Edentulous Sites Research Articles

Papilla Formation in Response to Computer-Assisted Implant Surgery and Immediate Restoration.

This retrospective analysis was undertaken to evaluate the effect of immediate implant restoration using a computer-assisted technique in partially edentulous sites on interimplant and intertooth bone level stability and papilla formation. Nine partially edentulous patients received a total of 23 implants that supported immediately placed implant restorations. Planning was accomplished using a radiographic guide, which allowed visualization of the emergence profile from the platform of the implant to the cervical of the planned restoration. Guided implants were placed according to the manufacturer's instructions, and restorations were screw retained directly to the implant. Multiple implants were splinted at surgery with autopolymerizing resin. Measurements were made at a mean of 545 days (range 288-958) postoperatively on the basis of radiographs and photographs. Measures were: (1) distance from bone crest to platform, (2) bone crest to contact point, (3) interimplant distance at the outer diameter of the platform, and (4) papilla from highest point to a reference line. At follow-up time, the bone ridge was located higher than the implant platform (mean 0.57 mm) compared to implants whose interimplant distance was less than 3 mm (mean 0.27 mm). Mean increase of the bone level between insertion and approximate 1-year follow-up was 0.047 mm. The mean distance from the contact point to bone was 2.39/3.93 mm postoperatively, resulting in 91/71% papilla fill between implants and between implant and adjacent tooth, respectively. Computer-assisted surgery with the preplanned immediate restoration seems to be an effective method to minimize bone loss at the implant platform resulting in support for papilla.

Soft Tissue Surgical Procedures for Optimizing Anterior Implant Esthetics.

Implant dentistry has been established as a predictable treatment with excellent clinical success to replace missing or nonrestorable teeth. A successful esthetic implant reconstruction is predicated on two fundamental components: the reproduction of the natural tooth characteristics on the implant crown and the establishment of soft tissue housing that will simulate a healthy periodontium. In order for an implant to optimally rehabilitate esthetics, the peri-implant soft tissues must be preserved and/or augmented by means of periodontal surgical procedures. Clinicians who practice implant dentistry should strive to achieve an esthetically successful outcome beyond just osseointegration. Knowledge of a variety of available techniques and proper treatment planning enables the clinician to meet the ever-increasing esthetic demands as requested by patients. The purpose of this paper is to enhance the implant surgeon's rationale and techniques beyond that of simply placing a functional restoration in an edentulous site to a level whereby an implant-supported restoration is placed in reconstructed soft tissue, so the site is indiscernible from a natural tooth.

Assessment of bone mineral density in pre- and post-menopausal women using densitometric software: A pilot study

Objectives: The density of available bone in the edentulous site of the patient is arguably the primary determining factors in predicting final prosthetic treatment outcome. The aim of the study was to compare and correlate the quality of mandibular bone with the help of densitometric software available in Kodak 9000C and to further substantiate the results, morphometric analysis using orthopantomograph (OPG) and quantitative ultrasound of calcaneus bone. Materials and Methods: Twenty premenopausal and twenty postmenopausal women were selected for the study with edentulous span in the mandibular second premolar and first molar region. Bone density of the edentulous span was calculated using the digital Kodak software 9000C for all the OPGs. Various radiomorphometric indices were measured on the OPG. Results were statistically analyzed. Results: The results proved that there was a statistically significant difference in the bone densitometric values for digital OPG readings, ultrasound values, mandibular cortical index, antegonial index, for pre- and post-menopausal women. Conclusion: Within the limitations of the study, the use of densitometric software yielded positive results. The results supported the fact that bone density reduces in postmenopausal women and can be used as an effective aid to quantify the bone mineral density which ultimately plays a significant role in prosthetic implant outcome. CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY The use of densitometric software could be used independently to measure bone density in future. An integrated team approach between the implantologist, prosthodontist, and radiologist provides a customized treatment plan, thereby, optimal patient care.

Prosthetic rehabilitation of a traumatic mandibular defect using alveolar distraction and an implant-supported hybrid prosthesis: A clinical report

Prosthetic rehabilitation of edentulous sites with concomitant alveolar deficiency is always an esthetic and functional challenge. In the current case, the advantages of distraction osteogenesis and hybrid prosthesis with a cast metal framework were used to restore esthetics and function. The surgical elegance of distraction osteogenesis combined with the variety of features of hybrid prosthesis ensured successful rehabilitation, patient comfort and ease of maintenance. This case report highlights the need for meticulous preoperative planning and selection of the right options, both surgical and prosthetic to effectively restore complex oral defects using implants. Traumatic defects are mostly accompanied by hard and soft tissue loss. This report describes the surgical and prosthetic treatment of a patient with a traumatic mandibular defect. The trauma resulted in the loss of numerous mandibular teeth and extensive loss of bone particularly in the anterior mandible. In order to restore the lost hard and soft tissues, the treatment plan comprised of alveolar distraction osteogenesis in the anterior mandible followed by an implant supported screw-retained FP-3 prosthesis. This article also describes a technique to ensure a passive well-fitting cast metal framework for the fixed removable screw-retained hybrid prosthesis. Clinical Relevance to Interdisciplinary Dentistry Placement of implants in compromised edentulous ridges often results in a compromised final prosthetic outcome. This case report describes an interdisciplinary approach to manage hard and soft tissue ridge defects using alveolar distraction osteogenesis, followed by implant placement and prosthetic rehabilitation using a hybrid denture. The integration of the faculties of prosthodontics, oral and maxillofacial surgery, and oral and maxillofacial radiology was the key factor that determined the successful completion of this complex and technically demanding case.

Cone Beam Computerized Tomography Measurement of Alveolar Ridge at Posterior Mandible for Implant Graft Estimation.

Damaging the inferior alveolar nerve (IAN) is the most serious complication when harvesting an autogenous graft from posterior mandible. The objective of this study was to use cone beam computerized tomography (CBCT) to measure dimensions of the alveolar ridge in the posterior mandible for estimation of a safe graft size, and then analyze how it is related to the gender, age, and dentition status of subjects. CBCT scans were screened to include 59 subjects without interfering pathologies. Alveolar height was measured from the alveolar crest to superior border of IAN and also to the inferior border of the mandible. Alveolar width (from buccal to lingual cortical plates) and buccal bone thickness (from buccal cortical plate to mandibular molar mesial root buccal surface) were measured at the coronal, middle, and apical thirds divided from the alveolar crest to the IAN. It was found that males and dentate sites had larger alveolar dimensions than did females and edentulous sites, respectively. Bone volume did not correlate significantly with age. Buccal bone thicknesses increased from coronal to apical and from the first to the third molar generally. A larger bone graft could be harvested from male than female patients, with a mean harvestable graft dimension (height × width in mm) for male was 15.5 × 3.2, and for female was 14.1 × 2.9. In conclusion, males and dentate arches demonstrate larger alveolar volumes than do females and edentulous regions, respectively. Larger alveolar grafts can be harvested from males compared to the females. Age does not seem to affect alveolar dimension/graft volume.

Bone dimensions in the posterior mandible: a retrospective radiographic study using cone beam computed tomography. Part 2--analysis of edentulous sites.

A precise radiographic evaluation of the local bone dimensions and morphology is important for preoperative planning of implant placement. The purpose of this retrospective study was to analyze dimensions and morphology of edentulous sites in the posterior mandible using cone beam computed tomography (CBCT) images. This retrospective radiographic study measured the bone width (BW) of the mandible at three locations on CBCT scans for premolars (PM1, PM2) and molars (M1, M2): at 1 mm and 4 mm below the most cranial point of the alveolar crest (BW1, BW2) and at the superior border of the mandibular canal (BW3). Furthermore, the height (H) of the alveolar process (distance between the measuring points BW1 and BW3), as well as the presence of lingual undercuts, were analyzed. A total of 56 CBCTs met the inclusion criteria, resulting in a sample size of 127 cross sections. There was a statistically significant increase from PM1 to M2 for the BW2 (P < .001), which was not present for BW1 and BW3 values. For the height of the alveolar process, the values exhibited a decrease from PM1 to M2 sites. Sex was a statistically significant parameter for H (P = .001) and for BW1 (P = .03). Age was not a statistically significant parameter for bone width (BW1: P = .37; BW2: P = .31; BW3: P = .51) or for the height of the alveolar process (P = .41) in the posterior mandible. Overall, 73 (57.5%) edentulous sites were evaluated to be without visible lingual undercuts; 13 (10.2%) sites exhibited lingual undercuts classified as influential for implant placement. Precise evaluation of the alveolar crest by cross-sectional imaging is of great value to analyze vertical and buccolingual bone dimensions in different locations in the posterior mandible. In addition, CBCTs are valuable to diagnosing the presence of and potential problems caused by lingual undercuts prior to implant placement.

Sinus Width Analysis and New Classification with Clinical Implications for Augmentation

To measure the distances between the medial and lateral sinus wall (sinus width [SW]) at different levels on cone beam computed tomography (CBCT) and apply those SW values to formulate a new sinus classification. Edentulous sites adjacent to maxillary sinuses with inadequate residual bone height (RBH) were included from the CBCT database. SW was measured at the heights of 1, 3, 5, 7, and 9 mm from the sinus floor. Mean SW was stratified into different groups by RBH, study sites (first and second premolars and molars), and measurement levels. Statistical analyses were conducted with commercially available software (IBM SPSS Statistics 19, SPSS Inc., Chicago, IL, USA). A total 186 patients (mean age 50.4 years) with 267 edentulous sites were included. Mean SW was wider at molar sites, higher measurement levels, and sites with less RBH. Narrow, average, or wide sinuses were classified based on the 33rd and 67th percentile SW values at 1-, 5-, and 9-mm measurement levels, respectively. SW at different levels relating to sinus floor elevation was measured. The proposed classification could contribute to estimate the difficulty of sinus augmentation, useful for the selection of surgical approaches. Further studies are required to testify its clinical implications.

The feasibility of using coronally advanced flap with an extracellular matrix membrane for treating gingival recession defects: a preclinical study.

The guided tissue regeneration (GTR) procedure has been demonstrated to successfully correct gingival recession (GR) defects. The aim of this study was to assess the feasibility of using the combination of a coronally advanced flap (CAF) with an extracellular membrane (ECM) to correct GR. GR defects were induced in the maxillary posterior region in five baboons. A 3-month healing period followed before the ECM was placed over the defect and covered with a CAF. Probing depth (PD), recession depth (RD), recession width (RW), and keratinized tissue width (KTW) were measured at baseline and 3 months postoperatively. Block biopsies of the treated areas were submitted for histologic review after a healing period of 3 months. There were no significant differences between the test (ECM + CAF) and control (CAF) groups in terms of changes in PD, RD, RW, and KTW after 3 months of treatment. However, significant differences have been noted for preoperation and postsurgery RD and RW values for both the control and test groups. Histomorphometric results showed minimal alveolar bone and connective tissue replacing the ECM membrane. CAF (either with or without the use of an ECM) is effective for the treatment of GR defects.

Vascularised fibula osteocutaneous flap for mandibular reconstruction and multiple implant retained fixed prosthetic rehabilitation of a patient with mandibular ameloblastoma

Ameloblastomas are rare, benign dental tumours representing 1% of the oral tumours and cysts.1 The most common site for ameloblastoma is mandibular molar region. It is an aggressive benign tumour of epithelial origin that has generally been treated surgically for metastases. Treatment by wide excision is curative in up to 95% of cases. Chana et al2 proposed a 1–2 cm normal margin, and the large defect left after resection warrants reconstruction preferably with the fibula osteocutaneous flap. Taylor in 19753 first described vascularised fibula graft for composite reconstruction of the bone and soft tissue defect. After demonstrating that osteotomies can be performed in vascularised fibula grafts without compromising the viability of the bone segment, these grafts became the state of art reconstruction method after mandible ablation. The free fibula flap provides the greatest bone length and is suitable to accept dental implants. Osseointegrated implants have become generally accepted for prosthodontic management.4 The application of endosseous implants in combination with bone grafting for jaw reconstruction has allowed for improved results. Different types of osseointegrated implants have been placed either simultaneously with bone grafts5, 6 or at a later stage after the bone grafts have healed. In this case report a 23-year-old female patient underwent left hemimandibulectomy because of ameloblastoma. Fibula was osteotomised and reconstructed to resemble mandible shape and fixed to reconstruction plate with intact pedicle. Implants were placed four months after surgery and prosthetic rehabilitation of the edentulous site was accomplished.

Efficacy of soft tissue augmentation around dental implants and in partially edentulous areas: a systematic review

To review the dental literature in terms of efficacy of soft tissue augmentation procedures around dental implants and in partially edentulous sites. A Medline search was performed for human studies augmenting keratinized mucosa (KM) and soft tissue volume around implants and in partially edentulous areas. Due to heterogeneity in between the studies, no meta-analyses could be performed. Nine (KM) and eleven (volume) studies met the inclusion criteria. An apically positioned flap/vestibuloplasty (APF/V) plus a graft material [free gingival graft (FGG)/subepithelial connective tissue graft (SCTG)/collagen matrix (CM)] resulted in an increase of keratinized tissue (1.4-3.3 mm). Statistically significantly better outcomes were obtained for APF/V plus FGG/SCTG compared with controls (APF/V alone; no treatment) (p < 0.05). For surgery time and patient morbidity, statistically significantly more favourable outcomes were reported for CM compared to SCTGs (p < 0.05) in two randomized controlled clinical trials (RCTs), even though rendering less keratinized tissue. SCTGs were the best-documented method for gain of soft tissue volume at implant sites and partially edentulous sites. Aesthetically at immediate implant sites, better papilla fill and higher marginal mucosal levels were obtained using SCTGs compared to non-grafted sites. An APF/V plus FGG/SCTG was the best-documented and most successful method to increase the width of KM. APF/V plus CM demonstrated less gain in KM, but also less patient morbidity and surgery time compared to APF/V plus SCTG based on two RCTs. Autogenous grafts (SCTG) rendered an increase in soft tissue thickness and better aesthetics compared to non-grafted sites.

Ridge alterations following grafting of fresh extraction sockets in man. A randomized clinical trial

To evaluate dimensional alterations of the alveolar ridge that occurred following tooth extraction at sites grafted with Bio-Oss(®) Collagen. Twenty-eight subjects with maxillary incisors, canines, and premolars scheduled for extraction were included. The tooth was carefully removed. The patients were randomly assigned to a test or a control group. In the test group patients, Bio-Oss(®) Collagen was placed in the fresh extraction socket while in the controls no grafting was performed. Radiographic examination (cone beam computed tomograms, CBCT) was performed immediately after tooth extraction and socket treatment. Four months later, a new CBCT was obtained. In the radiographs, (i) the distance (mm) between base of the alveolar process (apex) and the buccal and palatal crests was determined, (ii) the outer profile of alveolar process of the experimental sites was outlined, and the cross section of the area (mm(2) ) determined. After 4 months of healing, the buccal and to a less extent also the palatal bone plate had become markedly reduced in height. The placement of a biomaterial in the socket failed to prevent resorption of the buccal and palatal bone walls. The cross-sectional area of the control ridge was reduced about 25% and of the test ridge with 3%. The placement of a xenograft in fresh extraction sockets markedly counteracted the reduction in the hard tissue component of the edentulous sites.

Assessment of hard and soft tissue changes around Implants: A clinico-radiographic in vivo study

Introduction: Microbial plaque is the main etiologic factor which causes disease in soft tissue around dental implants. The purpose of this study was to evaluate the bone level around implants using conventional radiography. They were evaluated for radiographic changes in the peri-implant crestal bone at intervals of 1, 3 and 6 months. The radiographic findings were correlated with clinical parameters of mobility, probing depth, bleeding, etc. Aim: The aim of the present study was to evaluate the hard and soft tissue changes around two-stage implant both radiographically and clinically to assess the success of implants. Materials and Methods: Seven patients with 10 dental implants were examined clinically for 6 months after prosthodontic treatment. Plaque index and health indices of soft tissue including pocket depth, mobility, bleeding index, calculus and gingival index were measured. Marginal crestal bone loss and peri-implant radiolucency were checked radiographically. The criteria both subjective and objective were used to evaluate the success of the implant process. The necessary statistical analysis was performed for radiographic and clinical evaluation methods. Results: The results of this study showed that the values of all clinical criteria under study had no significant changes from baseline to 6 months. The vertical crestal bone loss on the mesial and distal side was within the normal range of bone loss given by Branemark. There was no mobility and no peri-implant radiolucency around any of the implants. Conclusion: Our study clearly demonstrated that in a group of patients with no periodontal disease the survival rate of two-stage, countersunk, submerged implants in the edentulous sites is 100% during the follow-up period of 6 months.

A Comparative Study of Bone Resorption between Implant Placement Sites and Non-Implant Placement Sites after Autogenous Block Bone Grafts in the Anterior Maxilla

The aim of this study was to compare the bone resorption differences between implant placement sites (IPS) and non-implant placement sites (NIPS) after autogenous block bone grafts in the anterior maxilla. Fourteen patients (58 edentulous sites) with alveolar atrophy in the anterior maxilla were treated with autogenous block bone grafts. CBCT examinations were performed at 1 month before surgery (T0), immediately after surgery (T1), 3 to 4 months after surgery (T2), 6 to 7 months after surgery before implant placement (T3), 12 to 13 months after surgery (T4), and the longest follow-up point (T5). Alveolar crestal and basal bone width (ACBW, ABBW), and alveolar bone height (ABH) were measured and divided into IPS (30 sites) and NIPS (28 sites). All results were compared by the Wilcoxon Signed Rank test. The bone resorption changes for both groups were the same. For these three parameters, ACBW didn’t change significantly from T2 to T3 and T4 to T5, ABBW didn’t change at every period from T2 to T5, and ABH didn’t change from T4 to T5. The bone resorption volume of ACBW and ABH in NIPS were more than in IPS after implant placement surgery, while the volume of ABBW was similar in both groups. At T5, the bone resorption percentages of ACBW, ABBW, and ABH were 25.57%, 16.85% and 43.84% in IPS, and 33.55%, 15.92% and 46.44% in NIPS. A more rapid loss of alveolar crest in NIPS resulted from implant placement surgery, and this reminded us of the importance of immediate implant placement.

Interleukin-1β level in peri-implant crevicular fluid and its correlation with the clinical and radiographic parameters.

Background and Objectives:Assessing only the clinical and radiographic parameters for evaluation of dental implants may not be enough as they often reflect extensive inflammatory changes in the periodontal tissues. As peri-implant crevicular fluid (PICF) can give us a more prompt and objective measure of the disease activity, the purpose of this case series is to assess the peri-implant health status of single tooth dental implants not only clinically and radiographically but also biochemically.Materials and Methods:Thirteen patients were subjected to dental implants at single edentulous sites using a conventional surgical approach. At baseline, 6 months, and 12 months after implant placement, the clinical and radiographic parameters were recorded. Additionally, IL-1β in PICF was estimated using the ELISA kit at 6th and 12th month.Results:The clinical and radiographic parameters differed significantly around the implants at different time intervals with IL-1β levels showing highly significant differences between 6 months (31.79 ± 12.26 pg/μl) and 12 months (113.09 ± 51.11 pg/μl). However, Spearman's correlation coefficient showed no correlation with the clinical and radiographic parameters.Interpretation and Conclusion:Assessment of the various parameters confirmed that all the implants had a healthy peri-implant status. Although the levels of IL-1β in PICF were elevated at the 12th month, they were well within the healthy range as observed by previous studies. This indicates that IL-1β, a biochemical marker, can be used as an adjunct to clinical and radiographic parameters in the assessment of EARLY inflammatory changes around implants.

Paradigm shift in the management of the atrophic posterior maxilla.

When the posterior maxilla is atrophic, the reference standard of care would be to perform sinus augmentation with an autologous bone graft through the lateral approach and delayed implant placement. However, placement of short implants with the osteotome sinus floor elevation technique and without graft can be proposed for an efficient treatment of clinical cases with a maxillary residual bone height of 4 to 8 mm. The use of grafting material is recommended only when the residual bone height is ≤4 mm. Indications of the lateral sinus floor elevation are limited to cases with a residual bone height ≤ 2 mm and fused corticals, uncompleted healing of the edentulous site, and absence of flat cortical bone crest or when the patient wishes to wear a removable prosthesis during the healing period. The presented case report illustrates osteotome sinus floor elevation with and without grafting and simultaneous implant placement in extreme conditions: atrophic maxilla, short implant placement, reduced healing time, and single crown rehabilitation. After 6 years, all placed implants were functional with an endosinus bone gain.

Implant loading protocols for partially edentulous patients with extended edentulous sites--a systematic review and meta-analysis.

The aim of this study was to systematically review the evidence for immediate implant loading in partially edentulous patients with extended edentulous sites and evaluate potential treatment modifiers. An electronic search was performed in Medline, Embase, and Central to identify studies investigating the outcome of implants subjected to immediate loading (IL) (less than 1 week), early loading (EL) (1 week to 2 months), or conventional loading (CL) (more than 2 months) with implant-supported fixed dental prostheses (IFDPs) in partially edentulous patients with extended edentulous sites, ie, at least two adjacent teeth are missing. Only human studies with at least 10 cases and a minimum follow-up time of 12 months, reporting on solid-screw-type implants with rough surfaces and a diameter of at least 3 mm, were included. Weighted means of implant survival rates and risk ratios for implant survival at 1 year using meta-analytic tools were calculated to perform the following comparisons: IL vs EL, IL vs CL, and IL in the maxilla vs mandible. Noncomparative studies reporting on IL and EL protocols were summarized through descriptive methods. The search provided 3,872 titles, 837 abstracts, and 444 full-text articles. A total of 24 publications that comprised six comparative studies (five randomized controlled trials, one nonrandomized controlled trial) and 18 noncomparative studies were included for analysis. The comparison of weighted mean survival rates revealed no statistically significant difference between IL (97.9%) and EL (97.8%, P = .9405), and between IL (100%) and CL (99.3%, P = .3280). Meta-analysis showed no statistically significant difference in implant survival at 1 year between IL and EL (RR 0.90; 95% CI 0.30, 2.70; P = .502). A meta-analysis comparing IL and CL could not be performed due to the low number of failures. No statistically significant difference was found for IL implants placed in the maxilla vs the mandible (RR 1.55; 95% CI 0.49, 4.84; P > .05). Due to the small number of IL implants placed in the anterior, a comparison between implant survival in anterior vs posterior zones was not performed. Treatment modifiers were bone quality, primary stability, insertion torque, ISQ values, implant length, the need for substantial bone augmentation, the timing of implant placement, and the presence of parafunctional and smoking habits. IL presents similar implant survival rates as EL or CL for partially edentulous patients with extended edentulous sites in the posterior zone, as long as strict inclusion/exclusion criteria are followed. There is a lack of evidence for IL of multiple implants in the anterior zone of partially edentulous patients. Preliminary evidence suggests that IL may be equally successful in either the maxilla or mandible. Further research is needed before IL in partially edentulous patients with extended edentulous sites can be recommended in everyday practice.

Early molecular assessment of osseointegration in humans

To determine the early temporal-wide genome transcription regulation by the surface topography at the bone-implant interface of implants bearing microroughened or superimposed nanosurface topology. Four commercially pure titanium implants (2.2×5.0mm) with either a moderately roughened surface (TiOblast) or super-imposed nanoscale topography (Osseospeed) were placed (n=2/surface) in edentulous sites of eleven systemically healthy subjects and subsequently removed after 3 and 7days. Total RNA was isolated from cells adherent to retrieved implants. A whole-genome microarray using the Affymetrix Human gene 1.1 ST Array was used to describe the gene expression profiles that were differentially regulated by the implant surfaces. There were no significant differences when comparing the two implant surfaces at each time point. However, the microarray identified several genes that were differentially regulated at day 7 vs. day 3 for both implant surfaces. Functionally relevant categories related to the extracellular matrix (ECM), collagen fibril organization, and angiogenesis were upregulated at both surfaces (day7 vs. day3). Abundant upregulation of several differential markers of alternative activated macrophages was observed (e.g., MRC1, MSR1, MS4A4A, SLC38A6, and CCL18). The biological processes involved with the inflammatory/immune response gene expression were concomitantly downregulated. Gene regulation implicating collagen fibrillogenesis and ECM organization as well as the inflammatory/immune responses involving the alternative activated pathway are observed in implant adherent cells at early (3-7days) after implantation. These gene expression events may indicate a pivotal role of collagen fibrillogenesis as well as immunomodulation in altering bone accrual and biomechanical physical properties of the implant-bone interface.

Palatonasal Recess on Medial Wall of the Maxillary Sinus and Clinical Implications for Sinus Augmentation via Lateral Window Approach

Anatomic variations of the maxillary sinus determine the degree of difficulty in performing sinus augmentation. Whereas some variations, e.g., the septum and morphology of the sinus, have been extensively studied, the structure of the medial wall has never been investigated. The aims of this study are to measure the location and angulation of the palatonasal recess (PNR) on the medial wall and identify risk sites that are related to the shape of the PNR. Cone-beam computed tomography (CBCT) scans were screened from the University of Michigan School of Dentistry database. Edentulous sites with <10 mm between the floor of the maxillary sinus and the alveolar crest were selected. The residual ridge height (RH), the distance between the PNR and the alveolar crest, and the angulation of the PNR were measured on the selected sagittal planes. The percentage of sites (risk sites) with recesses that were <90° and <15 mm from the alveolar crest was calculated. The PNR location and angulation were compared among premolar and molar edentulous sites. Two hundred seventy-four sites were studied. The mean ± SE PNR location was 14.2 ± 2.8 mm, 13.1 ± 2.2 mm, and 12.5 ± 2.5 mm for the second premolar, first molar, and second molar sites, respectively, with significant differences between the second premolar and second molar sites. The mean PNR angulation was 109.8° ± 25.3°, 121.6° ± 22.1°, and 144.9° ± 23.1° in the corresponding sites, with significant differences among the site groups. The respective percentages of risk sites were 15%, 8.2%, and 2.4% in the second premolar, first molar, and second molar sites. Maxillary sinuses with acute-angled PNRs might present a challenge for performing sinus augmentation. Therefore, this anatomic structure should be carefully evaluated.

A 3-Year Multicenter Study of Marginal Bone Level and Soft Tissue Health of a 1-Piece Implant

The study evaluated 1-piece implants in daily clinical situations. One-piece implants restoring both single teeth and partially edentulous sites were included. A single-stage procedure was used with immediate provisionalization within 24 hours after surgery. The definitive prosthesis was delivered within 6 months of implant insertion. One hundred fifteen implants have been placed in 84 patients at 4 centers. Two implants failed resulting in a cumulative survival rate of 98.3%. Normal periimplant mucosa and no visible plaque were observed in most of the implants. The soft tissue papilla scores improved considerably over time P < 0.001. Patient assessment improved significantly from implant insertion to the 3-year visit, P < 0.001. The mean bone level at implant insertion, 6-month, and 1-, 2-, and 3-year visits was 0.42, -0.58, -0.69, -0.80, and -0.66 mm, respectively. The mean change in bone level from implant insertion to 6 months and 1, 2, and 3 years was reported as -1.02, -1.12, -1.26, and -1.07 mm, respectively. The results indicate that this implant has the ability to preserve both hard and soft tissues' architecture.

Digital 3D image of bimaxillary casts connected by a vestibular scan

The task of three-dimensionally aligning digital images of scans taken from maxillary and mandibular casts can be accomplished by scanning an interocclusal record, but vestibular scanning is also an option. The present study addressed whether this latter technique is precise enough to be used in orthodontic practice. A total of 10 pairs of casts representing different types of tooth and jaw malposition were scanned with a photo-optical scanner (Activity 102; Smart Optics, Bochum, Germany). After obtaining detailed single scans of each upper and lower jaw, each pair of casts was rigidly aligned with instant glue. Subsequently, three vestibular scans were taken and were then merged with the single-jaw scans to form virtual bimaxillary models. These virtual models were superimposed with each other and analyzed, using the structures of the mandible as constant and documenting the highest occlusal and vestibular deviations measured on each maxillary tooth or gingival region. Descriptive analysis and a mixed linear model were performed with SPSS and SAS. The greatest deviations between the virtual bimaxillary models averaged 37 ± 28 μm. No significant differences were seen between tooth sites along the dental arch, dentate versus edentulous sites, or occlusal versus vestibular surfaces. The mean of the greatest deviations between repeated scans were found to be 28 ± 14 μm (vestibular scans) and 15 ± 8 μm (single-jaw scans). The presented approach of generating bimaxillary study models in a virtual environment with the help of vestibular scans meets the precision requirements for use in orthodontics and can be employed in further studies.