Implant stability and clinical outcome between implant placement using internal sinus floor elevation with alloplastic bone material grafting and without grafting: A 1-year randomized clinical trial.

OBJECTIVE: To compare implant stability and clinical outcome in implant placement between osteotome sinus floor elevation (OSFE) with biphasic calcium phosphate (BCP) which consisted of 30% of hydroxyapatite (HA) and 70% of beta-tricalcium phosphate (ß -TCP) grafting material and OSFE without using bone grafting material. The research questions is whether the BCP provides any benefit in OSFE or not. MATERIALS AND METHODS: Thirty patients (30 implants) with a single edentulous area of upper premolar or molar were randomly separated into OSFE with BCP (n = 15) and OSFE without grafting (n = 15). The patients were reevaluated 3, 6, 9, and 12 months after implant loading. The clinical assessments (implant stability quotient (ISQ), implant survival-failure rate, and surgical complication) were analyzed. Together with radiographic assessments in 2D (endo-sinus bone gain (ESBG), mean marginal bone change (MMBC)) and 3D (endo-sinus bone gain in CBCT (ESBG-CT)) were evaluated, with a mean follow-up time of at least 12 months of functional loading and prosthetic complication. RESULTS: 20 remaining implants (OSFE with BCP, n = 10; OSFE without grafting, n = 10) were analyzed. Mean ISQ was 79.18 ± 3.43 in 1-year follow-up (ISQ; OSFE with BCP = 78.72 ± 3.46, OSFE without grafting = 79.65 ± 3.52). ISQ in both groups increased steadily without significant differences in each follow-up. (p = 0.56). In radiographic evaluation, at 6-, 9-, and 12-month, OSFE without grafting group showed statistically significant lower MMBC (p < 0.05). The 1-year clinical results showed that 2 implants failed in OSFE with BCP, and 1 implant failed in OSFE without grafting. CONCLUSIONS: Graft material "BCP" (HA30:TCP70) coupled with OSFE presents no extraordinary benefit in implant stability, clinical and radiographic outcome in 1-year follow-up. CLINICAL RELEVANCE: Clinically, OSFE with grafting materials provides no additional benefit. CLINICAL TRIAL REGISTRATION NUMBER: TCTR20210517008 (date of registration: May 17, 2021).

Computerised occlusal analysis of mini-dental implant-retained mandibular overdentures: A 1-year prospective clinical study.

Occlusal analysis is a substantial tool for the functional improvement evaluation after using implant-retained overdenture comparing to complete denture without dental implant retaining. To evaluate occlusal pattern, chewing force distribution in mini-dental implant-retained mandibular overdentures by computerised occlusal analysis system and to compare patient satisfaction after 1-year function. Thirty-one patients wearing complete dentures were included in the study. Prior to mini-dental implant-retained treatment, all patients were assessed for occlusion and force distribution using computerised occlusal analysis system (T-Scan® ), and then, all patients received two mini-dental implant-retained mandibular overdentures. Mini-dental implants were immediately loaded using low vertical profile attachments (Equator® ). T-Scan® was used to evaluate chewing force and force distribution at 1 day, 3 months, 6 months and 12 months. The patient satisfactions before implant placement and after 1 year were evaluated using questionnaires which included satisfaction of denture quality, psychosocial behaviour and chewing efficiency modified from the validated questionnaires. Clinical evaluation of two mini-dental implant-retained mandibular overdentures showed 100% success rate after 1 year. T-Scan® demonstrated that maximum occlusal contact force increased continuously. The force distribution; the tooth contact number increased over the period. At 1-year follow-up, overall patient satisfaction was significantly greater than before receiving mini-dental implant treatment (P < .001). Using computerised occlusal analysis, mini-dental implants improve complete denture function significantly in terms of maximum occlusal contact force, tooth contact number without the impairment of force distribution. The oral function of the patients has been enhanced.

Comparative study of torque resistance and microgaps between a combined Octatorx-cone connection and an internal hexagon implant-abutment connection.

STATEMENT OF PROBLEM: Although the implant-abutment connection may prevent crestal bone loss around dental implants, its failure often leads to treatment failure. Microgap and micromovement of the implant-abutment connection could be causes of bone resorption around dental implant neck. PURPOSE: The purpose of this study was to compare torque resistance and microgaps between a new cone and index connection (Octatorx) and an internal hexagon implant-abutment connection (Internal hex). MATERIAL AND METHODS: Twenty Octatorx and 20 internal hexagon connections were attached with retaining screws at 30 Ncm. In a torsion resistance test, 10 of each type of connection were attached to a universal testing machine. Torque resistance with 90 degrees per minute rotation speed was recorded. For microgap measurement, each of 10 connections was embedded in clear acrylic resin. The blocks were cut longitudinally. Twenty specimens of each connection were evaluated. Twelve measurements of microgaps (6 on each side of specimen) were recorded under scanning electron microscopy. RESULTS: The average torsion resistance of Octatorx (203.6 ±17.4 Ncm) was significantly greater than that of the internal hexagon (146.4 ±16.1 Ncm, P<.05). For the microgap, there was a significant difference (P=.001) between the median values of Octatorx (1.19 µm) and the internal hexagon (3.80 µm). CONCLUSIONS: In this study, the new connection, Octatorx, had a smaller microgap and greater torque resistance than the internal hexagon connection.

Correlation Between Implant Stability Quotient and Percussion Sound Frequency.

OBJECTIVES: To determine the correlation between the primary implant stability quotient and the implant percussion sound frequency. MATERIALS AND METHODS: A total of 14 pigs' ribs were scanned using a dental cone beam computed tomography (CBCT) scanner to classify the bone specimens into three distinct bone density Hounsfield units (HU) value categories: D1 bone: >1250 HU; D2: 850-1250 HU; D3: <850 HU. Then, 96 implants were inserted: 32 implants in D1 bone, 32 implants in D2 bone, and 32 implants in D3 bone. The primary implant stability quotient (ISQ) was analyzed, and percussion sound was recorded using a wireless microphone connected and analyzed with frequency analysis software. RESULTS: Statistically significant positive correlations were found between the primary ISQ and the bone density HU value (r = 0.719; p < 0.001), and statistically significant positive correlations between the primary ISQ and the percussion sound frequency (r = 0.606; p < 0.001). Furthermore, significant differences in primary ISQ values and percussion sound frequency were found between D1 and D2 bone, as well as between D1 and D3 bone. However, no significant differences were found in primary ISQ values and percussion sound frequency between D2 and D3 bone. CONCLUSION: The primary ISQ value and the percussion sound frequency are positively correlated.

Effects of the cone-beam computed tomography protocol on the accuracy and image quality of root surface area measurements: An in vitro study.

Purpose: The objective of this study was to evaluate and compare the accuracy and image quality of root surface area (RSA) measurements obtained with various cone-beam computed tomography (CBCT) protocols, relative to the gold standard of micro-computed tomography (CT), in an in vitro setting. Materials and Methods: Four dry human skulls were scanned using 8 different protocols, with voxel sizes of 0.15 mm, 0.3 mm, and 0.4 mm. Three-dimensional models of the selected teeth were constructed using CBCT and micro-CT protocols, and the RSA was automatically measured by the image-processing software. The absolute difference in the percentage of the RSA (%ΔRSA) was calculated and compared across the 8 CBCT protocols using repeated-measures analysis of variance. Finally, image quality scores of the RSA measurements were computed and reported in terms of percent distribution. Results: No significant differences were observed in the %ΔRSA across the 8 protocols (P>0.05). The deviation in %ΔRSA ranged from 1.51% to 4.30%, with an increase corresponding to voxel size. As the voxel size increased, the image quality deteriorated. This decline in quality was particularly noticeable at the apical level of the root, where the distribution of poorer scores was most concentrated. Conclusion: Relative to CBCT protocols with voxel sizes of 0.15 mm and 0.3 mm, the protocols with a voxel size of 0.4 mm demonstrated inferior image quality at the apical levels. In spite of this, no significant discrepancies were observed in RSA measurements across the different CBCT protocols.

Comparative clinical study of conventional dental implant and mini dental implant-retained mandibular overdenture: A 5- to 8-Year prospective clinical outcomes in a previous randomized clinical trial.

AIM: To compare the long-term prospective clinical outcomes in a previous randomized controlled clinical trial (RCT) of 2 Mini Dental Implant (2MDI), 4 Mini Dental Implant (4MDI), and 2 Conventional Dental Implant (2CDI)-retained mandibular overdenture with follow-up between 5 to 8 years. MATERIALS AND METHODS: Thirty-seven patients formerly participated in the Comparative Clinical Study of CDI and MDI for Mandibular Overdenture were requested for examination of clinical outcomes. A total of 104 implants were placed with mean follow-up periods 6.64 ± 0.60 years. In Group 1 (2MDI) and Group 2 (4MDI), implants were placed and immediately loaded with Equator® attachments to retained mandibular overdenture. In Group 3 (2CDI), implants were placed and delayed 3 months for denture loading with ball attachment. The success rate, survival rate, clinical implant performance scale (CIP scale), peri-implant tissue status, prosthetic complication, implant stability quotient (ISQ), marginal bone level change (MBLC), and patient satisfactions were analyzed. RESULTS: After 5 to 8 years follow-up, the success rate in Groups 1, 2, and 3 were 90.91%, 93.33%, and 54.55%, respectively. The success rate in Group 3 was significantly lesser than Group 1 (p = 0.016) and Group 2 (p < 0.001). The survival rate in Groups 1, 2, and 3 was 100%, 96.67%, and 90.91%, respectively, and showed no significant differences. Mean ISQ reported no significant differences between groups. Mean MBLC were 0.57 ± 1.19 mm, 0.68 ± 0.90 mm, and 1.55 ± 1.60 mm in Groups 1, 2, and 3, respectively. Group 3 reported significantly greater mean MBLC than Group 1 (p = 0.016) and Group 2 (p = 0.011), but Groups 1 and 2 were not significantly differences. The overall patient satisfactions were reported as not significant differences between groups. CONCLUDE: Two MDI-retained mandibular overdentures with immediate loaded protocol performed had favorable clinical outcomes, cost effectiveness, and overall patient satisfactions after 5 to 8 years follow-up.

The implant position accuracy between using only surgical drill guide and surgical drill guide with implant guide in fully digital workflow: a randomized clinical trial.

BACKGROUND: To evaluate and compare accuracy in position and inclination of a single-tooth implant placement using tooth-supported surgical drill guide (SDG) and surgical drill guide with implant insertion guide (SDIG) in fully digital workflow. MATERIALS AND METHODS: Thirty partially single edentulous patients were recruited. After randomization, participants were divided into 2 groups equally. The first group underwent implant placement through SDG only, while the second group was subjected to SDIG. All procedure proceeded under a fully digital workflow as the combination of digital scanning from an intraoral scanner, 3D radiographic images from cone-beam computed tomography (CBCT), implant planning software, and a 3D manufacturing machine. A post-operative CBCT was performed to compare the deviations (7 parameters) between planned and actual implant positions. RESULTS: The mean global deviations at the shoulder and apex were 0.74 ± 0.36 and 1.29 ± 0.61 mm, respectively in the SDG group and 0.48 ± 0.22 mm and 0.71 ± 0.31 mm, respectively in the SDIG group. Likewise, the other parameters in the SDIG group showed fewer deviations than SDG for all measurements. Statistically significant differences were indicated by all parameters except for the horizontal deviation at the implant shoulder (p < .05). CONCLUSION: In single-tooth implant placement with a tooth-supported guide using a computer-assisted (static) system with the SDIG could reduce deviations of actual implant position when compared with using SDG only. Besides, guided implant surgery by fully digital workflow is a practical procedure and provides precise implant position regarding the prosthetic-driven concept.

Implant-abutment screw removal torque values between customized titanium abutment, straight titanium abutment, and hybrid zirconia abutment after a million cyclic loading: an in vitro comparative study.

PURPOSE: The aim of this study was to compare removal torque values after mechanical cyclic loading and bending moment after the static compression testing of customized titanium abutment compared with prefabricated and hybrid abutments. MATERIALS AND METHODS: The study was developed according to ISO 14801:2016. Sixty implants were divided into three groups equally: Straight titanium abutment group, Customized titanium abutment group, and Hybrid zirconia abutment group. Abutments were fabricated with zirconia restoration. Forty five implants underwent for cyclic loading. The removal torque values were measured after a fatigue test was conducted at 0 cycles (control), 50,000 cycles and 1,000,000 cycles. In the second experiment, 15 implants were divided into the same groups. Then, bending moments were investigated. RESULTS: The mean initial removal torque value was significantly higher than 50,000 cycles and 1,000,000 cycles (P < 0.001). The comparison of mean removal torque value between types of abutments was not significantly different (P > 0.05), and the bending moments of all abutments were not significantly different (P > 0.05). CONCLUSIONS: From the boundary of this in-vitro study, it could be concluded that customized titanium abutment and hybrid abutment were not significantly different in terms of removal torque values after the fatigue test. The bending moment between types of abutment were not significantly different. Thus, it could be concluded that abutment type does not significantly influence abutment stability or fracture strength.

Bone regeneration of a polymeric sponge technique-Alloplastic bone substitute materials compared with a commercial synthetic bone material (MBCP+TM technology): A histomorphometric study in porcine skull.

BACKGROUND: Polymeric sponge technique is recommended for developing the desired porosity of Biphasic calcium phosphate (BCP) which may favor bone regeneration. PURPOSE: To investigate the healing of BCP with ratio of HA30/ß-TCP70 (HA30) and HA70/ß-TCP30 (HA70) polymeric sponge preparation, compare to commercial BCP (MBCP+TM). MATERIALS AND METHODS: Materials were tested X-ray diffraction (XRD) pattern and scanning electron microscope (SEM) analysis. In eight male pigs, six calvarial defects were created in each subject. The defects were the filled with 1 cc of autogenous bone, MBCP+TM (MBCP), HA30, HA70, and left empty (negative group). The new bone formations, residual material particles and bone-to-graft contacts were analyzed at 4, 8, 12 and 16 weeks. RESULTS: Fabricated BCP showed well-distributed porosity. At 16 weeks, new bone formations were 45.26% (autogenous), 33.52% (MBCP), 24.34% (HA30), 19.43% (HA70) and 3.37% (negative). Residual material particles were 1.88% (autogenous), 17.58% (MBCP), 26.74% (HA30) and 37.03% (HA70). These values were not significant differences (Bonferroni correction <0.005). Bone-to-graft contacts were 73.68% (MBCP), which was significantly higher than 41.68% (HA30) and 14.32% (HA70; Bonferroni correction <0.017). CONCLUSIONS: Polymeric sponge technique offers well-distributed porosity. The new bone formation and residual material particles were comparable to MBCP+TM, but the bone-to-graft contact was lower than MBCP+TM.

Effect of the Location of Dental Mini-Implants on Strain Distribution under Mandibular Kennedy Class I Implant-Retained Removable Partial Dentures.

PURPOSE: To investigate the effect of minidental implant location on strain distributions transmitted to tooth abutments and dental minidental implants under mandibular distal extension removable partial denture. MATERIALS AND METHODS: A mandibular Kennedy Class I distal extension model missing teeth 35-37 and 45-47 was constructed. Six dental mini-implants were placed at positions A, B, and C, where position A was 6.5 mm distal to the abutment teeth with 5 mm between each position. Fourteen uniaxial strain gauges were bonded on the model at the region of dental mini-implant and abutment (first premolar). Four groups were designated according to the location of the mini-implants. A load of 150 N and 200 N was applied using an Instron testing machine. Loadings consisted of bilateral and unilateral loading. Comparisons of the mean microstrains among all strain gauges in all situations were analyzed. RESULTS: Variation in mini-implant locations induced local strains in different areas. Strains at the tooth abutment were significantly decreased in the group in which implants were placed mesially. Strains around the mini-implants showed different patterns when loaded with different loading conditions. The group in which implants were placed distally showed the lowest strains compared to other groups. CONCLUSION: Mesially placed mini-implants showed the lowest strain around abutment teeth, while a distally-placed mini-implants presented the lowest strain around mini-implants themselves. Under favorable biting force, mini-implant is an option to assist mandibular distal extension removable partial denture. Mesially placed mini-implants are recommended when the abutment has periodontally compromised conditions and a distally placed mini-implant when periodontal conditions are stable.

Platelet-rich fibrin to preserve alveolar bone sockets following tooth extraction: A randomized controlled trial.

BACKGROUND: Platelet-rich fibrin (PRF) can be used in the alveolar socket preservation (ARP). However, the hard tissue-regeneration property of PRF in alveolar socket preservation is still unclear. PURPOSE: To compare the new bone formation ratio between using PRF as a socket preservation material and normal wound healing, by means of histomorphometric analysis. MATERIALS AND METHODS: Thirty-three healthy volunteers were recruited and randomized into PRF and control group. Minimally traumatic extractions were performed. Eighteen patients were treated with ARP using PRF, while the rest were left to heal naturally. Bone specimens were harvested using trephine bur 2 months after the extraction process. Histomorphometric analysis of new bone formation area compared with total socket area was performed using the software Fiji Is Just Image J (version 2, GNU General Public License). RESULTS: Thirty-three volunteers were participated. Twenty-eight bone specimens were collected. The new bone formation ratio was higher in PRF group than in control group (31.33 ± 18% and 26.33 ± 19.63%, respectively). However, there was no statistically significant difference in the ratio between the PRF and control groups (P = .431). CONCLUSIONS: It may be concluded that the use of PRF in ARP does not statistically significant enhance new bone formation after tooth extraction compared to normal wound healing (P > .05).

Removal torque pattern of a combined cone and octalobule index implant-abutment connection at different cyclic loading: an in-vitro experimental study.

BACKGROUND: Despite the high survival rate of dental implants, screw loosening is frequently reported. Screw loosening can cause a misfit of the implant-abutment connection leading to peri-implantitis or abutment screw fracture. Therefore, studies about related factors and mechanism of screw loosening are needed. The aim of this study was to evaluate the decreasing pattern of removal torque values (RTVs) of a combined cone and octalobule index implant-abutment connection under different numbers of mechanical loading cycles. MATERIALS AND METHODS: The study was performed in accordance with ISO 14801:2007. Eighty-four implants with the combined cone and octalobule index implant-abutment connection (PW Plus dental implant system, PW Plus Company) were used. All abutment screws were tightened 30 N cm twice with a 10-min interval. The control group was without cyclic loading and the experimental groups underwent different numbers of loading cycles until 2,000,000 cycles. Then, the abutment screws of all samples were untightened to measure the RTVs. The data were analyzed using ANOVA and Tukey's HSD test. RESULTS: The RTVs of the control group decreased 7.78% compared to the insertion torque. All experimental groups from 50,000 to 2,000,000 cycles showed significant decreases in RTVs compared to the control group (P < 0.05). RTVs in the group of 50,000 cycles to 1,800,000 cycles did not change significantly, but there was a significant reduction of RTVs in the group of 2,000,000 cycles when compared to the group of 50,000 cycles (P < 0.05). CONCLUSIONS: According to the setting condition for the fatigue test complied to ISO 14801:2007, the RTVs of the combined cone and octalobule index implant-abutment connection reduced significantly after 50,000 cycles and did not change significantly until 2,000,000 cycles.

Comparative Study Between an Immediate Loading Protocol Using the Digital Workflow and a Conventional Protocol for Dental Implant Treatment: A Randomized Clinical Trial.

Background: The purposes of this randomized clinical trial study was to compare the immediate loading of dental implants while employing digital workflow and conventional implants in terms of the success rate, marginal bone level, and patient satisfaction. Methods: Fifty patients who had edentulous area on the mandibular premolar or molar area were included in the study. Twenty-five patients were assigned to immediate loading implant treatment using the digital technique and 25 patients were assigned to conventional loading implant treatment. In the first group, the patients were received digital impression (Cerec Omnicam, Dentsply Sirona®, York, PA, USA), designed, producing zirconia crown, and inserted on the same surgery day. The second group, after a healing period of three months, was received analog impression following conventional impression for the zirconia crown. Clinical outcome and radiographic bone level were evaluated after three, six, and 12 months. Patient satisfaction was measured at 12 months after inserting the implant. Results: There was no implants and protheses failure in both groups. The mean resonance frequency analysis values at the day of surgery were 78.26 ± 4.09 in immediate loading using the digital group (ILD) and 73.74 ± 5.14 in the conventional loading group (CL), respectively. Insertion torque values at the day of surgery were 36.60 ± 12.64 in ILD and 38.8 ± 12.19 CL, respectively. The marginal bone level in CL at three, six, and 12 months were 0.14 ± 0.28 mm, 0.18 ± 0.30 mm, and 0.17 ± 0.29 mm, respectively, while in ILD at three, six, and 12 months were 0.18 ± 0.33 mm and 0.16 ± 0.27 mm and 0.15 ± 0.31, respectively. There was no statistically significant difference between the two groups. Only one question in patient satisfaction's questionnaire was "Now, can your dental implant and crown be used well?" had been significantly different in favor to the conventional group. Conclusion: Within the limitation of this study, it may be concluded that, after one-year follow up, there were no statistically significant differences between the immediate loading of dental implants employed from the digital workflow and conventional implant treatment technique in the success rate and marginal bone level. In patient satisfaction, there was only statistic significant difference in question related to implant prosthetic function in favor of the CL group, whereas the question concerning speaking, cleansing, price, and expectation displayed no difference.

Comparison of platelet-rich fibrin and cellulose in palatal wounds after graft harvesting.

AIM: The aim of the present study was to compare patient morbidity and healing outcomes of free gingival graft (FGG) harvesting at palatal donor sites and after using platelet-rich fibrin (PRF) and oxidized regenerated cellulose (ORC). FGG harvesting leaves open palatal wounds, which heal by secondary intention. Patients might experience discomfort or pain during the first 2 weeks of healing. METHODS: Eighteen participants requiring two FGG were recruited. The test and control sites were covered with PRF membrane and ORC. The complete epithelialization of the palatal wound, the percentage of wound healing, and postoperative pain were evaluated, 1, 3, and 7 days and 2, 3, and 4 weeks after surgery. RESULTS: Similar wound size reduction at 1 week (test: 36.87%, control: 38.78%) was found. At 2 weeks, the majority of the test group (88.89%) showed complete epithelialization, whereas 66.67% of the control group had complete epithelialization (P = .228). Pain was more prevalent in the control group (27.77%) than in the test group (11.1%) on day 1. None of the participants reported any pain or discomfort at the test sites on day 3. CONCLUSIONS: PRF seems to reduce patient morbidity, but there is no difference in palatal wound healing (P > .05).

Comparative study of immediate loading on short dental implants and conventional dental implants in the posterior mandible: A randomized clinical trial.

PURPOSE: Immediate dental implant loading has been investigated with favorable results. However, short implants have not been investigated in this treatment option. This study compared the clinical outcomes and survival rates of immediately loaded short and conventional length dental implants in replacing mandibular molar teeth. MATERIALS AND METHODS: Forty-six implants (23 short dental implants and 23 conventional dental implants) in 46 patients were included in the study. Provisional computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic crowns were cemented to the abutments and immediately loaded. Several clinical parameters were recorded and statistically analyzed at 4-month- and 1-year-follow-up. RESULTS: Two short implants lost integration, and one conventional implant failed. No statistically significant difference between the two implant types was found (P = 1.00). Minor complications were recorded; three provisional crown fractures were found in the short implant group and two provisional crown fractures in the conventional implant group. There was no significant difference in implant stability quotient values for short or conventional implants between baseline (short: 73.86 ± 2.38, conventional: 75.05 ± 3.26, P = .088), 4 months after loading (short: 72.37 ± 1.35, conventional: 72.89 ± 1.87, P = .165), and 1 year after loading (short: 74.60 ± 2.03, conventional: 75.35 ± 2.66, P = .296). The mean marginal bone level loss 4 months after loading was 0.28 ± 0.29 mm for short implants and 0.25 ± 0.25 mm for conventional implants (P = .73), and at 1 year after loading was 0.33 ± 0.47 mm for short implants and 0.26 ± 0.27 mm for conventional implants (P = .554); there was no statistical difference between the two implant types. CONCLUSION: The immediate loading of short implants is comparable to conventional length implants in terms of implant survival, marginal bone level change, and implant stability quotient value.

Comparative study of stress characteristics in surrounding bone during insertion of dental implants of three different thread designs: A three-dimensional dynamic finite element study.

The objective of this study is to evaluate the stress distribution characteristics around three different dental implant designs during insertion into bone, using dynamic finite element stress analysis. Dental implant placement was simulated using finite element models. Three implants with different thread and body designs (Model 1: root form implant with three different thread shapes; Model 2: tapered implant with a double-lead thread; and Model 3: conical tapered implant with a constant buttress thread) were assigned to insert into prepared bone cavity models until completely placed. Stress and strain distributions were descriptively analyzed. The von Mises stresses within the surrounding bone were measured. At the first 4-mm depth of implant insertion, maximum stress within cortical bone for Model 3 (175 MPa) was less than the other models (180 MPa each). Stress values and concentration area were increasing whereas insertion depth increased. At full implant insertion depth, maximum stress level in Model 1 (35 MPa) within the cancellous bone was slightly greater than in Models 2 (30 MPa) and 3 (25 MPa), respectively. Generally, for all simulations, the highest stress value and the location of the stress concentration area were mostly in cortical bone. However, the stress distribution patterns during the insertion process were different between the models depending on the different designs geometry that contacted the surrounding bone. Different implant designs affect different stress generation patterns during implant insertion. A range of stress magnitude, generated in the surrounding bone, may influence bone healing around dental implants and final implant stability.

Mathematical equations for dental implant stability patterns during the osseointegration period, based on previous resonance frequency analysis studies.

BACKGROUND: Total stability of dental implant can be obtained from resonance frequency analysis (RFA) device, but without primary and secondary stability values. PURPOSE: To formulate mathematical equations for dental implant stability patterns during the osseointegration period. MATERIALS AND METHODS: An online systematically search of the literature between January 1996 and December 2017 was performed for all prospective clinical trials that measured implant stability using RFA device during the osseointegration period. Initial mathematical function with adjustable parameters were created. Then curve-fitting was performed using a computerized program to formulate mathematical equations stability patterns. RESULTS: Nine publications (24 study groups) were included in the mathematical analysis. Curve fitting with low sum of squared errors could be applied in all studies, except one. The stability has been divided into high, medium, and low stability. The curve fitting showed stability dip areas and intersection point which predict the returning of the stability to reach the primary stability. The study groups with low primary stability showed the poorest results, the high and medium stability group showed the stability pattern following the assumed primary stability pattern according to the mathematic equations. CONCLUSIONS: The model of primary and secondary stability could be predicted from the proposed equations.

Comparison of immediate-load mini dental implants and conventional-size dental implants to retain mandibular Kennedy class I removable partial dentures: A randomized clinical trial.

BACKGROUND: Complications of distal extension mandibular removable partial dentures are: loss of retention, irritation, and so forth. Dental implants have been used to support distal extension removable partial dentures. However, many patients have limited bone support in which to place conventional-size dental implants. PURPOSE: To compare the clinical outcomes of using immediate-loaded mini dental implants and immediate-loaded conventional-size dental implants, when used to retain mandibular Kennedy class I removable partial dentures. MATERIALS AND METHODS: Thirty patients were randomly divided into two groups. Mini dental implants and conventional-size dental implants were placed in participants in the first molar region on both sides. The dentures were connected immediately. Patients were recalled on 1, 3, 6, and 12 months after surgery. Digital periapical radiographs were made, and patient satisfaction was recorded. Data were analyzed by independent samples t-test and paired samples t-test (P = .05). RESULTS: Twenty eight of the implants survived (survival rate = 93.3%) in each group. Mean radiographic bone loss was 0.47 ± 0.42 and 1.03 ± 1.07 mm in groups 1 and 2, respectively. Conventional-size implants revealed significantly greater marginal bone loss than mini implants (P = .01). Patient satisfaction showed significant improvement after treatment in both groups. CONCLUSIONS: Immediate-loaded mini dental implants can be applied for retaining mandibular Kennedy class I removable partial dentures with very favorable results.

Endodontic Management of a Chronic Periapical Abscess in a Maxillary Central Incisor with an Immature Root Apex Using Platelet-Rich Fibrin: A Case Report.

Platelet-rich fibrin (PRF) has been used for several treatments in dentistry. The present study reports the clinical and radiographic outcomes of a root canal treatment of a necrotic immature maxillary central incisor using PRF. A 15-year-old female patient presented with a diagnosis of maxillary left central incisor pulp necrosis with open apex and periapical radiolucency and extraoral sinus tract. Two months after a two-visit root canal treatment using calcium hydroxide as a root canal dressing, no clinical symptoms were observed, and the previous sinus tract at the patient's nostril had completely disappeared. In the subsequent visit, the PRF was prepared and delivered into the root canal. The PRF layer was covered with collagen membrane and then sealed with white mineral trioxide aggregate. One year later, the patient remained asymptomatic. Radiological examination using cone beam computed tomography (CBCT) showed that the destructive buccal alveolar bone was completely repaired.

Effects of different numbers of mini-dental implants on alveolar ridge strain distribution under mandibular implant-retained overdentures.

PURPOSE: To investigate the strains around mini-dental implants (MDIs) and retromolar edentulous areas when using different numbers of MDIs in order to retain mandibular overdentures. MATERIALS AND METHODS: Four different prosthetic situations were fabricated on an edentulous mandibular model including a complete denture (CD), and three overdentures, retained by four, three or two MDIs in the interforaminal region with retentive attachments. A static load of 200N was applied on the posterior teeth of the dentures under bilateral or unilateral loading conditions. The strains at the mesial and distal of the MDIs and the retromolar edentulous ridges were measured using twelve strain gauges. Comparisons of the mean microstrains among all strain gauges in all situations were analyzed. RESULTS: The strain distribution determined during bilateral loading experienced a symmetrical distribution; while during unilateral loading, the recorded strains tended to change from compressive strains on the loaded side to tensile strains. Overall, the number of MDIs was found to be passively correlated to the generated compressive strain. The highest strains were recorded in the four MDIs followed by three, two MDIs retained overdenture and CD situations, respectively. The highest strain was found around the terminal MDI. CONCLUSIONS: The use of a low number of MDIs tends to produce low strain values in the retromolar denture-bearing area and around the terminal MDIs during posterior loadings. However, when using a high number of MDIs, the overdenture tends to have more stability during function.