The objective was to analyze bone resorption patterns in posterior mandibles and the dimensions of their corresponding digital bone grafts. This could allow the fabrication of bone grafts with standardized dimensions that can be applied in the majority of clinical cases. Cone beam computed tomography scans (n = 120) were analyzed to evaluate the frequency of Cawood and Howell (C&H) classes. The most frequent class needing bone augmentation was virtually regenerated using specific software. Dimensions of the grafts were calculated. Class V was the most frequent atrophic class needing augmentation in posterior mandibles (20.4%). Severe atrophic stages were more frequent in females (adjusted P value = 0.001), in older people (adjusted P value = 0.31) and in the right mandible (adjusted P value = 0.03). After virtual regeneration of Class V cases (n = 36), 3 clusters based on the number of missing teeth were evident. The mean length of the grafts was 20 mm when 2 teeth were missing (reference), 23.9 mm in the case of 3 missing teeth (P < 0.001) and 29.6 mm for 4 missing teeth (P < 0.001). Height and width were comparable across the 3 clusters (P-values = 0.39–0.93). The mean graft volume was 1,469 mm3 in the case of 2 missing teeth (reference), 1,814 mm3 for 3 missing teeth (P = 0.001) and 2,177 mm3 for 4 missing teeth (P < 0.001). These volumes corresponded to those of soft-tissue expanders, suggesting the possibility of a 2-step augmentation protocol: soft-tissue expansion, followed by regeneration with prefabricated grafts of the corresponding volume. Class V was the most frequent resorption pattern requiring augmentation in posterior mandibles. Virtual regeneration revealed 3 clusters of grafts, differing only in length based on the number of missing teeth. A 2-step augmentation protocol is proposed using soft-tissue expanders and prefabricated grafts with corresponding volumes. This protocol might be more applicable in the right mandible, females and older patients.
KeywordsMandible; alveolar bone grafting; bone graft; cone beam computed tomography; soft-tissue expansion.
The following article describes 2 original techniques that use CAD/CAM technology to generate a pre-surgical healing abutment or provisional restoration. Two clinical cases are described using different techniques to create a guided soft-tissue emergence profile using a pre-surgical custom healing abutment or provisional restoration and their benefits. The first case describes the use of digital libraries with pontic emergence profiles. The 3-D object (tooth) is manipulated to replicate or to establish a natural contour that will determine the shape of the soft tissue during the healing process. The second technique describes the use of segmentation and mirroring of a natural tooth to generate an exact replica and emergence profile of the patient’s dentition. These techniques constitute a very simple and efficient way of generating a pre-surgical customized healing abutment or provisional restoration that allows the clinician to guide the soft-tissue healing process and emergence profile immediately after the surgery. The techniques are developed not to be software-specific, but rather to be used with any free or paid open architecture software.
KeywordsCAD/CAM; guided surgery; 3-D printing; segmentation; digital wax-up.
The objective of this article is to assess the clinical, radiographic and patient-related outcomes of patients with severe atrophy of the maxilla (Cawood and Howell Class V) rehabilitated with fixed full-arch prostheses on dental implants placed in anatomical buttresses and remnant bone. An observational retrospective clinical study was performed with a minimum follow-up period of 10 years. An analysis of the following parameters was performed: (a) periimplant parameters (plaque index, modified gingival index, probing pocket depth and keratinized mucosa width); (b) marginal bone loss; (c) implant survival rate; and (d) patient satisfaction based on a visual analog scale (VAS). Ten patients and 71 dental implants were studied, with a mean follow-up period of 126 months (range: 120–144). The mean plaque index was 1.0 ± 0.5, with a mean probing pocket depth of 2.3 mm (range: 1.0–4.0 mm). Sixty-one percent and 39% of the implants presented a modified gingival index of 1 and 2, respectively, and the mean keratinized mucosa width was 5.8 mm (range: 4.0–10.0 mm). The mean marginal bone loss of the implants was 0.7 ± 0.4 mm (range: 0.0–5.0 mm). The implant survival rate was 97.2%, and the overall mean patient satisfaction score was 90 (range: 0–100). Prosthesis cleaning ease scored lowest on the VAS. In our limited sample of patients with severe maxillary atrophy (Cawood and Howell Class V), the placement of dental implants in anatomical buttresses and remnant bone, associated with rehabilitation with fixed full-arch prostheses, was found to be an adequate treatment option in the long term regarding implant survival, marginal bone loss, periimplant clinical parameters and patient satisfaction.
KeywordsDental implants; atrophic maxilla; fixed prosthesis; full arch; long-term; graftless.