Implantoplasty and the risk of fracture of narrow implants with advanced bone loss: A laboratory study.

OBJECTIVES: To assess the impact of implantoplasty (IP) on maximum implant failure strength of narrow diameter implants of different type/design and material, with simulated advanced bone loss. MATERIALS AND METHODS: Narrow, parallel-walled implants (3.3 mm in diameter × 10 mm long) with an internal connection of different type/design [bone level (BL), tissue level (TL)] and material [Titanium grade IV (Ti), Titanium-Zirconium alloy (TiZr)] from one specific manufacturer were used. Half of the implants were subjected to IP in their coronal 5 mm; the remaining were used as controls (seven implants per group). Dynamic loading prior to maximum load strength testing was included. RESULTS: During dynamic loading, the fracture rate of BL implants was low and independent of IP, while that of TL implants increased significantly with IP compared with controls (p = .001). Maximum implant failure strength reduction (in %) due to IP, was 1.3%-25.4%; TiZr BL implants were least affected. Implants subjected to IP compared to those without IP as well as TL implants compared to BL implants showed a significantly lower maximum implant failure strength (p < .002); implant material was not significant (p = .845). CONCLUSIONS: Based on data from implants of one specific manufacturer, IP has a significant negative impact on the fracture strength of narrow implants suffering from advanced peri-implantitis. TL implants have been more severely affected compared to BL implants and presented an increased risk for failure during normal chewing forces. In addition, this negative impact of IP on TL implants was independent of the implant material (i.e., Ti or TiZr). CLINICAL RELEVANCE: Narrow single TL implants with advanced horizontal bone loss (e.g., 5 mm), when subjected to IP, appear to have an increased fracture risk during normal function.

Does implantoplasty affect the failure strength of narrow and regular diameter implants? A laboratory study.

OBJECTIVE: To assess whether the impact of implantoplasty (IP) on the maximum implant failure strength depends on implant type/design, diameter, or material. METHODS: Fourteen implants each of different type/design [bone (BL) and tissue level (TL)], diameter [narrow (3.3 mm) and regular (4.1 mm)], and material [titanium grade IV (Ti) and titanium-zirconium alloy (TiZr)] of one company were used. Half of the implants were subjected to IP in a computerized torn. All implants were subjected to dynamic loading prior to loading until failure to simulate regular mastication. Multiple linear regression analyses were performed with maximum implant failure strength as dependent variable and IP, implant type/design, diameter, and material as predictors. RESULTS: Implants subjected to IP and TL implants showed statistically significant reduced implant failure strength irrespective of the diameter compared with implants without IP and BL implants, respectively. Implant material had a significant impact for TL implants and for regular diameter implants, with TiZr being stronger than Ti. During dynamic loading, 1 narrow Ti TL implant without IP, 4 narrow Ti TL implants subjected to IP, and 1 narrow TiZr TL implant subjected to IP were fractured. CONCLUSION: IP significantly reduced the maximum implant failure strength, irrespective implant type/design, diameter, or material, but the maximum implant failure strength of regular diameter implants and of narrow BL implants remained high. CLINICAL RELEVANCE: IP seems to have no clinically relevant impact on the majority of cases, except from those of single narrow Ti TL implants, which may have an increased risk for mechanical complications. This should be considered for peri-implantitis treatment planning (e.g., communication of potential complications to the patient), but also in the planning of implant installation (e.g., choosing TiZr instead of Ti for narrow implants).

Histology of augmented autogenous bone covered by a platelet-rich fibrin membrane or deproteinized bovine bone mineral and a collagen membrane: A pilot randomized controlled trial.

OBJECTIVES: This study aimed to evaluate histologic and histomorphometric bone characteristics with a focus on vitality after lateral alveolar ridge augmentation using an autogenous bone graft as a block covered by either a platelet-rich fibrin (PRF) membrane (test group) or a standard procedure involving coverage of the bone block with a deproteinized bovine bone mineral and a resorbable collagen membrane (control group). MATERIAL AND METHODS: A total of 27 (test = 14, control = 13) partially edentulous patients with indication for bone block augmentation before implant installation were included. For analyses, a biopsy of augmented bone was retrieved six months after bone grafting. RESULTS: Histologic evaluation of augmented bone revealed a predominance of non-vital bone toward the periosteum and few localized areas of vital bone in the center of the graft in both groups. In contrast, augmented bone toward the native bone demonstrated extensive bone remodeling in both groups. Histomorphometric analyses demonstrated a mean of 14% vital bone, 80% non-vital bone, 5% soft tissue, and 1% blood vessels in the test group. In the control group, the corresponding shares were 14% vital bone, 63% non-vital bone, 22% soft tissue, and 1% blood vessels. We observed no significant differences between the groups (p > .05). CONCLUSION: In conclusion, a comparable low bone vitality of augmented bone was observed in the PRF and in the control group. Consequently, the present study could not verify the potential beneficial effect of a PRF membrane on bone vitality of an autogenous bone graft used as a block.

Cone beam computed tomography evaluation of staged lateral ridge augmentation using platelet-rich fibrin or resorbable collagen membranes in a randomized controlled clinical trial.

OBJECTIVES: To evaluate the volumetric changes following lateral alveolar ridge augmentation using autogenous bone graft covered by either a platelet-rich fibrin membrane (test group) or an inorganic bovine bone substitute and a resorbable collagen barrier membrane (control group). MATERIAL AND METHODS: A total of 27 partially edentulous patients (test n = 14, control n = 13) with the indication for lateral bone block augmentation were included in this randomized, controlled clinical trial. Cone beam computed tomography (CBCT) examination was performed prior to grafting and 2 weeks and 6 months after grafting. The volumetric changes between the various examinations times were evaluated by planimetric measurements on two-dimensional CBCT images of the grafted regions. RESULTS: The mean bone volumetric loss in the test group was 14.7%, SD ±8.9%, while the mean bone volume loss in the control group was 17.8%, SD ±13.3%. This difference was not significant (p = 0.48). A total of ten patients were operated in the incisor and canine region with a mean bone volume loss of 23.41% SD, ±10.87%, while 17 patients were operated in the premolar region with a mean bone volume loss of 11.89% SD ±9.05%. This difference was significant (p = 0.01). CONCLUSION: The test and control group demonstrated no overall difference in volumetric bone changes of the augmented bone at the 6-month follow-up. The second major finding revealed a significantly larger amount of bone resorption in the incisor and canine region than in the premolar region of the maxilla, particularly in the control group.

Accuracy of crowns based on digital intraoral scanning compared to conventional impression-a split-mouth randomised clinical study.

OBJECTIVES: The aim of this prospective in vivo study was to evaluate the accuracy of the marginal and internal fit of crowns based on conventional impression (CI) or intraoral scan (IOS) in a randomised, split-mouth set-up. MATERIALS AND METHODS: Nineteen patients needing full coverage crowns, fitting a split-mouth design, were provided with two lithium disilicate crowns: one based on a CI and one based on an IOS. The marginal and internal accuracy of the crowns were assessed with the replica technique and clinically using a modified California Dental Association (CDA) quality evaluation system. RESULTS: At the preparation margin, the median gap was 60 µm for IOS and 78 µm for CI. For the other points, the median gap ranged from 91 to 159 µm for IOS and 109 to 181 µm for CI. The accuracy of the IOS was statistically significantly better at all point except at the cusp tip. All crowns where rated R or S at both the 6- and 12-month follow-up appointments. The results for the clinical evaluation with CDA for marginal integrity showed no statistically significant difference between the two impression methods at both the 6- and 12-month evaluations. CONCLUSIONS: Crowns based on IOS show statistically significantly better marginal and internal adaptation before cementation compared to conventional impression. However, the clinical evaluation showed similar marginal adaptation. CLINICAL RELEVANCE: Crowns based on a fully digital workflow can provide clinically acceptable marginal adaptation, comparable to crowns based on CI.

Calcium phosphate precipitation in experimental gaps between fluoride-containing fast-setting calcium silicate cement and dentin.

A novel fast-setting calcium silicate cement containing fluoride (novel-CSC) has been developed for applications in tooth crowns. The aim of this study was to assess the ability of the novel-CSC to close the experimental gaps at the dentin-cement interface. The novel-CSC was tested against Vitrebond and GC Fuji II LC. Experimental gaps of 50 or 300 µm width were created between the materials and dentin. Specimens with the 300-µm-wide gap were immersed in phosphate-buffered saline and the closed gap area was measured during 96 h. All specimens with 50 or 300 µm gap width were analyzed by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX) to assess the morphology and chemical composition of the precipitates after 96 h immersion in phosphate-buffered saline. High-resolution micro-computed tomography (µCT) was used to evaluate the integrity and continuity of the precipitiates after 96 h and 180 d. In all novel-CSC samples, precipitates closed the gap area completely after 96 h. The SEM/EDX revealed that the globular precipitates closing the gap area were mainly composed of calcium and phosphorus. After 180 d, µCT indicated thicker precipitates compared with initial precipitates only in the novel-CSC group, whereas no precipitates were observed in resin-modified glass ionomers. Novel-CSC promoted continuous precipitation of calcium phosphate, including apatite, and closed the experimental gaps.

Marginal bone level in two Danish cross-sectional population samples in 1997-1998 and 2007-2008.

OBJECTIVE: The aim of this study was to compare the marginal bone level of two randomly selected population samples from 1997/1998 and 2007/2008, with special emphasis on the role of smoking habits and gender. MATERIALS AND METHODS: Two cross-sectional randomly selected population samples [1997/1998 (N = 616) and 2007/2008 (N = 396)] were analysed with respect to the marginal bone level. The marginal bone level was measured in full-mouth intraoral radiographs. Information on smoking was gathered using questionnaires. Multiple regression analysis was used in order to adjust for correlating factors (gender, age, smoking habits and number of teeth). RESULTS: After adjusting for confounding factors, the population sample from 2007/2008 had on average a slightly, but statistically significantly, more reduced average marginal bone level (0.15 mm) than the population sample from 1997/1998. Men had more reduced marginal bone level than women (0.12 mm). Smokers in both population samples had more reduced marginal bone level than non-smokers (0.39 mm and 0.12 mm for 1997/1998; 0.65 mm and 0.16 mm for 2007/2008). CONCLUSIONS: In these populations, sampled 10 years apart, the 2007/2008 population sample had a slightly more reduced marginal bone level than the 1997/1998 population sample. Men had more reduced marginal bone level than women, and smoking is considered a major risk factor for a reduced marginal bone level.

Marginal Bone Loss after Ten Years in an Adult Danish Population: A Radiographic Study.

PURPOSE: To evaluate marginal bone loss over a 10-year period in individuals and in tooth groups in relation to age and level of marginal bone. MATERIALS AND METHODS: In 1997, 616 randomly selected individuals (mean age: 42 years, range: 21-63 years) underwent a full-mouth radiographic survey. In 2008, the survey was repeated in 362 of the same individuals (182 women and 180 men). The marginal bone level of each tooth was measured in mm from the cementoenamel junction to the marginal bone. These measurements were used to calculate marginal bone loss during the 10-year period for individuals and tooth groups in relation to age and to baseline marginal bone level, calculated as the average between measurements in 1997 and 2008 to circumvent regression towards the mean. RESULTS: The average annual marginal bone loss was 0.09 mm (SD ±â€¯0.04 mm) during the 10-year study period. The association between marginal bone loss and baseline marginal bone level was more pronounced in the youngest age group, compared to the other age groups. Molars displayed the most severe bone loss during the study period. CONCLUSION: Marginal bone loss over a 10-year period is associated with age and baseline marginal bone level. Younger individuals with a reduced marginal bone level were at higher risk for further bone loss. Molars lose marginal bone more rapidly than other tooth groups.

Comparison of radiographic and histological assessment of peri-implant bone around oral implants.

OBJECTIVES: The aim of this study was to compare the radiographic bone mineral density and the histological assessment of relative volume density of bone and bone-to-implant contact (BIC) of single implants placed in the posterior mandible of monkeys. MATERIALS AND METHODS: Five mature, male cynomolgus monkeys (Macaca fascicularis) with a total of 20 implants inserted 3-6 months previously were available for investigation. Digital intra-oral radiographs were obtained with two different sensors and one phosphor plate system. The marginal bone level was measured on both sides of the implant on digital radiographs. Furthermore, bone density was evaluated using histogram analysis of the grey shades in a distance of 1 mm from the implant surface. The radiographic assessments were compared to histomorphometric analyses. RESULTS: The marginal bone level, the distance from the margin of the implant to the most coronal bone in direct contact with the implant evaluated histologically, was on average 1.4 mm, whereas this distance was significantly shorter (0.3 mm) on the digital radiographs. Still, a statistical significant correlation between the two bone level measurements was observed. The average radiographic bone density evaluated with the three different systems varied considerably. The histologic bone density was statistically significantly lower than the radiographic bone density measured with all the three techniques for acquiring digital radiographic images. Furthermore, the histologic bone density was statistically significantly correlated with the radiographic bone density only when measured with one of the sensors. On the other hand, the histologic BIC was statistically significantly correlated with the radiographic bone density obtained with all three techniques for acquiring digital radiographic images. CONCLUSIONS: The distance from the margin of the implant to the most coronal bone in direct contact with the implant showed lower values on digital intra-oral radiographs than histologically. Furthermore, the bone density assessed on intra-oral radiographs reflected to some extend the amount of bone at or near the implant surfaces evaluated histologically.

Factors influencing severity of peri-implantitis.

OBJECTIVES: To retrospectively assess the influence of potential risk factors, primarily smoking and a prior history of periodontitis, on the severity of peri-implantitis in patients referred for treatment of peri-implantitis. MATERIALS AND METHODS: Among 98 patients referred for treatment of peri-implantitis, 34 patients fulfilled the inclusion criteria: one or several implants with peri-implant marginal bone loss ≥2 mm concomitant with bleeding and/or pus on probing. Information about health status, smoking habits, reason for tooth loss, and performed implant treatment were obtained from the patient charts and interviews. Moreover, a detailed extra- and intraoral examination was performed, including intraoral radiographs of all implants. Risk factors were evaluated by a two-way anova at patient level. RESULTS: Smoking and a prior history of periodontitis were significant risk factors for increased severity of peri-implantitis. Furthermore, the presence of both smoking and a prior history of periodontitis did not further increase the severity of peri-implantitis, as compared to either of these two factors alone. Poor marginal fit of the suprastructure and extensive gingival imitations on implant-supported fixed full prostheses may also be potential risk factors. CONCLUSIONS: The study indicated that smoking and a prior history of periodontitis were important risk factors for increased severity of peri-implantitis, while concomitant presence of these two risk factors did not further increase the severity of peri-implantitis, as compared to either of these two risk factors alone. Therefore, early diagnosis and adequate treatment of peri-implantitis are important in patients with a prior history of periodontitis and in smokers to minimize the risk of advanced peri-implantitis in conjunction with focus on known risk factors, including meticulous infection control before implant treatment and a systematic maintenance care program.

Papilla dimension and soft tissue level after early vs. delayed placement of single-tooth implants: 10-year results from a randomized controlled clinical trial.

AIM: To present the10-year esthetic outcome data for single-tooth implants placed early or delayed after tooth extraction. MATERIAL AND METHODS: Forty-four patients randomly allocated to two equal size groups were treated with a single-tooth implant approximately 10 days (Ea; N = 22), or 3 months (De; N = 22) after tooth extraction. Healing abutments were mounted after 3 months of submerged healing, and metal-ceramic crowns cemented after one additional month. Presence of buccal bone defects was registered at the second-stage surgery. Patients attended control visits 1 week and 1-1.5 years after mounting of the crown and 5 and 10 years after implant placement. Marginal bone level at the implant and the adjacent teeth as well as the distance between the implant and the teeth were measured in standardized periapical radiographs. The papilla dimension and clinical crown height (CCH) were assessed on clinical photographs by an experienced prosthodontist. RESULTS: Two Ea and one De implants failed to osseointegrate. Twenty-eight patients (13 Ea and 15 De) who attended all four control visits were included in the data analysis. Complete papilla fill interproximally was achieved in one-third of the cases and an appropriate clinical crown height in <60% after 10 years. Although not statistically significant, early-placed implants tended to be superior to delayed-placed implants regarding soft tissue appearance just after crown delivery and after 10 years. An improvement in papilla dimensions was seen during the follow-up period for both groups while the CCH was unchanged. The implant region (anterior vs. posterior) did not significantly influence the papilla or CCH scores while younger patients (<50 years of age) received significantly better papilla scores than older patients (≥ 50 years). An apically located bone level at the tooth neighboring the implant influenced negatively the papilla dimension. In contrast, the presence of a bone defect buccally to the implant at second-stage surgery did not have a negative impact on the CCH 10 years after implant placement. CONCLUSION: Early placement of single-tooth implants after tooth extraction performed equally to delayed placement in regard to the esthetic outcome of the soft tissues after 10 years in function.

The patient undergoing implant therapy. Summary and consensus statements. The 4th EAO Consensus Conference 2015.

INTRODUCTION: The assignment for this working group was to update the existing knowledge regarding factors considered being of special relevance for the patient undergoing implant therapy. This included areas where conflicting opinions exists since long or recently has been expressed, like the role of antibiotic prophylaxis in dental implant surgery and peri-implantitis. Also areas with growing interest and concern such as patient-reported outcome measures (PROMs) and health-economy was included in this review. MATERIALS AND METHODS: The literature in the respective areas of interest (antibiotic prophylaxis, peri-implantitis, patient-reported outcome measurements and health-economic aspects) was searched using different strategies for the different papers. Search strategies ranged from a complex systematic review to systematic- and narrative reviews, depending on subject and available literature. All collected material was critically reviewed. Four manuscripts were subsequently presented for group analysis and discussion and plenum discussions and concensus approval. The selected areas were considered to be of key importance and relevance for the patient undergoing implant therapy. RESULTS: The results and conclusions of the review process are presented in the respective papers. The group's conclusions, identified knowledge gaps, directions for future research and concensus statements are presented in this article. The following reviews were available for group discussions and the foundation for subsequent plenary sessions: Lund B, Hultin M, Tranaeus S, Naimi-Akbar A, Klinge B. (2015) Perioperative antibiotics in conjunction with dental implant placement. A complex systematic review. Renvert S & Quirynen M. (2015) Risk indicators for peri-implantitis. A narrative review. De Bruyn H, Raes S, Matthys C, Cosyn J. (2015) The current use of patient centered/reported outcomes in implant dentistry. A systematic review. Beikler T & Flemmig T.F. (2015) Economic evaluation of implant-supported prostheses. A narrative review.

Histologic and histomorphometric evaluation of peri-implant bone of immediate or delayed occlusal-loaded non-splinted implants in the posterior mandible--an experimental study in monkeys.

OBJECTIVES: The primary aim of this study was to compare the bone reaction around immediate-loaded non-splinted single implants vs. delayed loaded non-splinted single implants placed in healed ridges in the posterior mandible. MATERIALS AND METHODS: Six adult Macaca Fascicularis monkeys were used in this study. The first and second premolars and the first molar were extracted in both sides of the mandible. After 3 months of healing, four implants (Replace Select Tapered; Nobel Biocare, Gothenburg, Sweden) with a moderately rough surface (TiUnite, Nobel Biocare) were placed in the edentulous areas of each monkey, two in each side. The implants had a length of 10 mm and a diameter of 3.5 mm. Four groups of varying time and occlusal loading aspects were created: (i) control group: implant placed non-loaded for 3 months; (ii) immediate loaded: implant placed and loaded immediately for 3 months; (iii) immediate loaded: implant placed and loaded immediately for 6 months; and (iv) delayed loaded: implant placed submerged for 3 months and then loaded for 3 months. At the loaded implants, after a second stage surgery, a composite crown was made directly on an abutment mounted on the implant reinsuring simultaneous occlusal contact on the implant crown and the neighboring teeth. After euthanization of the animals, histologic specimens were quantified in the light microscope. RESULTS: All implants were clinically, radiographically, and histologically osseointegrated at the time of euthanization and with only mild signs of inflammation in the peri-implant mucosa. The histologic marginal bone level was located on average 1.14-1.74 mm apical to the margin of the implants in the various groups. The average bone-to-implant contact (BIC) varied between 55% and 65% and the average bone density (i.e., the proportion of mineralized bone tissue from the implant surface and to a distance of 1 mm lateral to the implant) varied between 30.6% and 34.2%. No statistical significant differences between groups were observed in the above-stated histomorphometric parameters. CONCLUSIONS: Similar histologic and histomorphometric findings were observed in immediately and delayed loaded non-splinted implants placed in the posterior mandible of macaque monkeys.

Patient satisfaction and esthetic outcome after immediate placement and provisionalization of single-tooth implants involving a definitive individual abutment.

OBJECTIVES: To assess patient satisfaction and esthetic outcome after immediate placement and provisionalization of single-tooth implants involving a definitive individual abutment and a provisional crown followed by later placement of a definitive crown. MATERIALS AND METHODS: In private practice, a single-tooth implant was placed immediately after tooth extraction in the esthetic zone of 54 patients. A definitive individual abutment and a provisional crown were mounted in the same visit. The definitive crown was placed after a mean period of 7 months. After a mean follow-up period of 33 months, the subjective and professional evaluation of the total implant treatment, peri-implant soft tissues, and implant crown were assessed on a 10-cm visual analog scale (VAS). The professional esthetic treatment outcome was also evaluated using pink esthetic score (PES), white esthetic score (WES), and total score of PES/WES. RESULTS: The evaluation of total implant treatment, peri-implant soft tissues, and implant crown demonstrated a significantly higher subjective than professional score for all 3 parameters (P < 0.001), for example, for the overall treatment, the mean scores were 9.4 and 7.0, respectively. A significant positive correlation was revealed between the professional VAS scores and the PESs and WESs. CONCLUSIONS: Immediate placement and provisionalization of single-tooth implants involving a definitive individual abutment and provisional crown followed by later placement of a definitive crown demonstrated high subjective and professional satisfaction. Generally, the professionals seem to be more critical than the patients. A strong correlation was observed between the professional VAS scores and the PES and WES scoring systems.

Immediate placement and provisionalization of single-tooth implants involving a definitive individual abutment: a clinical and radiographic retrospective study.

AIM: To assess with a mean follow-up period of 33 months (median: 31 month, range: 11-89 month) the treatment outcome after immediate placement and provisionalization of single-tooth oral implants involving a definitive individual abutment and a provisional crown followed by later placement of a definitive crown. MATERIALS AND METHODS: 68 patients with 68 single-tooth implants in the esthetic zone were consecutively treated; 55 of these patients were included in the study. The treatment involved tooth extraction, implant placement, placement of a definitive individual abutment, and a provisional crown in the same visit in private practice. The definitive crown was placed after a mean period of 7 months. The primary outcome measures included implant survival, definitive implant crown survival, and overall treatment survival. The secondary outcome measures included probing depth, bleeding on probing, peri-implant marginal bone level, marginal bone level of the neighboring tooth surfaces, biological complications, and technical complications. RESULTS: Of the inserted implants 98% survived and of the definitive crowns mounted a survival of 100% was observed. Consequently, the overall treatment survival was 98%. The mean probing depth was 2.9 mm at implant level and 63% of the implants were characterized by no bleeding on probing. The mean peri-implant marginal bone level was 2 mm. A significant mean peri-implant marginal bone level gain of 0.5 mm was observed from implant placement to the follow-up (95% CI: 0.07-0.89 mm, P = 0.022). No significant changes of the marginal bone level at the neighboring tooth surfaces were seen. Four episodes of peri-implant inflammation were identified in three patients, while 46 incidents of loosening of the provisional crown occurred in 33 patients. One abutment screw loosened before placement of the definitive crown. Finally, loosening of four definitive crowns occurred in four patients. CONCLUSIONS: Immediate placement and provisionalization of single-tooth oral implants involving a definitive individual abutment and a provisional crown followed by later placement of a definitive crown were characterized by high survival of the implant crowns and implants as well as healthy peri-implant tissues, after a mean follow-up period of 33 months. Loss of retention of the provisional crown occurred frequently.

Correspondence between conventional and digitised radiographs for assessment of marginal bone.

PURPOSE: To compare reproducibility of marginal bone measurements in conventional film and digitised radiographs and to assess whether variations in reproducibility occurred in measurements taken in a longitudinal, epidemiological survey. MATERIALS AND METHODS: Triplicate measurements of the marginal bone level and of remaining bone were obtained from film and digitised full-mouth radiographic surveys from 20 individuals who were examined three times at five-year intervals in a longitudinal study design. The digitalisation of the films was conducted by scanning the film with a flatbed scanner. The standard deviation (SD) of the triplicate measurements served as the statistic for reproducibility. The time spent for recording one radiographic survey, which consisted of 14 periapicals and 2 bitewings, was documented. RESULTS: Statistically significant differences existed in the reproducibility of marginal bone level measurements obtained at the first examination and the two subsequent examinations both for film and digitised radiographs (P < 0.05). The difference in marginal bone level measurements (film vs digitised) was 0.16 mm (SD = 0.45 mm). Similarly, the overall difference in measurements of the remaining bone was 0.12 mm (SD = 0.61 mm). Recording of a digitised survey lasted on average 5 min (SD = 1.5 min), while the recording of a film survey lasted on average 14 min (SD = 1 min). CONCLUSIONS: Digitising film is an acceptable method for the purpose of assessing the marginal bone level and will save time in longitudinal, epidemiological studies.

Prediction of future marginal bone level: a radiographic study.

AIM: The aim of the study was to predict the marginal bone level at a 5-year follow-up based on the information available from an initial radiographic examination and to evaluate the precision of the prediction by comparing the predicted bone levels with those actually observed at the follow-up. MATERIALS AND METHODS: In 1997, 616 randomly selected dentate individuals underwent a full-mouth radiographic survey. In 2003, 473 of those individuals (77%) participated in a second radiographic examination. Marginal bone level, caries lesions, fillings, crowns, root fillings and periapical status were recorded on all teeth. On the basis of data available from the first examination, a linear mixed model regression analysis with the tooth as the unit of analysis was used to predict the marginal bone level 5 years later. RESULTS: Number of teeth, smoking, and also presence of apical periodontitis and crowns were associated with bone loss and could be used as predictors of future marginal bone level. CONCLUSION: The analysis of all teeth showed that the number of tooth- and person-specific factors at the first examination influenced the prediction of the marginal bone level at the 5-year follow-up examination. However, the performance of the combined prediction model was less satisfactory.

Marginal and internal fit of crowns based on additive or subtractive manufacturing.

OBJECTIVE: To assess the marginal and internal fit of crowns manufactured by additive and subtractive manufacturing technique. MATERIALS AND METHODS: Twenty extracted teeth prepared for complete coverage crowns were scanned with an intra-oral scanner (Omnicam, DentsplySirona). For the subtractive manufacturing (SM) group, ten crowns were manufactured in a hybrid resin block (Vita Enamic, Vita Zahnfabrik). For the additive manufacturing (AM) group, the crowns were manufactured in a hybrid resin material (NextDent C&B, 3D systems). The design parameters were identical for the two groups. The marginal and internal fit (determined at the axial wall, the cusp tip and occlusally) was assessed before cementation with the replica technique and after cementation under stereomicroscope after sectioning of the crowned teeth. RESULTS: For the SM group, the marginal fit was 91 µm (±28 µm) before cementation and 85 µm (±18 µm) after cementation. In the AM group, the marginal fit was 75 µm (±29 µm) before cementation and 71 µm (±18 µm) after cementation. The differences were not statistically significant. As regards the internal fit, the fit at the axial wall was statistically significantly better in the SM group than in the AM group (p=.009 before cementation and .03 after cementation). Occlusally the fit in the AM group was significantly better than in the SM group after cementation (p<.001). CONCLUSION: Within the limitations of the current study, the marginal fit of additively manufactured crowns is comparable to crowns manufactured with chair-side subtractive technique and within the clinically acceptable range. As regards the internal fit no one technique was consistently superior.

A clinical and radiographic study of implants placed in autogenous bone grafts covered by either a platelet-rich fibrin membrane or deproteinised bovine bone mineral and a collagen membrane: a pilot randomised controlled clinical trial with a 2-year follow-up.

PURPOSE: To compare the survival and clinical performance of implants placed in sites previously augmented with autogenous bone grafts covered by either a platelet-rich fibrin (PRF) membrane (PRF group) or a standard procedure (gold standard) involving coverage of the autogenous bone graft with deproteinised bovine bone mineral and a resorbable collagen membrane (control group). METHODS: A total of 27 partially edentulous patients (test n = 14, control n = 13) with indication for staged lateral bone block augmentation and dental implant placement were included. Twenty-four months after crown placement (range: 14-32 months), patients were recalled for a final clinical and radiographic follow-up. Outcome measures were implant survival, implant crown survival, clinical parameters of the implant, peri-implant marginal bone level, marginal bone level of adjacent tooth surfaces, biological and technical complications and patient-related outcome measures. RESULTS: Two implants were lost in the control group (85% survival rate); none were lost in the PRF group (100% survival rate). None of the 26 initially placed implant crowns were lost, but one implant and therefore one implant crown were lost after 20 months. Consequently, the definitive implant crown survival was 92% (95% confidence interval (CI): 73-110%) in the control group and 100% in the PRF group. No statistical difference in implant survival rate (p = 0.13) or implant crown survival was seen between the groups (p = 0.28). The mean marginal bone level at the follow-up was 0.26 mm (95% CI: 0.01-0.50 mm) in the PRF group and 0.68 mm (95% CI: 0.41-0.96 mm) in the control group. The difference between the groups was - 0.43 mm (95% CI: - 0.80 to - 0.05 mm, p = 0.03), which was statistically significant (p = 0.03). Both groups demonstrated similar healthy peri-implant soft tissue values at the final follow-up. CONCLUSION: Although the current study is based on a small sample of participants, the findings suggest that the methodology of the PRF and the control group approach can both be used for bone augmentation with a similar outcome. A significant, but clinically irrelevant, higher peri-implant marginal bone level was registered in the PRF group than in the control group. Patients in both groups were highly satisfied with the treatment. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04350749 . Registered 17 April 2020. Retrospectively registered.

Prevalence of Aggregatibacter actinomycetemcomitans and Periodontal Findings among 14 to 15-Year Old Danish Adolescents: A Descriptive Cross-Sectional Study.

Aggregatibacter actinomycetemcomitans (Aa) is a keystone pathogen associated with periodontitis in adolescents. The knowledge on the prevalence of Aa and periodontitis among adolescents in Northern Europe is sparse. A total of 525 14- to 15-year-old adolescents from the municipality of Aarhus, Denmark, underwent a full-mouth clinical examination. Plaque score (PS), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment loss (CAL) were recorded. Subgingival plaque samples (SPS) and stimulated saliva samples (SSS) were collected and analyzed for the presence of JP2 and non-JP2 genotypes of Aa using real-time PCR. A total of 70 (13.3%) individuals were positive for Aa, with 17 found in SPS, 19 in SSS, and 35 in both. The highly leukotoxic JP2 genotype of Aa was not detected. The individuals positive for Aa in both SPS and SSS had poorer periodontal outcomes (PPD and CAL) than individuals without Aa and individuals carrying Aa in either SPS or SSS only. In conclusion, 13% of 14- to 15-year-old Danish adolescents were positive for Aa, and the presence of Aa in both SPS and SSS was associated with poorer periodontal outcomes.