedures with paired and unpaired comparison tests, respectively, and survival rates were calculated for the 2 groups. In the maxilla, no statistically-significant differences between pristine and augmented groups were obtained; the time comparisons for pristine implants showed an affection of palatal, mesial, and distal sides, whereas the resorption around implants placed into horizontally grafted bone of anterior maxilla seemed to be limited just to buccal and distal aspects. Comparisons with the pristine horizontal procedure revealed that just the buccal sides were involved. The analysis of time comparisons attested to a continuous alveolar bone remodeling during the entire time of the survey for the pristine group. Given the extremely unfavorable resorption at the buccal aspect of the augmented areas, clinicians should reserve dental implant positioning into horizontal bone graft to selected patients, in whom it may represent one of the last opportunities of rehabilitation with a fixed prosthesis.

Histological and clinical survey of polylactic-polyglycolic acid and dextrane copolymer in maxillary sinus lift: A pilot in vivo study

Of various proposed alternatives to autogenous bone, a synthetic, degradable copolymer of PLA-GLA and dextrane seems to be a promising biomaterial for maxillary sinus lift. Consecutive partially edentulous patients showing severe monolateral posterior maxillary atrophy were treated via sinus lift using PLA-GLA-dextrane copolymer as the sole filler. Delayed implant positioning was performed and cores of regenerated tissues and native bone controls were retrieved and evaluated by light and electron microscopy, histomorphometry, microhardness and qualitative X-ray analysis. Seven sinuses in 7 patients were augmented with PLA-GLA-dextrane copolymer. Six to nine months after the copolymer ‘graft’, 17 bone cores were retrieved: all histological sections contained newly synthesized, mineralized material and new bone in various stages of development. Histomorphometry revealed average Trabecular Bone Volume (TBV) values ranging from 51% (6 months) to 77% (9 months). Backscattered scanning electron microscopy (BSE) in experimental and control samples confirmed histology findings. Microhardness values suggested newly formed bone at nine months was not as hard as native bone. Ca and P content was similar in 9-month regenerated and native bone. Seventeen implants were inserted in the second stage of surgery: resulting Implant Success (SR) and Cumulative Success (CSR) up to 3 years were 100% following Albrektssons criteria. Sinus lift augmentation using PLA-GLA-dextrane copolymer as the sole filler resulted in uneventful surgeries. New bone formation was evident histologically and its maturation was still in progress after 9 months. Successful, staged implant positioning was achieved in regenerated tissue.