Accuracy of flapless surgery using an autonomous robotic system in full-arch immediate implant restoration: A case series.

OBJECTIVES: This observational study aimed to evaluate the accuracy of robotic computer-assisted implant surgery (r-CAIS) for full-arch immediate restoration and to analyse possible factors contributing to deviations. METHODS: Three edentulous patients (five arches) underwent r-CAIS. Osteotomies were performed using an autonomous robot under the surgeon's supervision, and implant placement was performed in a freehand or robotic manner. Prefabricated provisional prostheses were delivered immediately after surgery. Postoperative cone beam computed tomography scans were performed to assess the deviations between the planned and placed implants. Statistics were compared with deviations of s-CAIS outlined in a meta-analysis. RESULTS: A sum of 28 implants were used. The mean global coronal and apical deviations measured 0.91 ± 0.43 mm and 1.01 ± 0.45 mm, respectively, and the mean angular deviation measured 1.21 ± 1.24 º. The r-CAIS showed significantly better precision than the s-CAIS in full-arch cases (P < 0.001). The implants inserted using the robotic arm exhibited fewer deviations than those placed in the freehand manner. Eighty percent of prefabricated provisional prostheses were successfully delivered. CONCLUSIONS: Within the limitations of the present study, our data suggest that autonomous r-CAIS is a feasible approach for simultaneous immediate restoration in edentulous patients, showing better accuracy than s-CAIS. Further large-scale studies are necessary to verify the advantages and disadvantages of this novel technique and to explore possible factors that influence its accuracy. CLINICAL SIGNIFICANCE: Autonomous r-CAIS can provide clinically acceptable implant placement accuracy in edentulous patients, significantly surpassing s-CAIS. This level of accuracy may represent a viable therapeutic approach for simultaneous immediate full-arch restoration.

Feasibility of implant placement in healed mandibular molar sites: A retrospective cone beam computed tomography study.

STATEMENT OF PROBLEM: Implant placement in the mandibular molar sites plays a crucial role in the restoration of edentulous mandibles. However, the evaluation of bone quantity before implant surgery using cone beam computed tomography (CBCT) is lacking. PURPOSE: The purpose of this clinical study was to evaluate CBCT images of edentulous patients to analyze the feasibility of implant placement in healed mandibular molar sites. MATERIAL AND METHODS: The CBCT data of 138 patients were analyzed in the sagittal plane for measurements of mandibular bone height (MBH), superior bone height (SBH), inferior bone height (IBH), buccal bone width (BBW), lingual bone width (LBW), and alveolar bone widths (ABWs). The edentulous sites were categorized according to the bone quantity and complexity of the implant surgery. Multivariate analysis of variance (MANOVA) was used to analyze the site, sex, and age-related variations. An independent t test was used to compare the difference of bone dimension in different sites and between sexes. One-way ANOVA followed by post hoc tests were used to analyze the difference between different age groups. Categorical variables were presented as number of events and percentages. The chi-squared test was used to compare categorical variables (α=.05). RESULTS: A total of 534 sites of interest were recorded, including 274 hemimandibles. A significant difference in BBW was found between the first and second molar sites. Men had higher MBH, SBH, IBH, and BBW than women. The distribution of implant surgical complexity in the conventional group was 63.5%, while the buccolingual tilted implant group accounted for 17.0%, and the complicated group accounted for 19.5%. Of the 274 hemimandibles, an implant could be placed directly at molar sites in 88% of situations. CONCLUSIONS: The BBW at the mandibular second molar site was greater than that at the first molar site. The amount of available bone in the SBH and BBW was greater in men than in women at the healed molar sites. Age did not significantly affect the complexity of the implant surgery. Implants can be placed directly in healed mandibular molar sites in most patients who require a complete arch mandibular implant-supported restoration.

The accuracy of dynamic computer assisted implant surgery in fully edentulous jaws: A retrospective case series.

OBJECTIVES: To evaluate the accuracy of implant placement using a dynamic navigation system in fully edentulous jaws and to analyze the influence of implant distribution on implant position accuracy. MATERIALS AND METHODS: Edentulous patients who received implant placement using a dynamic navigation system were included. Four to six mini screws were placed in the edentulous jaw under local anesthesia as fiducial markers. Then patients received CBCT scans. Virtual implant positions were designed in the planning software based on CBCT data. Under local anesthesia, implants were inserted under the guidance of the dynamic navigation system. CBCTs were taken following implant placement. The deviation between the actual and planned implant positions was measured by comparing the pre- and postsurgery CBCT. RESULTS: A total of 13 edentulous patients with 13 edentulous maxillae and 7 edentulous mandibles were included, and 108 implants were placed. The average linear deviations at the implant entry point and apex were 1.08 ± 0.52 mm and 1.15 ± 0.60 mm, respectively. The average angular deviation was 2.85 ± 1.20°. No significant difference was detected in linear and angular deviations between the maxillary and mandibular implants, neither between the anterior and posterior implants. CONCLUSIONS: The dynamic navigation system provides high accuracy for implant placement in fully edentulous jaws, while the distribution of the implants showed little impact on implant position accuracy.

Accuracy of dental implant surgery using dynamic navigation and robotic systems: An in vitro study.

OBJECTIVES: To compare the accuracy of dental implant placement using a dynamic navigation and a robotic system. METHODS: Eighty three-dimensional (3D) printed phantoms, including edentulous and partially edentulous jaws, were assigned to two groups: a dynamic navigation system (Beidou-SNS) group and a robotic system (Hybrid Robotic System for Dental Implant Surgery, HRS-DIS) group. The entry, exit and angle deviations of the implants in 3D world were measured after pre-operative plans and postoperative cone-beam computed tomography (CBCT) fusion. A linear mixed model with a random intercept was applied, and a p value <.05 was considered statistically significant. RESULTS: A total of 480 implants were placed in 80 phantoms. The comparison deviation of the dynamic navigation system and robotic system groups showed a mean (± SD) entry deviation of 0.96 ± 0.57 mm vs. 0.83 ± 0.55 mm (p=0.04), a mean exit deviation of 1.06 ± 0.59 mm vs. 0.91 ± 0.56 mm (p=0.04), and a mean angle deviation of 2.41± 1.42° vs. 1 ± 0.48° (p<0.00). CONCLUSIONS: The implant positioning accuracy of the robotic system was superior to that of the dynamic navigation system, suggesting that this prototype robotic system (HRS-DIS) could be a promising tool in dental implant surgery. CLINICAL SIGNIFICANCE: This in vitro study is of clinical interest because it preliminarily shows that a robotic system exhibits lower deviations of dental implants than a dynamic navigation system, in dental implant surgery, in both partially and completely edentulous jaws. Further clinical studies are needed to evaluate the current results.

Patient- and clinician-reported outcomes for the additively manufactured sub-periosteal jaw implant (AMSJI) in the maxilla: a prospective multicentre one-year follow-up study.

The clinical outcomes of maxillary rehabilitation with the additively manufactured sub-periosteal jaw implant (AMSJI; CADskills BV) were evaluated in edentulous patients with a Cawood-Howell atrophy classification ≥5 in all regions of the maxilla. Fifteen consecutive patients were included in the study and followed up for 1 year. They were interviewed using a survey protocol and were examined clinically and radiographically preoperatively (T0) and at 1 (T1), 6 (T2), and 12 (T3) months after permanent upper prosthesis placement. The patients reported an increased oral health-related quality of life. The overall mean Oral Health Impact Profile-14 score at T0 was 17.20 (standard deviation (SD) 6.42). When results at T0 were compared to those at T1 (mean 8.93, SD 5.30), a statistically significant difference was seen (P = 0.001). At T3, the mean value was 5.80 (SD 4.18). Compared to T0, there was also a statistically significant difference at T3 (P = 0.001). General satisfaction based on the numerical rating scale was a mean 49.93 at T1, which was less than patient expectation prior to treatment at T0 (52.13). A higher overall value was seen at T3 (53.20) when compared to T0. Within the constraints of the short follow-up, the AMSJI appears to be a promising tool for patients with extreme jaw atrophy. The high patient expectations were met without complications.

Combined bone- and mucosa-supported 3D-printed guide for sinus slot preparation and prosthetically driven zygomatic implant placement.

The use of zygomatic implants to rehabilitate the severely atrophic maxilla has been well documented since first being introduced by Brånemark. Placement of zygomatic implants is technically complex, with catastrophic complications and numerous prosthetic challenges resulting from imprecise placement. The purpose of this report was to demonstrate a technique that allows transfer of the preoperatively planned sinus slot position to the surgical field by using cone beam computed tomography (CBCT) and an implant planning software program to fabricate a combined bone- and mucosa-supported 3D-printed surgical guide. This facilitates optimal zygomatic implant positioning and promotes favorable biomechanics with a predictable prosthetic outcome.

Soft tissue-based registration of intraoral scan with cone beam computed tomography scan.

The aim of this study was to evaluate a novel soft tissue-based method to register an intraoral scan (IOS) with a cone beam computed tomography (CBCT) scan. IOS and CBCT data were obtained from eight dentate patients (mean age 21±2 years; three male, five female) and 14 fully edentulous patients (mean age 56±9 years; eight male, six female). An algorithm was developed to create a soft tissue model of the CBCT scan, which allowed a soft tissue-based registration to be performed with the IOS. First, validation was performed on dentate jaws with registration of the palatal mucosal surface and accuracy evaluation at the level of the teeth. Second, fully edentulous jaws were registered using both the palatal and alveolar crest mucosal surfaces. Distance maps were created to measure the method accuracy. The mean registration error was 0.49±0.26mm for the dentate jaws. Registration of the fully edentulous jaws had a mean error of 0.16±0.08mm at the palate and 0.16±0.05mm at the alveolar crest. In conclusion, the high accuracy of this registration method may allow the digital workflow to be optimized when no teeth are available to perform a regular registration procedure.

Accuracy Evaluation of the Computer-Designed Selective Laser Sintering Surgical Guide for Flapless Immediate Loading Dental Implants Surgery in Edentulous Jaws.

This study was designed to evaluate the accuracy of a novel computer-designed and selectively laser sintered surgical guide for flapless dental implant placement in the edentulous jaw. Fifty dental implants were placed in 11 patients with at least 1 totally edentulous jaw. Initially, cone-beam computed tomography (CBCT) was performed in each patient to define the virtual position of the dental implants based on the assessment of bone availability and the proposed dental prosthesis. After virtual planning, 3D surgical guides were printed using selective laser sintering. CBCT was repeated after the surgery, and the pre- and postoperative images were overlapped in computer-assisted design software to compare the planned and actual positions of the dental implants using a 1-sample t test. The mean ± angular standard deviation between the long axes of the planned and final dental implant positions was 4.58° ± 2.85°; the linear deviation in the coronal position was 0.87 ± 0.49 mm and in the apical region of the dental implants was 1.37 ± 0.69 mm. These differences were statistically significant (P < .001). The proposed modifications reduced the deviations, resulting in an improvement in the technique. We were able to place implants and temporary prostheses using the present protocol, taking into account the differences between the planned and final positions of the dental implants.

Rehabilitation of Atrophic Maxilla With Immediate Loading of Extrasinus Zygomatic Implant.

ABSTRACT: The aim of this case series was to evaluate the long-term success rate of immediate occlusal loading of extrasinus zygomatic dental implants after a 3-year follow-up. The sample consisted of 31 patients (mean age of 64 years) with atrophic maxillae rehabilitated with 1 to 4 extrasinus zygomatic implants, placed unilaterally or bilaterally. All the patients received complete implant-supported dental prostheses with immediate loading by associating zygomatic implants with conventional implants. None of the procedures were associated with bone grafts. During the 3-year period of follow-up in the present study, all the patients attended clinical sessions and underwent radiographic exams every 6 months. In total 55 zygomatic and 69 conventional implants were placed, where 1 zygomatic and 2 conventional implants were lost, representing success rates of 98.18% and 97.20%, respectively. None of the studied patients had signs of sinusitis or changes in the maxillary sinuses. All the patients showed occlusal contact on natural antagonist teeth or implant-supported dental prostheses. Therefore, it was concluded that the use of exteriorized zygomatic implants with immediate loading represented a feasible option with high success rates for the treatment of atrophic maxilla.

Fully Guided Zygomatic Implant Surgery.

INTRODUCTION: Rehabilitating a severely atrophic maxilla is a complex procedure. In case of severe resorption, zygomatic implants are indicated and loading of the implants at the end of the surgery is desirable. We present a new method by means of guided surgery for the placement of zygomatic implants, using specially designed metal templates that should be supported by bone. METHODS: The treatment planning for completely guided prosthetic rehabilitation of the maxilla with zygomatic implants was digitally performed. A radiographic template was designed for the prosthetic treatment planning. A surgical template was used to replicate the digitally planned steps in vivo. RESULTS: The procedure ended with the positioning of a custom-made temporary prosthesis. This method can reduce the surgery duration, simplify the procedure, and optimize the outcome. It requires equal cooperation among technicians, prosthodontists, and surgeons. Nineteen out of twenty patients included in the study presented successful implants and prosthesis at the moment of analysis. CONCLUSIONS: The present approach addressed the needs for zygomatic-implant surgery. The surgical and prosthetic plan, position, emergence, the shape of the implants, the position of the temporary prosthesis, the inter-arch relationships, and surgical templates were designed in a completely virtual environment and performed by the surgeon on stereolithographic models beforehand. Consequently, the surgical procedure was considerably simplified.

Accuracy of implant surgical guides fabricated using computer numerical control milling for edentulous jaws: a pilot clinical trial.

BACKGROUND: To evaluate the accuracy of a computer numerical control (CNC) milled surgical guide for implant placement in edentulous jaws. METHODS: Edentulous patients seeking implants treatment were recruited in this prospective cohort study. Radiographic guides with diagnostic templates were fabricated from wax-up dentures. Patients took cone-beam computed tomography (CBCT) wearing the radiopaque radiographic guides. Implant positions were virtually designed in the planning software based on the CBCT data, and the radiographic templates were converted into surgical guides using CNC milling technique. Forty-four implants were placed into 12 edentulous jaws following guided implant surgery protocol. Post-surgery CBCT scans were made for each jaw, and the deviations between the planned and actual implant positions were measured. Deviation of implant position was compared between maxilla and mandible, and between cases with and without anchor pins using independent t-test. RESULTS: Nine patients (3 males and 6 females) with 12 edentulous jaws were recruited. The mean age of patients was 59.2 ± 13.9 years old. All 44 implants was placed without complication and survived, the mean three dimensional linear deviation of implant position between virtual planning and actual placement was 1.53 ± 0.48 mm at the implant neck and 1.58 ± 0.49 mm at the apex. The angular deviation was 3.96 ± 3.05 degrees. No significant difference was found in the deviation of implant position between maxilla and mandible (P = 0.28 at neck, 0.08 at apex), nor between cases with and without anchor pins (P = 0.87 at neck, 0.06 at apex). CONCLUSIONS: The guides fabricated using the CNC milling technique provided comparable accuracy as those fabricated by Stereolithography. The displacement of the guides on edentulous arch might be the main contributing factor of deviation. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR-ONC-17014159 (July 26, 2017).

Comparison of the Accuracy of Image Registration Methods for Merging Optical Scan and Radiographic Data in Edentulous Jaws.

PURPOSE: The image registration of optical scans to radiographic images is essential for performing computer-guided implant surgery. This study aimed to evaluate the effect of different image matching conditions on the accuracy of image registration for computer-guided implant surgery in completely edentulous jaws. MATERIALS AND METHODS: The optical scan image of a completely edentulous study model was registered to the respective cone-beam computed tomography data using three different image matching conditions: small point (SP), large point (LP), and entire surface (ES). For the SP and LP groups, gutta-percha markers (1.0 and 3.0 mm in diameter) were attached to a base template, and a radiopaque impression material was relined on the intaglio surface of template in the ES group. Image registration was performed by 20 operators in the images obtained from each group at an interval of 2 weeks (n = 20 in each group), and the registration accuracy was assessed by calculating the aligned position of the edentulous arch image. One-way analysis of variance with Tukey post hoc tests was used to compare the results among the groups (α = 0.05). RESULTS: The mean registration error was significantly larger in the SP group (0.52 ± 0.19 mm) than in the LP group (0.29 ± 0.08 mm) and ES group (0.27 ±0.06 mm) (F = 24.689, p < 0.001). No difference was found between the LP and ES groups. The image matching discrepancy was more homogeneously distributed on the arch in the ES group than in the other groups. CONCLUSION: The accuracy of image registration is affected by the size of the congruent area shown in the optical scan and radiographic images. The entire surface-based matching method is more accurate as compared to the small point-based matching method in the image registration for implant planning in full edentulous jaws.

The reliability of surgeons to avoid traumatic insertion of dental implants into high-risk regions: a panoramic radiograph study.

BACKGROUND: The posterior regions of the jaws usually represent a significant risk for implant surgery. A non-valid assessment of the available bone height may lead to either perforation of the maxillary sinus floor or encroachment of the inferior alveolar nerve and consequently to implant failure. This study aimed to evaluate the reliability of surgeon's decision in appraising the appropriate implant length, in respect to vital anatomical structures, using panoramic radiographs. METHODS: Only implants that are inserted in relation to the maxillary sinus (MS) or the mandibular canal (MC) were enrolled (first premolars [1P], second premolars [2P], first molars [1M], and second molars [2M]). All preoperative panoramic radiographs were evaluated under standard conditions. The postoperative estimation (under/over) was determined depending on the available bone height (ABH) measured from the apical end of the implant to the floor of the MS and the roof of the MC using cone beam computed tomography (CBCT). Any complication or side effect that associated with overestimated implants insertion was recorded. RESULTS: The study sample included 73 patients (predominantly females) who had consecutively received 148 implants, of which 68 were inserted in the posterior maxilla and 80 in the posterior mandible. Underestimation was recorded in 93.2% of the measurements. The remaining bone height after implants insertion was < 2 mm in the majority of underestimated cases (73.9%); they were significantly (P < 0.01) more than sites with remaining bone ≥ 2 mm (26.1%). In the posterior mandible, overestimation was significantly higher than posterior maxilla. Five cases with transient paresthesia were reported in the mandibular overestimated implants. CONCLUSIONS: This study specified that surgeon's choice of implants length, based on panoramic radiographs, was reliable regarding the incapability to insert implants with further length in the majority of underestimated cases, the low percent of overestimated measurements, and the minor associated complications.

The lingual foramina, a potential risk in oral surgery. A retrospective analysis of location and anatomic variability.

OBJECTIVE: This study evaluates the mandibular lingual foramina (LF) using computed tomographic imaging data from a large Central European cohort, focusing on the most relevant anatomical parameters. We aimed to examine whether there are differences in key parameters between ethnic groups, or based on age and gender. Additionally, we analyze the potential effect of tooth loss on the LF and discuss risk management options before and during surgery. METHODS: 460 CT scans of adults (273 females and 186 males) were examined. The number, the location and the diameter of the median and lateral LF were assessed for each patient. The data was analyzed statistically, whereby a p-value lower than 0.05 was considered as significant. RESULTS: Median and lateral LF were present in 95,9%, and 38,9% of patients, respectively. Male patients had a greater number of LF than females. While the majority of median LF (62%) was located above the mental spine, the majority of lateral LF was located below (84%). The diameter of lateral LF (1,15 mm ± 0,33) was smaller than for median LF (1,22 mm ± 0,35), as well the lateral canals (4,8 mm ± 1,28) were shorter than the median canals (5,32 mm ± 1,74). Lateral LF were equidistant to the symphysis (13,89 ± 3,63 mm) on either side. Critical diameter size >1 mm was found in about 2/3 of our cases. The distance from the foramen to the residual ridge was ∼7 mm less in edentulous patients compared to dentulous patients. CONCLUSION: The median LF is a near-obligatory structure of the mandible, while the lateral LF is a frequently encountered structure. Age does not seem to affect the frequency of LF. Edentulous patients did not show differences regarding the presence of the LF, but their vertical osseous dimension was diminished by 7 mm and they may, therefore, be at an increased risk of adverse surgical incidents. The main findings of this study relate to the substantial variability in the anatomy and location of the LF and confirm with previous studies. As the LF can be reliably detected using CT/CBCT, the use of three-dimensional-imaging is recommended prior to conducting oral surgery. Careful pre-operative planning and accurate anatomical information may help to avoid surgical complications. To ascertain the potential significance of ethnicity on LF, more data need to be collected using standardized methodologies. A definitive conclusion on the impact of ethnicity on LF thus cannot currently be drawn based on the results of our study and those available from the published medical literature.

Factores sistémicos asociados con el edentulismo, según edad y género, mediante las radiografías panorámicas y expedientes digitales / Systemic factors associated with edentulism according to age and gender by panoramic radiographs and digital records

Resumen Esta investigación se realizó con el objetivo de determinar los principales factores sistémicos que provocan edentulismo en los pacientes que asisten a la Clínica de Odontología, con el fin de educar y concientizarlos sobre la relación entre la pérdida de piezas dentales y la salud en general, así como las causas y consecuencias del edentulismo. Para el estudio se tomó una muestra de 954 expedientes del último cuatrimestre de 2017. Estos registros se evaluaron para obtener un número de 108 pacientes edéntulos con factores sistémicos, total utilizado para este trabajo.

Abstract This research was carried out with the aim to determine the main systemic factors that cause edentulism in patients attending the Dental Clinic, in order to enhance patient education concerning the relationship between toothloss and with general health, as well as the causes and consequences of edentulism. For this study, a sample of 954 records was acquired from the last four months of the year 2017. These records were evaluated to obtain a number of 108 patients with systemic factors, the overall participants for this study.

Combining Intraoral and Face Scans for the Design and Fabrication of Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) Polyether-Ether-Ketone (PEEK) Implant-Supported Bars for Maxillary Overdentures.

PURPOSE: To present a digital method that combines intraoral and face scanning for the computer-assisted design/computer-assisted manufacturing (CAD/CAM) fabrication of implant-supported bars for maxillary overdentures. METHODS: Over a 2-year period, all patients presenting to a private dental clinic with a removable complete denture in the maxilla, seeking rehabilitation with implants, were considered for inclusion in this study. Inclusion criteria were fully edentulous maxilla, functional problems with the preexisting denture, opposing dentition, and sufficient bone volume to insert four implants. Exclusion criteria were age < 55 years, need for bone augmentation, uncompensated diabetes mellitus, immunocompromised status, radio- and/or chemotherapy, and previous treatment with oral and/or intravenous aminobisphosphonates. All patients were rehabilitated with a maxillary overdenture supported by a CAD/CAM polyether-ether-ketone (PEEK) implant-supported bar. The outcomes of the study were the passive fit/adaptation of the bar, the 1-year implant survival, and the success rates of the implant-supported overdentures. RESULTS: 15 patients (6 males, 9 females; mean age 68.8 ± 4.7 years) received 60 implants and were rehabilitated with a maxillary overdenture supported by a PEEK bar, designed and milled from an intraoral digital impression. The intraoral scans were integrated with face scans, in order to design each bar with all available patient data (soft tissues, prosthesis, implants, and face) in the correct spatial position. When testing the 3D-printed resin bar, 12 bars out of 15 (80%) had a perfect passive adaptation and fit; in contrast, 3 out of 15 (20%) did not have a sufficient passive fit or adaptation. No implants were lost, for a 1-year survival of 100% (60/60 surviving implants). However, some complications (two fixtures with peri-implantitis in the same patient and two repaired overdentures in two different patients) occurred. This determined a 1-year success rate of 80% for the implant-supported overdenture. CONCLUSIONS: In this study, the combination of intraoral and face scans allowed to successfully restore fully edentulous patients with maxillary overdentures supported by 4 implants and a CAD/CAM PEEK bar. Further studies are needed to confirm these outcomes.

Four-implant-supported fixed prosthesis and milled bar overdentures for rehabilitation of the edentulous mandible: A 1-year randomized controlled clinical and radiographic study.

PURPOSE: The purpose of this study was the clinical and radiographic evaluation of four-implant-supported fixed prostheses and milled bar overdentures for rehabilitation of the edentulous mandible. MATERIALS AND METHODS: Thirty-six edentulous participants received four implants in the mandible (two vertical implants in the canine/lateral incisor area and two distally inclined implants anterior to the mental foramina) using flapless surgery. The implants were loaded with the mandibular dentures in the same day after necessary modifications. Three months after implant placement, participants were randomly allocated to one of two groups: (1) the overdenture group, where participants received milled bar overdentures; or (2) the fixed group, where participants received ceramo-metal fixed prostheses. Plaque and gingival indices, pocket depth, implant stability (using Osstell device), and marginal bone resorption (using standardized intraoral radiographs) were evaluated at the time of prosthesis insertion (T0), and 6 (T6) and 12 (T12) months after insertion. RESULTS: The implant survival rate was 100% for both groups. Plaque Index, Gingival Index, pocket depth, implant stability, and bone resorption significantly increased by time for anterior (P < .001) and posterior (P < .018) implants. Fixed prostheses showed significantly higher Plaque Index, Gingival Index, and pocket depth than milled bar for anterior (P < .001) and posterior (P < .037) implants. No significant differences in implant stability and bone resorption between groups were noted. For fixed prostheses, anterior implants showed significantly higher Plaque Index, Gingival Index, and pocket depth than posterior implants (P < .001) after 12 months. However, no significant differences in implant stability and bone resorption between anterior and posterior implants were noted for both groups. CONCLUSION: Both fixed prostheses and milled bar prostheses could be used successfully for immediately loaded four-implant rehabilitations of the edentulous mandible, as they were associated with favorable clinical and radiographic outcomes after 1 year. However, milled bar may be more advantageous than fixed prostheses in terms of reduced plaque/gingival indices and probing depth.

Fully Digitally Guided Implant Surgery Based on Magnetic Resonance Imaging.

PURPOSE: The purpose of this study was to evaluate whether fully digitally guided implant surgery may be performed with sufficient accuracy based on printing virtually designed templates after matching a surface scan with the magnetic resonance imaging (MRI) dataset mimicking edentulous cases based on cadaver maxillae of pigs. MATERIALS AND METHODS: The palatal mucosa of five young pig cadavers was scanned with an intraoral scanner. High-resolution MRI of the jaws was performed, and the images were exported as DICOM files and uploaded into software for implant planning. Six implant osteotomies were virtually planned in each jaw. The intraoral surface scans were fused with the volumetric MRI data based on the palatal soft tissue, and virtual templates for guided implant surgery were created and exported as STL files. These were printed and the templates were used to perform flapless guided osteotomy, with the templates fitting on the soft tissue of the jaws alone. Cone beam computed tomography (CBCT) of the jaws was performed after osteotomy. These data were fused with the virtually planned osteotomies, and the 3D crestal, apical, and axial deviations between the virtually planned and physically performed osteotomies were determined. RESULTS: Matching the surface scans with the mucosa was possible in three cases automatically; additional manual corrections were necessary in two cases. Thirty osteotomies were performed by applying the printed mucosa-supported templates. The mean angular deviation between the planned and realized cavities was 3.29 degrees (0.3 to 11.1 degrees; SD = 2.5 degrees), the mean 3D apical deviation was 1.3 mm (0.22 to 3.98 mm; SD = 0.94 mm), and the mean crestal deviation was 1.76 mm (0.39 to 3.79 mm; SD = 0.88 mm). CONCLUSION: MRI in combination with the presented workflow may be used in edentulous cases for guided implant surgery. Further studies are needed to prove the promising accuracy of this alternative approach in clinical trials.

Immediate dental implant placement in calvarial bone grafts to rehabilitate the severely resorbed edentulous maxilla: A prospective pilot study.

PURPOSE: The aim of this study was to describe the surgical technique of immediate dental implant placement in calvarial grafts for augmentation of the severely resorbed maxilla and to assess the treatment results. METHODS: In 13 patients the maxilla was augmented with calvarial bone followed by simultaneous dental implant placement (total: 68 implants). In the frontal "knife edge" region, implants were inserted in the buccal plated area. In the maxillary sinus area, implants were inserted into alveolar bone that was plated buccally or palatally through the sinus window. After 4 months, the implants were retrieved and subsequently loaded. Per-operative and post-operative variables were scored. One bone biopsy sample was taken for histological analysis. RESULTS: The surgical procedure and wound healing was uneventful. During abutment connection after 4 months, all implants were fully osseointegrated with no signs of graft resorption. Radiographically, the mean (±SD) peri-implant bone loss after 1 year of functional loading was 0.23 ± 0.44 mm. No implants were lost. Histological examination revealed vital calvarial and maxillary bone with active remodeling. CONCLUSION: Immediate dental implant placement in calvarial bone grafts to rehabilitate severely resorbed maxilla is technically feasible and seems to have a high success rate.

Evaluation of Anatomical and Volumetric Characteristics of the Nasopalatine Canal in Anterior Dentate and Edentulous Individuals: A CBCT Study.

OBJECTIVE: To examine the nasopalatine canal (NPC) anatomical and volumetric measurements in anterior edentulous (AE) and anterior dentate (AD) individuals and to compare these findings according to sex, age, shape, and severity of resorption in the premaxilla. METHODS: Two hundred cone beam computed tomography images were divided into 2 groups: AE and AD. The diameter, the length of the NPC and the width, the length of the buccal bone anterior to the NPC were measured and recorded. Linear and volumetric measurement results were evaluated in terms of age, sex, dental status, shape, and severity of resorption. RESULTS: No significant differences were observed between the AE and AD groups in terms of the NPC volume (P = 0.289). In the AE group, the spindle shape had the highest volume, and in the same group, with aging, the volume significantly increased (P = 0.00). The mean NPC volume was found to be statistically significantly larger in males than females (P = 0.02). A statistically significant relation was observed between NPC volume and resorption status. CONCLUSION: Severe bone resorption due to sustained edentation complicated implant surgery because of the increase in incisive and nasal foramen diameters and decrease in buccal residual bone dimensions. The NPC volume was found fewer in edentulous patients, and by the resorption, the volume was decreased.