Molar Sites Research Articles

Stress Distribution in Implant-Supported Overdenture and Peri-Implant Bone Using Three Attachment Systems: A Finite Element Analysis

Background: This finite element analysis (FEA) evaluated stress distribution in implant-supported overdenture (ISO) and peri-implant bone using one extracoronal (ball) and two intracoronal (locator and Zest Anchor Advanced Generation (ZAAG)) attachment systems. Methods: In this in vitro study, the mandible was modelled in the form of an arc-shaped bone block with 33 mm height and 8 mm width. Two titanium implants were modelled at the site of canine teeth, and three attachments (ZAGG, locator, and ball) were placed over them. Next, 100 N load was applied at 90° and 30° angles from the molar site of each quadrant to the implants. The stress distribution pattern in the implants and the surrounding bone was analyzed, and the von Mises stress around the implants and in the crestal bone was calculated. Results: While minimum stress in peri-implant bone following load application at 30° angle was noted in the mesial point of the locator attachment, maximum stress was recorded at the distal point of the ball attachment following load application at 90° angle. Maximum stress around the implant following load application at 90° angle was noted in the lingual point of the ball attachment while minimum stress was recorded in the lingual point of the locator attachment following load application at 90° angle. Conclusions: According to the results, the locator attachment is preferred to the ZAAG attachment, and the ball attachment should be avoided if possible.

Peri-implant tissue stability in premolar and molar sites: a retrospective clinical and radiographic analysis.

The retrospective study was undertaken to assess the peri-implant tissue stability in premolar and molar sites clinically and radiographically for implants 7 years after loading. 408 implants placed in 275 patients from 2012 to 2020 and following a regular recall protocol were assessed for Modified Plaque Index (MPI), Sulcus Bleeding Index (SBI), pocket probing depth (PPD), and the peri-implant soft tissue dehiscence (PSTD) clinically and mesial bone loss (MBL) and distal bone loss (DBL) radiographically. Significant differences were found in MPI, SBI, and PPD amongst both men and women in the premolar and molar regions. The mean MBL and DBL were substantially greater in women than in men and marginally more in the maxilla than in the mandible. Maximum mean bone loss on either aspect of the premolar and molar implants was 2.80 ± 1.54 mm and 2.97 ± 0.96 mm for women. Implant success of 96.82% at 7 years was achieved and the patient satisfaction levels of 94.55% and 95.50% in the mandibular and maxillary arches, respectively, implied that patients were satisfied with the treatment. Women exhibited greater marginal bone loss on the mesial and distal aspects than men, with premolar implant sites demonstrating greater propensity for marginal bone loss than molar implant sites.

Panoramic prediction equations to estimate implant- to-mandibular canal dimensions in the mandibular posterior region: implications for dental implant treatment

BackgroundTo develop and cross-validate site-specific panoramic radiography (PAN) analysis prediction equations of implant-to-mandibular canal dimensions (IMCD) in mandibular regions posterior to the mental foramen, and to help determine in which instances CBCT technology will be a justified adjunct in clinical practice.MethodsIMCD by PAN (Pan-D) from implant site-specific regions (first premolar, second premolar, first molar, and second molar sites) were collected from 40- to 70-year-old adolescents. They were randomly assigned to validation (n = 144) and cross-validation (n = 148) groups. The cone-beam computed tomography (CBCT) technique was used as the criterion method for the estimation of IMCD (CBCT-D). The PAN analysis equations were developed using stepwise multiple regression analysis and cross-validated using the Bland–Altman approach.ResultsThere was a significant relationship between PAN-D and CBCT-D for both validation (R2 = 57.8 %; p < .001) and cross-validation groups (R2 = 52.5 %; p < .001). Root means-squared error (RMSE) and pure error (PE) were highest for the first molar (RMSE = 1.116 mm, PE = 1.01 mm) and the second molar region (RMSE = 1.162 mm, PE = 1.11 mm).ConclusionsPAN-D has the potential to be developed as an indirect measure of IMCD. However, the findings suggest to exclude scoring of the first and second molars when assessing IMCD via PAN. Use of CBCT may be justified for all IMCD estimations in the first and second molars regions.Trial registrationThis study has been registered and approved by the Ethics Committee of the Martin-Luther University, Halle, Germany (2020-034).

Risk Indicators Affecting the Survival of the Mandibular First Molar Adjacent to an Implant at the Mandibular Second Molar Site: A Retrospective Study.

This study aimed to compare the survival of mandibular first molars (MnM1s) adjacent to implants placed in mandibular second molar sites (ImM2s) with MnM1s adjacent to mandibular second molars (MnM2s) and to investigate risk indicators affecting the survival of MnM1s adjacent to ImM2s. A total of 144 patients who had MnM1s adjacent to ImM2s and MnM1s adjacent to MnM2s on the contralateral side were included in this study. Clinical variables and radiographic bone levels were evaluated. The survival of MnM1s adjacent to ImM2s or MnM2s was evaluated using a Kaplan–Meier analysis and Cox proportional hazards model. The 5-year cumulative survival rates of MnM1s adjacent to ImM2s and MnM2s were 85% and 95%, respectively. MnM1s adjacent to ImM2s of the internal implant-abutment connection type had higher multivariate hazard ratios (HR) for loss. MnM1s that had antagonists with implant-supported prostheses also had higher HR for loss. The multivariate HR for the loss of MnM1s adjacent to ImM2s with peri-implant mucositis was 3.74 times higher than MnM1s adjacent to healthy ImM2s. This study demonstrated several risk indicators affecting the survival of MnM1s adjacent to ImM2s. It is suggested that supportive periodontal and peri-implant therapy combined with meticulous occlusal adjustment can prolong the survival of MnM1s and ImM2s.

Evaluation of healing at molar extraction sites with ridge preservation using a non-resorbable dense polytetrafluoroethylene membrane: A four-arm cohort prospective study.

ObjectivesTo examine ridge dimensional changes and histologic parameters of healing when ridge preservation (RP) was performed at molar sites using dense polytetrafluoroethylene (dPTFE) membrane alone, without a bone graft.Material and MethodsEighteen patients had molar extraction and RP using dPTFE membrane alone. Ridge dimensions were measured using two standardized cone beam computerized tomography (CBCT) scans taken within 72 h and 3 months following extraction. Following a 3‐month healing period, an implant osteotomy was prepared using a trephine drill and bone cores were collected for histological analysis. Four‐arm analyses were performed using data from three previously published study arms of the same research group.ResultsThere was a significant change in the buccal ridge height between the four groups at all aspects of the socket. Alveolar ridge width reduction at 3 mm from crest for all aspects (mesial, midpoint, distal) of the socket showed statistically significant difference for dPTFE alone group compared to the other three groups. Percentage of vital bone formation (62.10%) was significantly greater in dPTFE alone group compared to the other groups.ConclusionsRP using dPTFE membrane alone in molar sites with intact socket walls showed successful outcomes in maintaining ridge dimensions and in histologic wound healing.

Clinical and radiographic evaluation of jumping distance management using a collagen matrix in flapless immediate implant placement.

Improvement in implant design has made implant dentistry a challenging treatment modality worldwide. This study aimed to investigate the efficacy of a xenogeneic collagen matrix in managing 3-4-millimeter gaps in flapless immediate implant placement. Twenty-two patients received 39 immediate implants via the flapless approach. Patients with intact bony walls, buccal bone thickness ≥2 mm and a jumping distance of 3-4 mm were included in this study. The gap between the implant and the socket walls was filled with a xenogeneic collagen matrix (Collacone®). The final clinical and radiographic evaluations were performed at least 24 months following functional loading. There was no early or late failure, and the implants showed a 100% survival rate. The mean mesial (0.28 ±0.39 mm) and distal (0.28 ±0.39 mm) marginal bone loss (MBL) at the site of incisors was not significantly different from the values at the site of premolars and molars (0.30 ±0.42 mm and 0.34 ±0.48 mm, respectively). The evaluation of the implant success index (ISI) score revealed no difference between the mandible and the maxilla (p = 0.700), or incisors compared with premolars and molars (p = 0.420). The only significant difference was in terms of distal MBL, which was higher in the maxilla (0.39 ±0.49 mm) than in the mandible (0.12 ±0.23 mm) (p = 0.040). Within the limitations of this study, it seems that the application of a xenogeneic collagen matrix to manage 3-4-millimeter gaps in carefully selected cases may bring promising outcomes.

Effect of ridge preservation at molar extraction sites with severe periodontitis on the Schneiderian membrane thickness changes: a pilot study

BackgroundInformation regarding the reaction of bone augmentation in terms to sinus mucosa thickness of periodontally compromised molar extraction sites is limited. This retrospective study aimed to analyze the effect of ridge preservation procedures following the extraction of molars with severe periodontitis on the healing pattern of adjacent maxillary sinus mucosal membranes.MethodsThirty-one periodontally compromised maxillary molar teeth either receiving ridge preservation (test group, n = 20) or undergoing spontaneous healing (control group, n = 11) were investigated. Cone-beam computed tomography (CBCT) scanning was performed before the extraction procedure and repeated 6 months later. The mucosa thickness (MT) of the adjacent periodontally compromised molar tooth was measured from CBCT images before tooth extraction and after 6 months of healing at nine assigned measurement points. The data were analyzed at α = 0.05.ResultsThe prevalence of pre-extraction maxillary sinus mucosal thickening was 60.0% and 63.6% in the test and control groups, respectively. The average MT of the thickened sinus mucosa before tooth extraction was 3.78 ± 2.36 mm in the test group and 4.63 ± 3.20 mm in the control group (P = 0.063). The mean mucosal thickening reductions in the thickened MT subjects after 6 months of healing were 2.20 ± 2.05 mm (test group) and 2.64 ± 2.70 mm (control group), P = 0.289. The differences of MT between the time prior to extraction and after 6 months of healing were statistically significant within both groups (P < 0.05).ConclusionsFollowing extraction of molars with severe periodontitis, a reduction in swelling of the Schneiderian membrane has been observed regardless of the addition of a DBBM socket graft. However, a mucosal thickness > 2 mm was still frequently observed.

Inter radicular bone dimensions in primary stability of immediate molar implants – A cone beam computed tomography retrospective analysis

PurposeThe purpose of the study was to analyze the dimensions of socket morphology, interradicular bone dimensions, root length and morphology, buccal cortical bone thickness and gap defect between the implant bone in mandibular molars with cone beam computed tomography (CBCT) for immediate molar implant (IMI) placement. Materials and methodsSample sizes of 300 mandibular 1st and 2nd molars were each selected from the CBCT scans by inclusion and exclusion criteria. CBCT measurements were performed for socket size morphology, mesiodistal width, and buccolingual cancellous bone width at the crest at the apex. Width of the buccal cortical plate at the crest and interradicular bone (IRB) at the apex, 3 mm cervical to the apex and 6 mm cervical to the apex. Vertical parameters from the crest to furcation (L1), length from furcation to the apex (L2) and mesiodistal root morphology were measured to analyze the root configuration. ResultsAll the parameters were analyzed for descriptive statistics for the mean and standard deviation. The majority were of Type B and C socket morphology with peri-implant bone defects of 2–2.5 mm, and the interradicular bone septum (IRB) was moderate for both first molar (1 M) and second molar (2 M) sites, but 2 M was shown to have less IRB than 1 M. Adequate buccal cortical bone thickness of 1.1 mm to 1.4 mm and buccolingual cancellous bone width were measured for both the 1 M and 2 M sites. ConclusionThe morphology of the molar extraction socket determines the adequate stability for IMI. In mandibular molar teeth, where interradicular bone is incompetent in providing good primary stability, in addition to interradicular bone, clinicians should look for support from the apical bone and interdental septal bone for attaining primary stability of IMI.

Effect of guide sleeve material, region, diameter, and number of times drills were used on the material loss from sleeves and drills used for surgical guides: An in vitro study

Statement of problemHow material loss from sleeves and drills is affected when different guide sleeve materials and different sizes of implant drills are used for different regions of surgical guides is unclear. PurposeThe purpose of this in vitro study was to compare the amount of material loss from different guide sleeves (zirconia and cobalt-chromium) and drills of different diameters during osteotomy preparation in different regions. Material and methodsThree tooth-supported surgical guides with sleeve holes positioned in the first premolar and second molar sites were prepared. Guide sleeves (Ø 2.20 mm, 3.40 mm, and 4.05 mm) were milled from zirconia (n=60) and cobalt-chromium (n=60) blocks. A total of 12 titanium nitride-coated stainless steel twisted drills (n=6 per sleeve material) of different diameters (Ø 2.00, 3.20, 3.85 mm) were used with corresponding sleeves during the drilling. The weight loss from the drills and the volume loss from the guide sleeves after drilling were analyzed by using multiple linear mixed effect models (α=.05). ResultsAccording to the 4-way ANOVA for volume loss from sleeves, no significant interaction was found among the 4 main effects (number of times a drill was used, region, diameter, and material), but interactions between the number of times a drill was used and diameter (P=.001) and between the number of times the drill was used and material were significant (P<.001). For weight loss from the drills, a significant interaction was detected between the number of times the drill was used and diameter (P=.024). ConclusionsLess sleeve material was lost when zirconia sleeves were used. All sleeves had more material loss in the molar region than in the premolar region. The diameter had varying effects on the amount of material loss from drills and sleeves. The sleeve material and the region did not affect the material loss from drills.

Comparison of two Surgical Procedures in the Management of Oroantral Fistula

Objective: To compare between double layer closure and buccal advancement flap in the management of Oro-antral fistula. Methodology: This Comparative cross sectional study was conducted on 30 patients with oral antral fistula in Maxillofacial Surgery Department, Liaquat University of Medical & Health sciences Hyderabad. The study was conducted from March 2013 to February 2019. Selection of patients was made on inclusion criteria of patient having OAF for more than 15 days, irrespective of location and side. Patients who developed Oro-antral fistula (OAF) because of any pathology or its treatment, and patient having bleeding tendency were excluded. Division of two groups to avoid any bias in this study was done by using random number table. Group-I was treated with buccal advancement flap while group-II with “double layer closure “with buccal fat pad” and 2nd layer with buccal advancement. The outcome was evaluated for any postoperative complications like wound dehiscence, necrosis, infection. Results: Males and females were 67% and 33% respectively. The mean age was 35.03±9.56 years. Maxillary molars were the common site for OAF. Maxillary first molar followed by second molar site was ranked according to frequency of this condition. Buccal advancement procedure was used in group A and in this cluster 86.6% cases were successful. In Group B, a double layered closure procedure was used and the success rate was 93.3% which is statistically not significant. Conclusion: Double-layered closure using BFP with buccal advancement flap should be kept as a valuable option in mind in the management of OAF. Key Words: Buccal Advancement Flap, Oro-Antral Fistula, Buccal Fat Pad, Double Layered Closed Technique.

Porous Bone Increases the Risk of Posterior Mandibular Implant Failure

Our recent study indicated that patients with osteoporosis had an increased risk for early and late implant failure perhaps due to a large cancellous space. Therefore, the purpose of the article is to explore the relationship between the amount of cancellous space in an implant site and implant failure. The authors conducted a retrospective cohort study on patients who received dental implants in the posterior mandible at the senior author's practice from January 1, 2008 to October 1, 2019. The primary outcome variable was time to implant failure. The primary predictor variable was the amount of cancellous bone between the buccal and lingual cortices (cancellous space). Other study variables included demographic variables, medical history variables, and implant site measurements. Statistical analysis was performed using descriptive statistics, chi-squared tests, single variable and multiple Cox proportional hazard analyses. The study cohort (n=220) was composed of 62.3% women and the average age was 58.2years. The median follow-up time was 3.5years (range: 1-12). Five-year survival rates for patients with a cancellous space of <4mm was 100%, with a cancellous space of 4-6mm was 95.3%, with a cancellous space of 6-8mm was 88.2%, and with a cancellous space of >8mm was 64.1%. In the final multivariate Cox proportional hazard model adjusting for age, gender, smoking status, site and buccal cortex width, cancellous space remained significantly associated with time to implant failure (aHR 1.7 per millimeter change [1.4 - 2.2], P<.0001). The width of the cancellous space and subsequent gap between implant and cortical bone should be considered when placing implants into the mandibular molar sites. When the patient presents for an implant in the mandibular molar region, if the cancellous space is large, the patient should be informed of the risk.

Sealing Socket Abutments (SSAs) in Molar Immediate Implants with a Digitalized CAD/CAM Protocol: Soft Tissue Contour Changes and Radiographic Outcomes After 2 Years

Immediate implant placement in molar sites has the potential to improve the patient experience by reducing the number of appointments and the overall treatment time. However, primary closure remains a technical challenge. The present prospective case series evaluated the soft tissue contours and the radiographic bone levels of 17 patients who received immediate implants in molar sites and a digitally customized CAD/CAM sealing socket abutment. At the 2-year follow-up, the mean buccal tissue contours at the most coronal portion were reduced horizontally by an average of 1 mm at 1, 2, 3, and 4 mm below the gingival margin. A mean 0.53-mm apical migration of the gingival margin was seen, and the mean interproximal bone level at the 2-year follow-up was 0.89 mm. The use of CAD/CAM-generated customized healing abutments in immediate molar sites yielded minimal hard and soft tissue changes at the 2-year follow-up.

Association between ridge morphology and complexity of implant placement planning in the posterior mandible

Statement of problemUncertainties regarding the 3D ridge morphology of the posterior mandible can greatly increase the risk of surgical complications during dental implant placement. By using cone beam computed tomography (CBCT) imaging and a computer-guided implant treatment software program before any invasive procedure, it is possible to assess ridge morphology and understand the surgical complexity and risk level. PurposeThe purpose of this radiological clinical study was to evaluate a large series of CBCT images to evaluate ridge shape variations along posterior mandibular edentulous regions and to clarify their associations with the level of implant planning complexity. Material and methodsOne hundred and twenty CBCT files were analyzed retrospectively for a total 240 hemimandibular sites. Images of each edentulous region of the mandibular first and second premolar and first and second molar sites were evaluated in the sagittal plane. Ridge morphology and implant planning complexity per site were assessed. Categorical variables were presented as number of events and percentages. The chi-square test was used to compare the categorical variables (P=.05). ResultsOf 491 partially edentulous mandibular sites, 235 were on the right, and 256 were on the left. Forty-two sites had a distal adjacent tooth, while 266 sites had no distal adjacent tooth. The sagittal bone sections demonstrated oblique (40.53%), straight (31.77%), S-shape (24.24%), hourglass (2.44%), and basal bone (1.02%) ridge morphologies. Implant complexity was deemed straightforward in 66.19% of sites, while 31.6% were identified as advanced and 2.54% as complex. When ridge morphology was evaluated from straight to basal-round bone shape, the implant complexity followed the same trend of change from a straightforward to complex procedure (P=.001) for edentulous second and first molar regions. No significant differences were noted at edentulous second premolar sites (P=.063). The missing second molar sites with oblique morphology were predicted to have 60.9% straightforward complexity, and first molar sites with oblique morphology had 55.8% straightforward implant complexity. Second premolars with straight ridge morphology had 71.7% straightforward complexity, whereas first premolars with the same shape had 92.5% straightforward implant complexity. ConclusionsCareful evaluation of sagittal CBCT images can provide significant clinical information regarding ridge shape and anticipated surgical complexity before and at the time of implant placement. Surgical complexity is greatest at the most posterior mandibular edentulous sites, and extra attention and caution should be exercised during the surgical planning phases of implant surgery.

Three-dimensional finite element analysis of different framework materials in implant-supported fixed mandibular prosthesis

Objective: To evaluate the biomechanical behaviors of different framework materials in implant-supported fixed mandibular prosthesis using three-dimensional finite element analysis. Methods: A model of implant-supported fixed mandibular prosthesis was established. The simulations were divided into six groups according to the framework materials: pure titanium, cobalt-chromium alloy, gold alloy, zirconia, polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK. An oblique load of 300 N with a 75° angle to the occlusal plane was applied from the lingual side on the buccal cusps of the two premolars and the first molar teeth. The stresses on implants, surrounding bones and frameworks were analyzed and compared among the framework materials both quantitatively and qualitatively. Results: In implant-supported fixed mandibular prosthesis model, the highest stresses were located around the neck of the implants and cortical bone during oblique loading among six designs. In addition, the stresses were concentrated on the buccal and distal cortical bone around the implants of the posterior region. Stress values of implants and cortical bones from low to high were as follows: zirconia, cobalt-chromium alloy, pure titanium, gold alloy, carbon fiber-reinforced PEEK, PEEK. The von Mises stress values of implant and cortical bone in the first molar site of PEEK framework material were 44.96 and 29.13 MPa, while the von Mises stress values of implant and cortical bone in the first molar site of zirconia framework material were 21.29 and 17.79 MPa. The zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework material. Conclusions: In implant-supported fixed mandibular prostheses, biomechanical analysis showed that the zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework materials.

Immediate implant in the posterior region combined with alveolar ridge preservation and sealing socket abutment: A retrospective 3D radiographic analysis.

Customized sealing socket abutment (SSA) has been claimed to optimize the peri-implant hard and soft tissues in type 1 implant placement. However, the evidence to claim the benefits of this technique over the use a conventional healing abutment remains weak. The aim of this retrospective study was to provide a 3D-radiographic evaluation of hard tissues changes following immediate implant placement in molar sites combined to ARP technique and installation of SSA. Baseline and follow-up (FU) CBCTs (from 1 to 5 years) of 26 patients were collected and included in the study. Baseline and FU CBCTs were superimposed and horizontal and vertical bone changes were assessed. A total of 26 patients and 27 implants were included. Horizontal bone remodeling was not significant in any of the measured areas except in the most cervical level, where a mean bone remodeling of 0.73 mm was found. Proximal and buccal vertical bone changes were not significant. Within the limits of a retrospective study, dimensional alveolar ridge changes 1 to 5 years after immediate implant placement in molar sites with simultaneous ARP technique and installation of SSA seem to be very limited.

Factors Affecting Implant Stability Quotients at Immediately and Conventionally Loaded Implants in the Posterior Maxilla: A Split-Mouth Randomized Controlled Trial.

To assess primary and secondary stability of variable-thread tapered implants in the posterior maxilla and analyze the impact of various factors on implant stability quotients (ISQs). Twenty-six subjects received 3-4 adjacent implants in the maxillary premolar-molar sextants to replace bilateral tooth loss. The implants on one side were immediately loaded with a provisional fixed prosthesis regardless of their primary stability. The contralateral control implants were conventionally loaded. Bone quality was subjectively recorded and primary stability was assessed by means of insertion torque values (ITVs) and ISQs in 4 directions. Secondary stability was measured by ISQ at definitive prosthesis delivery (3-3.5 months postoperatively), and 12 months after definitive loading. The impact of measurement direction, loading protocol, time, site-related (bone quality, implant position, crestal buccal bone thickness, apical cortical anchorage), and implant-related (implant dimensions, abutment height) variables on ISQs was assessed. For logistic reasons, ISQs were obtained for only 18 patients with 60 test and 60 control implants. Most of the implants (82%) at baseline had their lowest ISQ on the buccal aspect. There were no significant differences between ISQs measured in the buccal and palatal directions, or between ISQs in the mesial and distal directions. The mean of buccal and palatal ISQs was significantly lower than the mean of the 2 interproximal measurements at all evaluation periods. ISQs were not significantly different between the 2 loading groups at any time point. All implants showed a time-dependent increase in ISQs. Baseline ISQ correlated weakly with bone quality and ITV. None of the variables had a significant impact on baseline ISQs, except for implants in second molar sites which showed poorer primary stability than first premolars. Measurement direction and time are the most significant parameters affecting ISQs of variable-thread tapered implants in the posterior maxilla.

Age Affects Alveolar Bone Height and Width in Patients Undergoing Dental Implant Treatment: Findings from Computed Tomography Imaging

Dental implants may help improve the general health and quality of life in older adults with tooth loss. Accurate assessment of the alveolar bone is key to implant treatment. Several studies have examined the value of jaw morphology diagnostic imaging; however, few studies have evaluated age-related changes in alveolar bone height and width using computed tomography (CT) scanning. The purpose of this study was to assess age-related changes in alveolar bone height and width using CT scans of patients undergoing dental implant treatment. We analyzed CT scans of 1960 sites in 655 cases (225 men, 430women; age rage, 20-85 years; mean age, 60.96 years) obtained from June 2016 to December 2018. The mean alveolar bone height and width were the outcomes of interest. The participants were dichotomized by age into groups of 20-64 and 65-85 years. Alveolar bone height and width were classified into six groups by site; the values were examined by age. Analyses were performed with the Mann-Whitney U test and Spearman correlation coefficients. Statistical significance was established at P<0.05. The height of the upper anterior (P<0.001), upper premolar (P<0.001), upper molar (P<0.01), lower anterior (P<0.01), lower premolar (P<0.05), and lower molar (P<0.01) sites, and the width of the upper anterior (P<0.01), upper premolar (P<0.01), and upper molar (P<0.01) sites in the alveolar bone were significantly associated with age. The present findings suggest that the decline in upper alveolar bone height and width and lower alveolar bone height is associated with aging in the present cohort. These findings suggest that older people may require implant treatment that is predicated on bone grafting.

Interproximal contact loss between implant-supported restorations and adjacent natural teeth: A retrospective cross-sectional study of 83 restorations with an up to 10-year follow-up

Statement of problemInterproximal contact loss between implant-supported restorations and adjacent natural teeth is a frequently encountered complication that could negatively affect surrounding tissues and/or patient satisfaction with treatment. The effect of interproximal contact loss on peri-implant tissue health and patient awareness of food impaction is currently unknown. PurposeThe purpose of this retrospective cross-sectional study was to explore the effect of interproximal contact loss on peri-implant tissue health and determine whether interproximal contact loss leads to increased patient awareness of food impaction around the affected area. This study also aimed to identify whether specific patient or local factors could cause interproximal contact loss. Material and methodsEighty-three participants with posterior single-unit implant-supported restorations were examined. The mean follow-up time after prosthesis insertion was 4 ±2.2 years (range 4 months to 10.6 years). Interproximal contacts were evaluated by using waxed dental floss. Patient age, sex, implant location, opposing tooth status, presence of endodontically treated adjacent tooth, and regular use of an occlusal device at night were recorded. Peri-implant probing depths and the presence of bleeding on probing were also recorded. Each participant was asked to indicate whether they had noticed increased food impaction around their implant-supported restoration. Statistical analysis included nonparametric Mann-Whitney U tests, the Spearman rank-order correlation, the Pearson chi-squared tests, and the paired t test (α=.05). ResultsAmong all examined mesial contacts, 34.1% were recorded as open, with an overall mesial interproximal contact loss (open and loose contacts combined) incidence of 48.8%. Restorations placed in premolar sites exhibited significantly tighter mesial interproximal contacts compared with those placed in molar sites (U=566, P=.041). A significant negative correlation was found between follow-up time after insertion and mesial contact tightness (rs=−0.226, P=.041). ConclusionsInterproximal contact loss appears to increase over time, with more surfaces being affected after longer periods of service. This study did not find an association between interproximal contact loss and peri-implant inflammation as measured by bleeding on probing, with the exception of the distolingual implant surface. Participants with interproximal contact loss were more aware of food impaction around their implant crown. Use of an occlusal device at night did not prevent interproximal contact loss.

OPTICAL DENSITY OF DIFFERENT PARTS OF JAWS IN ORTHODONTIC PATIENTS DURING DENTOFACIAL DEVELOPMENT

The growth and development of the facial skeleton is closely related to the growth of the cervical division of the spinal column. With a total increase in rate of osteopenic diseases and diseases of periodontal tissues, computed tomography becomes a particular relevant diagnostic technique for assessing bone density. The aim of this study was to carry out a comparative analysis of the mineral density values of the jaw bone tissue and the mineral density values of the second cervical vertebra in patients with malocclusions. Materials and methods. We analyzed 22 computer tomograms of orthodontic patients and divided all cases into two age groups according to the periods of dentofacial development. The bone density of the second cervical vertebra and jaw bones was measured in various sections. Results. The optical bone density in the second cervical vertebra increases with age from 501±61.06 to 550.6±45.32. The densest area in both jaws is the alveolar ridge between the central incisors. The lowest values of optical density were found in the area of the upper jaw tuberosity in both groups. In the lower jaw, similar results of bone density were found out in the second cervical vertebra and the articular head, 436 HU and 557 HU in the groups I and II, respectively. In both jaws, the most similar densitometric indicators of bone density were found in the second cervical vertebra and the bifurcation site of the first molars. Only in the group II, this figure was 724.77±41.64 HU at p2&lt;0,01 in the lower jaw. Conclusions. Bone tissue densitometry by computed tomography is a highly informative diagnostic technique and can be used to diagnose the condition of the jaw bone tissue and to assess the quality of orthodontic treatment. The value of the second cervical vertebra is a stable indicator of mineral density in all age groups. The results obtained allow us to recommend applying these indicators for the comparative characteristic of change in mineral density in the alveolar processes of jaw bones to check the progress of orthodontic treatment.

Multivariate analysis of the influence of prosthodontic factors on peri-implant bleeding index and marginal bone level in a molar site: A cross-sectional study.

Peri-implant tissue condition can result from prosthodontic, surgical and bacteriological factors. This study investigated the effects of prosthodontic factors on peri-implant tissue. Subjects were 140 patients with 310 implants from Osaka University Dental Hospital. Prosthodontic factors examined were the connection type, the suprastructure retention type, the material of the abutment and the mesiodistal and buccolingual prosthetic form of the superstructure as emergence angle. The objective variables were the modified bleeding index (mBI) and marginal bone level (MBL). Statistical analysis was used as a generalized estimation equation. The taper joint had a significantly smaller MBL than the butt joint (P < .001). There was no significant difference in mBI and MBL between cement and screw retaining. Zirconium and titanium resulted in a significantly smaller mBI than gold alloy (zirconium/gold alloy: P = .037, titanium / gold alloy: P = .021), but there was no significant difference in the MBL. Both mBI and MBL tended to be smaller when the emergence angle was around 20° to 40°, although this difference was not significant. As a result of multivariate analysis, our findings suggest that to reduce MBL from the perspective of prosthodontic factors it is preferable to use an implant with a taper joint connection positioned with an emergence angle of 20° to 40°.