Digital planning and bone regenerative technologies: A narrative review.

OBJECTIVES: The aim of this narrative review was to explore the application of digital technologies (DT) for the simplification and improvement of bone augmentation procedures in advanced implant dentistry. MATERIAL AND METHODS: A search on electronic databases was performed to identify systematic reviews, meta-analyses, randomized and non-randomized controlled trials, prospective/retrospective case series, and case reports related to the application of DT in advanced implant dentistry. RESULTS: Seventy-nine articles were included. Potential fields of application of DT are the following: 1) the use of intra-oral scanners for the definition of soft tissue profile and the residual dentition; 2) the use of dental lab CAD (computer-aided design) software to create a digital wax-up replicating the ideal ridge and tooth morphology; 3) the matching of STL (Standard Triangulation Language) files with DICOM (DIgital COmmunication in Medicine) files from CBCTs with a dedicated software; 4) the production of stereolithographic 3D models reproducing the jaws and the bone defects; 5) the creation of surgical templates to guide implant placement and augmentation procedures; 6) the production of customized meshes for bone regeneration; and 7) the use of static or dynamic computer-aided implant placement. CONCLUSIONS: Results from this narrative review seem to demonstrate that the use of a partially or fully digital workflow can be successfully used also in advanced implant dentistry. However, the number of studies (in particular RCTs) focused on the use of a fully digital workflow in advanced implant dentistry is still limited and more studies are needed to properly evaluate the potentials of DT.

Indications for implant-supported rehabilitation of the posterior atrophic maxilla: A multidisciplinary consensus among experts in the field utilising the modified Delphi method.

PURPOSE: To establish consensus-driven guidelines that could support the clinical decision-making process for implant-supported rehabilitation of the posterior atrophic maxilla and ultimately improve long-term treatment outcomes and patient satisfaction. MATERIALS AND METHODS: A total of 33 participants were enrolled (18 active members of the Italian Academy of Osseointegration and 15 international experts). Based on the available evidence, the development group discussed and proposed an initial list of 20 statements, which were later evalu-ated by all participants. After the forms were completed, the responses were sent for blinded ana-lysis. In most cases, when a consensus was not reached, the statements were rephrased and sent to the participants for another round of evaluation. Three rounds were planned. RESULTS: After the first round of voting, participants came close to reaching a consensus on six statements, but no consensus was achieved for the other fourteen. Following this, nineteen statements were rephrased and sent to participants again for the second round of voting, after which a consensus was reached for six statements and almost reached for three statements, but no consensus was achieved for the other ten. All 13 statements upon which no consensus was reached were rephrased and included in the third round. After this round, a consensus was achieved for an additional nine statements and almost achieved for three statements, but no consensus was reached for the remaining statement. CONCLUSION: This Delphi consensus highlights the importance of accurate preoperative planning, taking into consideration the maxillomandibular relationship to meet the functional and aesthetic requirements of the final restoration. Emphasis is placed on the role played by the sinus bony walls and floor in providing essential elements for bone formation, and on evaluation of bucco-palatal sinus width for choosing between lateral and transcrestal sinus floor elevation. Tilted and trans-sinus implants are considered viable options, whereas caution is advised when placing pterygoid implants. Zygomatic implants are seen as a potential option in specific cases, such as for completely edentulous elderly or oncological patients, for whom conventional alternatives are unsuitable.

The "White Layer Approach": A Graftless Gingival Augmentation Technique following Vertical GBR with Occlusive Titanium Barriers.

Guided bone regeneration surgery always leads to a deformation of the soft tissues consequent to passivation of the flap. In this article, a graftless technique for the restoration of the vestibular depth and for the augmentation of adherent soft tissue, called the "white layer approach", is proposed after a vertical GBR procedure in posterior areas. Six patients (five males and one female) with vertical bone atrophy were enrolled in the study and underwent three-dimensional bone augmentation with titanium barriers. After 6 months, during the second-stage surgery, a 0.5 mm thick layer of white pseudo-periosteum was observed underneath the titanium barrier and over the newly formed bone. The buccal portion of the pseudo-periosteum was left intentionally exposed, in order to promote the spontaneous formation of new adherent gingiva and the restoration of the original depth of the fornix. The implant insertion was then planned 3 months after the WLA in a conventional procedure. The buccal adherent soft tissue height was measured from the crestal point to the most apical point, using a periodontal probe, before the barrier removal at 3 months after the white layer approach (WLA). In all patients, a gain in adherent soft tissue varying from 5 to 8 mm was observed; the average adherent soft tissue gain (ASTG) was 6.75 mm. The vertical bone height was measured by CT scans at baseline and before the implant placement, and showed an average vertical bone gain (AVBG) of 4.08 mm. Within the limitations of this study, vertical GBR with titanium occlusive barriers (OTB) associated with the white layer approach (WLA) may represent a simplified technique for hard and soft tissue augmentation in posterior areas, even without a free gingival graft.

Group 1 ITI Consensus Report: The role of bone dimensions and soft tissue augmentation procedures on the stability of clinical, radiographic, and patient-reported outcomes of implant treatment.

OBJECTIVES: The aims of Working Group 1 were to address the role (i) of the buccolingual bone dimensions after implant placement in healed alveolar ridge sites on the occurrence of biologic and aesthetic complications, and (ii) of soft tissue augmentation (STA) on the stability of clinical, radiographic, and patient-related outcomes of implant treatments. MATERIALS AND METHODS: Two systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, recommendations for future research, and reflections on patient perspectives were based on structured group discussions until consensus was reached among the entire group of experts. The statements were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Dimensional changes of the alveolar ridge occurred after implant placement in healed sites, and a reduction in buccal bone wall thickness (BBW) of 0.3 to 1.8 mm was observed. In healed sites with a BBW of <1.5 mm after implant placement, increased vertical bone loss, and less favorable clinical and radiographic outcomes were demonstrated. Implants with buccal dehiscence defects undergoing simultaneous guided bone regeneration, showed less vertical bone loss, and more favorable clinical and radiographic outcomes, compared to non-augmented dehiscence defects during initial healing. At healthy single implant sites, probing depths, bleeding and plaque scores, and interproximal bone levels evaluated at 1 year, remained stable for up to 5 years, with or without STA. When single implant sites were augmented with connective tissue grafts, either for soft tissue phenotype modification or buccal soft tissue dehiscence, stable levels of the soft tissue margin, and stable or even increased soft tissue thickness and/or width of keratinized mucosa could be observed from 1 to 5 years. In contrast, non-augmented sites were more prone to show apical migration of the soft tissue margin in the long-term. Favorable aesthetic and patient-reported outcomes after STA were documented to be stable from 1 to 5 years. CONCLUSIONS: It is concluded that dimensional changes of the alveolar ridge occur after implant placement in healed sites and that sites with a thin BBW after implant placement are prone to exhibit less favorable clinical and radiographic outcomes. In addition, it is concluded that STA can provide stable clinical, radiographic, aesthetic, and patient-reported outcomes in the medium and long-term.

Accuracy and Technical Predictability of Computer Guided Bone Harvesting from the Mandible: A Cone-Beam CT Analysis in 22 Consecutive Patients.

This study assesses the accuracy and technical predictability of a computer-guided procedure for harvesting bone from the external oblique ridge using a patient-specific cutting guide. Twenty-two patients needing bone augmentation for implant placement were subjected to mandibular osteotomy employing a case-specific stereolithographic surgical guide generated through computer aided design. Differences between planned and real cut planes were measured comparing pre- and post-operative Cone Beam Computed Tomography images of the donor site according to six validated angular and displacement indexes. Accuracy and technical predictability were assessed for 119 osteotomy planes over the study population. Three different guide fitting approaches were compared. An average root-mean-square discrepancy of 0.52 (0.30-0.97) mm was detected. The accuracy of apical and medial planes was higher than the mesial and distal planes due to occasional antero-posterior guide shift. Fitting the guide with an extra reference point on the closest tooth performed better than using only the bone surface, with two indexes significantly lower and less disperse. The study showed that the surgical plan was actualized with a 1 mm safety margin, allowing effective nerve preservation and reducing technical variability. When possible, surgical guide design should allow fitting on the closest tooth based on both radiological and/or intra-oral scan data.

The Multiple Pedicle Coronally Advanced Flap for Multiple Deep Miller Class II Recessions: A Case Report.

INTRODUCTION: In recent years, several methods have been described for the treatment of deep Miller Class II recessions. Most of these techniques concentrate on single recessions or one deep recession accompanied by just slight neighboring root denudations. A modified technique is presented for treating two or more deep recessions beyond the mucogingival margin combining a subepithelial connective tissue graft (SCTG), enamel matrix derivative, and a multiple pedicle coronally advanced flap. To the best of our knowledge, this is the first report to describe the treatment of multiple deep Miller Class II recessions exceeding beyond the mucogingival junction using a pedicled advanced flap. CASE PRESENTATION: A 29-year-old woman was referred to the periodontal practice of JT for the treatment of progressive deep Miller Class II recessions. The root coverage procedure was performed by a modified multiple pedicle flap combined with a connective tissue graft harvested from the palate and enamel matrix derivative. The case was followed up for 2 years. CONCLUSIONS: This modified technique of a multiple pedicled flap is a feasible and useful method for treating several deep neighboring recessions. Due to the improved incision techniques, scar tissue formation might be reduced not to interfere with the esthetic result.

The Vestibular Shifted Flap Design for Vertical Bone Augmentation in the Maxilla: Case Report and Technical Notes.

During bone augmentation procedures, primary wound healing determines the bone augmentation result. After a crestal incision in the maxilla, the palatal flap might not be an adequate length to correctly couple to the vestibular flap and to seal the wound with horizontal mattress and single sutures. Due to the histologic structure made of dense connective tissue, the palatal flap eversion is impossible, negatively impacting the wound seal and primary healing. This case report describes the effectiveness and efficacy of an incision design to improve palatal flap management during bone augmentation procedures in the maxilla. Indeed, palatal flap verticalization is achieved. The incision line is proportionally shifted on the vestibular side, based on the defect anatomy, to obtain a palatal flap length extending at least 4 mm coronal to the bone graft level prior to wound closure. The described approach simplifies the optimal adaptation of the inner faces of the palatal and vestibular flaps, reducing the risk of nonprimary wound healing.

Alveolar ridge augmentation using the shell technique with allogeneic and autogenous bone plates in a split-mouth design-A retrospective case report from five patients.

Atrophic alveolar ridges of five patients were augmented with allografts and autografts on opposite sites, followed by dental implantation. Both augmentation materials led to equivalent bone gains. Allografts did not compromise the clinical outcome.

Mandibular Canal Position in Posterior Mandible: Anatomical Study and Surgical Considerations in Relation to Bone Harvesting Procedures.

The aim of this study is to evaluate the anatomical characteristics of the posterior region of the mandible and their surgical relevance related to bone harvesting procedures. Fifty retromolar cone beam computed tomography scans were analyzed considering the donor site anatomies. For each site, linear measurements were taken of cross-sectional scans to record perpendicular distances between the mandibular canal (MC) and the vestibular and crestal bone walls. Data showed that the distance from the MC to the vestibular bone wall is lower in the ramus area than in the external oblique ridge area (< 2.00 mm in 26% of cases). However, the distance between the MC and the crestal bone wall is higher in the ramus area than in the external oblique ridge area. There is less bone thickness in the ramus area, and this could expose the inferior alveolar nerve to damage if osteotomies are performed with fewer depth limitations, as reported in the literature.

Assessing the accuracy of computer-planned osteotomy guided by stereolithographic template: A methodological framework applied to the mandibular bone harvesting.

Intraoral autologous bone grafting represents a preferential choice for alveolar reconstruction prior to dental implant placement. Bone block harvesting guided by a computer-planned lithographic template is a novel and promising technique for optimizing the volume of harvested material, while controlling the osteotomy 3D position with respect to delicate anatomical structures. We provide a quantitative framework to non-invasively estimate the accuracy of this technique. In the proposed framework, the planned osteotomy geometry was compared to the real outcome of the procedure, obtained by segmentation of post-procedural cone beam computed tomography data. The comparison required the rigid registration between pre and post-procedural mandibular models, which was automatically accomplished by minimizing the sum of squared distances via a stochastic multi-trial iterative closest point algorithm. Bone harvesting accuracy was quantified by calculating a set of angular and displacement errors between the planned and real planes which characterized the excision block. The application of the framework to four cases showed its capability to quantify the tolerance associated with computer-guided bone harvesting techniques with submillimetric accuracy (<0.4 mm), within the limits of native image resolution. The validation methodology proved suitable for defining the safety margins of osteotomy surgical planning.

Vertical 3D Bone Reconstruction with Simultaneous Implantation: A Case Series Report.

Tooth loss generally leads to a corresponding loss of supporting bone structures, jeopardizing correct implant placement. Bone augmentation procedures facilitate reconstruction of the alveolar contours but lengthen treatment time by about 4 to 9 months. The aim of this case series report is to describe the short-term results of the combination of three-dimensional bone augmentation using the shell technique in conjunction with simultaneous implantation. A total of 10 patients who underwent autologous bone augmentation using the shell technique with simultaneous implantation were retrospectively examined. The shell technique is an augmentation procedure using thin cortical bone plates adapted to the buccal and oral walls of the defect to rebuild the contours of the alveolar ridge. The remaining spaces are filled with bone chips. Healing time before second stage surgery was 4 months. The vertical bone defect at the beginning (VD), the height of the vertical bone graft, resorption at the time of second-stage surgery (BR1) and 1 year after prosthetic rehabilitation (BR2), the total resorption between augmentation and 1 year (BRtot), and the vertical bone loss of the implant (VBL) were measured. VD was 3.1 mm. Values for BR1 and BR2 were 0.4 and 0.45 mm, respectively, resulting in a total bone loss of 0.85 mm of bone loss (BRtot). VBL was 0.45 mm 1 year after prosthetic rehabilitation. The simultaneous approach of vertical bone augmentation in the shell technique and implantation shows excellent results in bone reconstruction and stability up to 1 year after prosthetic reconstruction and can shorten treatment time by 4 to 9 months.

Results of Computer-Guided Bone Block Harvesting from the Mandible: A Case Series.

Autogenous bone harvesting is a well-documented surgical procedure. Autogenous mandibular bone harvesting carries a risk of anatomical structural damage because the surgeon has no three-dimensional (3D) control of the osteotomy planes. The aim of this case series was to describe the results of mandibular bone block harvesting applying computer-guided surgery. A sample of 13 partially dentate patients presenting bone deficiencies in the horizontal and/or vertical plane were selected for autogenous mandibular bone block graft. The bone block dimension was planned through a computer-aided design (CAD) process, defining ideal bone osteotomy planes to avoid damage to anatomical structures (nerves, teeth roots, etc) and to generate a surgical guide that imposed the 3D working direction to the bone-cutting instrument. The bone block dimension was always related to the defect dimension to be compensated. A total of 13 mandibular bone blocks were harvested to treat 16 alveolar defects (9 vertical and 7 horizontal). The mean planned mesiodistal dimension of the bone block was 24.8 ± 7.3 mm, the mean height was 8 ± 1 mm, and the mean thickness was 4 ± 2 mm. None of the treated patients experienced neurologic alteration of their alveolar nerve function. The preliminary data from this case series suggested that computer-guided bone harvesting could be a concrete opportunity for clinicians to obtain an appropriate volume of autogenous bone in a safe manner.

A computer-guided bone block harvesting procedure: a proof-of-principle case report and technical notes.

During autogenous mandibular bone harvesting, there is a risk of damage to anatomical structures, as the surgeon has no three-dimensional control of the osteotomy planes. The aim of this proof-of-principle case report is to describe a procedure for harvesting a mandibular bone block that applies a computer-guided surgery concept. A partially dentate patient who presented with two vertical defects (one in the maxilla and one in the mandible) was selected for an autogenous mandibular bone block graft. The bone block was planned using a computer-aided design process, with ideal bone osteotomy planes defined beforehand to prevent damage to anatomical structures (nerves, dental roots, etc) and to generate a surgical guide, which defined the working directions in three dimensions for the bone-cutting instrument. Bone block dimensions were planned so that both defects could be repaired. The projected bone block was 37.5 mm in length, 10 mm in height, and 5.7 mm in thickness, and it was grafted in two vertical bone augmentations: an 8 × 21-mm mandibular defect and a 6.5 × 18-mm defect in the maxilla. Supraimposition of the preoperative and postoperative computed tomographic images revealed a procedure accuracy of 0.25 mm. This computer-guided bone harvesting technique enables clinicians to obtain sufficient autogenous bone to manage multiple defects safely.

The role played by a suspended external-internal suture in reducing marginal flap tension after bone reconstruction: a clinical prospective cohort study in the maxilla.

PURPOSE: To define the role played by a suspended external-internal (SEI) suture in reducing marginal flap tension after bone augmentation in the maxilla and in enhancing primary wound healing. MATERIALS AND METHODS: Twenty partially edentulous patients requiring bone augmentation (either guided bone regeneration or autogenous bone block placement) before or simultaneous with implant insertion in the maxilla were enrolled in this clinical prospective cohort study. Flap tension was measured by a dynamometer, which was accurate to within 1 g. The force recorded was that needed to enable the vestibular extensible flap to reach the edge of the palatal nonextensible flap. Flap tension was recorded after the periosteum-releasing incision was made (before application of any suture; T1), and after the SEI suture was applied (T2). Final marginal flap adaptation was accomplished via horizontal mattress sutures and simple stitches. Wound healing was monitored at 1, 2, 4, and 16 weeks and classified as "obtained primary closure" or "compromised" as a result of dehiscence or marginal flap necrosis. RESULTS: The mean flap tension measured at T1 was 32.9 ± 7.7 g. After the SEI suture was applied, the mean marginal flap tension decreased to 4.1 ± 1.5 g. The marginal flap tension was reduced by 87.6% compared to the initial strain. All patients healed uneventfully, and no complications such as dehiscences or marginal flap necrosis were recorded. CONCLUSION: The application of the SEI suture reduced the tension on the margins of the flaps and played a decisive role in obtaining primary wound healing. In case of passive wound closure (strain < 5 g), the type of augmentation procedure (guided bone regeneration or autogenous block) was revealed to have no impact on the quality of wound healing.

Results of vertical bone augmentation with autogenous bone block grafts and the tunnel technique: a clinical prospective study of 10 consecutively treated patients.

The aim of this study was to report the outcome of the management of alveolar crest vertical defects using the tunnel technique approach associated with autogenous bone blocks prior to implant placement in 10 partially dentate consecutively treated patients. Four clinical linear measurements were taken: maximal extension of the vertical defect (VD) at the time of the augmentation procedure (time 0), vertical bone graft (VBG) recorded at time 0, bone resorption at implant placement (time 1), and bone resorption during implant healing at the time of abutment connection (time 2). All patients healed uneventfully, and no complications were recorded. Both mean VD and VBG at time 0 were 6.50 ± 1.43 mm. Mean bone resorption at time 1 was 0.30 ± 0.48 mm and mean bone resorption at time 2 was 0.25 ± 0.26 mm, yielding an overall vertical bone remodeling of 0.55 ± 0.49 mm (8.4%) after 8 months. This study supports the capability of a minimally invasive approach to regenerate bone in vertical defects prior to implant placement.

Changes in soft tissue dimensions following three different techniques of stage-two surgery: a case series report.

The aim of this case series report is to compare the results of the increase in keratinized mucosa using three different techniques of stage-two surgery. Thirty-two patients with one to eight dental implants who received prosthetic rehabilitation of the maxilla were included. Patients were divided into three groups based on preoperative anatomical considerations. Stage-two surgery was performed using either the apically repositioned flap (ARF; n = 14), the roll flap (RF; n = 10), or an apically repositioned flap combined with a connective tissue graft (ARFCT; n = 8). The height of the keratinized mucosa and relative tissue thickness were measured preoperatively and postoperatively at 2 weeks and 3, 6, and 12 months after surgery. The mean gains of keratinized mucosa and tissue thickness were calculated from these measurements. After 1 year, the mean gains in tissue thickness and keratinized tissue were 1.37 and 4.63 mm in the ARF group, 2.41 and 1.35 mm in the RF group, and 3.10 and 4.10 mm in the ARFCT group, respectively. There was no significant statistical difference between the 12-month and postoperative measurements (P > .05). In patients with deficient tissue thickness, a roll flap or an apically repositioned flap should be performed, while a lack of keratinized mucosa indicates the use of an apically repositioned flap with or without a connective tissue graft. When an increase in both keratinized mucosa and tissue thickness is necessary, an apically repositioned flap combined with a free connective tissue graft can be recommended. After a 12-month healing period, the obtained results showed excellent stability.

A new approach to maintenance of regenerated autogenous bone volume: delayed relining with xenograft and resorbable membrane.

PURPOSE: The aim of this case series is to propose an approach to help maintain autogenous bone grafts. This is done by applying a collagen membrane (CM) and anorganic bovine bone (ABBM) at the time of implant surgery, rather than at the time of ridge augmentation, to avoid volume loss after implants are inserted. MATERIALS AND METHODS: Ten patients with severe horizontal bone atrophy were consecutively enrolled in this study. A staged approach was chosen for implant placement following horizontal ridge augmentation. A block graft was harvested from the retromolar area and secured to the recipient site with fixation screws; contour overbuilding was avoided. The width of the ridge was measured before and after horizontal augmentation. After 4 months of healing, implants were inserted, the augmented site was relined with ABBM, and CM was applied to prevent bone volume loss. Another 4 months later, at the time of abutment placement, cone beam computed tomography was performed to quantify the end result. RESULTS: The mean horizontal ridge width prior to treatment was 2.1 ± 0.5 mm. Mean postsurgical crest width was 6.9 ± 0.5 mm. After the 4-month healing period, the mean alveolar crest width was 6.6 ± 0.6 mm. At the time of abutment connection, the mean width of the regenerated ridge, as measured on three-dimensional cone beam images, was 7.7 ± 0.8 mm. CONCLUSIONS: Minimal bone loss occurred in unprotected autogenous bone grafts with respect to alveolar bone contour (0.25 ± 0.29 mm). After the implants were inserted, no further remodeling/resorption occurred with sites treated by ABBM and CM relining; moreover, an additional increase in alveolar crest width was evident. The nonresorbable ABBM osseointegrated clinically and radiologically, preventing bone loss prior to implant loading. This layer appeared to maintain the regenerated crest volume.