All-on-4 concept with the use of zygoma implants for rehabilitation in the severely atrophied maxilla with a definitive immediate restoration.

This case report of a 45-year-old patient at initial presentation shows an illustration of the limitations of periodontal maintenance therapy and the subsequent implant prosthetic therapy. In close consultation with the patient, treatment strategies were adopted to maximize the preservation of prognostically questionable teeth. Eight years later, the patient had a highly atrophied maxilla that could be successfully restored with implants. This was achieved with two zygoma implants and two anterior conventional implants, which were immediately loaded according to the All-on-4 concept and immediately provided with a definitive prosthetic restoration. The case report demonstrates to the general practitioner that using zygoma implants in such constellations may offer a solution to achieve a fixed, rapid, and financially acceptable prosthetic rehabilitation.

Frozen Stored Teeth: Autogenous Dentin as an Alternative Augmentation Material in Dentistry.

Tooth Shell Technique (TST) with the use of autologous dentin has proven to be a suitable method of grafting in the context of lateral ridge augmentation. This present feasibility study aimed to retrospectively evaluate the preservation by lyophilization of processed dentin. Thus, the frozen stored processed dentin matrix (FST: 19 patients with 26 implants) was re-examined with that of processed teeth used immediately after extraction (IUT: 23 patients with 32 implants). Parameters of biological complications, horizontal hard tissue loss, osseointegration, and buccal lamella integrity were used for evaluation. For complications, the observation period was 5 months. Only one graft was lost (IUT group). In the area of minor complications, without the loss of an implant or augmentation, there were two cases of wound dehiscence and one case with inflammation and suppuration (IUT: n = 3, FST: n = 0). Osseointegration and integrity of the buccal lamella were present in all implants without exception. Statistically, there was no difference between the groups studied for the mean resorption of the crestal width and the buccal lamella. Results of this study show that prepared autologous dentin preserved with a conventional freezer had no disadvantage compared to immediately use autologous dentin in terms of complications and graft resorption in the context of TST.

Lateral Alveolar Ridge Augmentation with Autologous Dentin of Periodontally Compromised Teeth: A Retrospective Study.

Tooth shell technique (TST) using autologous dentine is possible with lateral ridge augmentation while avoiding a donor region. This study aimed to clarify whether the use of periodontally compromised teeth (PCT) leads to similar results compared to non-periodontally compromised teeth (NPCT). In this retrospective study, the dentin matrix of 41 patients (PCT: n = 19 with 29 implants; NPCT: n = 22, with 29 implants) was used for TST. All cases were re-examined. Outcome parameters were biological complications, horizontal hard tissue loss, osseointegration, and the integrity of the buccal lamella. Only in one case in the PCT group, a graft was lost. In three cases, minor complications were identified, including two cases of wound dehiscence and one case of inflammation with suppuration (PCT: n = 1, NPCT: n = 3). All implants, except the one with the severe complication, were osseointegrated and the integrity of the buccal bone lamella was preserved. Mean difference of the resorption of the crestal width and the buccal lamella did not differ statistically between the two groups. TST using PCT showed results comparable to those of NPCT in terms of complications and graft resorption. Processed dentin matrix from PCT can be used and applied with predictable results for bone grafting, utilizing TST.

How do specialist surgeons treat the atrophic tooth gap? A vignette-based study among maxillofacial and oral surgeons.

BACKGROUND: There is little information available regarding the decision-making process of clinicians, especially in the choice of therapy for a severely atrophic tooth gap. The aim of this research was to use case vignettes to determine the influence of possible factors on the decision making of maxillofacial and oral surgeons. METHODS: A total of 250 maxillofacial (MFS) and oral (OS) surgeons in southern Germany were surveyed for atrophic single- or multiple-tooth gap with the help of case vignettes. The influence of different determinants on the therapy decision was investigated. Two case vignettes were designed for this purpose: vignette 1 with determinants "patient age" and "endocarditis prophylaxis" and vignette 2 with determinants "anxiety" and "bisphosphonate therapy". Furthermore, the specialist designation was assessed for both. The options available to achieve a sufficient implant site were "bone split", "bone block", "augmentation with bone substitute material" and "bone resection". Therapy was either recommended or rejected based on principle. RESULTS: A total of 117 participants returned the questionnaire: 68 (58%) were OS and 49 (42%) MFS. "Patient age" and "patient anxiety" were not significantly associated with any therapy decision. However, required "endocarditis prophylaxis" led to significantly higher refusal rates for "bone split", "bone block" and "bone replacement material" and to higher rates of general refusal of a therapy. "Bisphosphonate therapy" was significantly associated with general refusal of therapy, but with no significant correlation with different therapy options. In vignette 1, OS refused therapy significantly more often than MFS, though there was no association with the specialist designation for other therapy modalities. In vignette 2, specialty was not significantly associated with the therapy decision. CONCLUSION: "Patient age" as well as "patient anxiety" appear to have no or little influence on the treatment decision for severely atrophic single- or multiple-tooth gap by specialist surgeons. Surgeons more often refuse treatment for patients with endocarditis prophylaxis and bisphosphonate therapy.

Evaluation of the surgical and prosthetic success of All-on-4 restorations: a retrospective cohort study of provisional vs. definitive immediate restorations.

BACKGROUND: All-on-4 concept allows an immediate restoration, which is frequently a provisional restoration (PR), and will be replaced by a definitive restoration (DR) a few months later. However, this approach involves much higher treatment efforts and costs, compared to a DR immediately after implantation. PRs were mostly incorporated in the introductory phase of the All-on-4 concept in our respective clinics. Today, PRs are only used for referred patients and bimaxillary restorations. The aim of the study was to investigate whether PRs and DRs have comparable success rates. METHODS: A total of 126 patients with 136 All-on-4 restorations supported by 544 implants were included in this retrospective cohort study. The observation period was 1 year. In 42 cases, a PR was placed initially and replaced by a DR 3 months later. In 94 cases, a DR was placed immediately. Biological, technical, and severe (loss of an implant or PR/DR) complications associated with PRs and DRs were compared. The absence of a serious complication was considered a success. RESULTS: A total of 27 patients were affected by 33 complications, 19 biological (2 PR and 17 DR) and 14 technical (6 in PR and 8 in DR) in the first 3 months. Eight patients had ten severe complications (1 PR and 9 DR). Severe complications were all implant losses. Implant survival rate was 98.2% (99.4% PR and 97.6 DR), and restoration survival rate was 94.4% (97.6% PR and 92.6% DR). Six out of the ten implant losses occurred in the posterior maxillae of male patients. After 3 months, ten complications occurred in six patients within 1 year. One of these complications was an implant loss in the posterior maxillae of a male patient. CONCLUSION: PRs and DRs showed comparable complication rates during the observation period. Only in male patients did implant losses occur more frequently in the posterior maxilla.

Retrospective Study: Lateral Ridge Augmentation Using Autogenous Dentin: Tooth-Shell Technique vs. Bone-Shell Technique.

In the literature, autogenous dentin is considered a possible alternative to bone substitute materials and autologous bone for certain indications. The aim of this proof-of-concept study was to use autogenous dentin for lateral ridge augmentation. In the present retrospective study, autogenous dentin slices were obtained from teeth and used for the reconstruction of lateral ridge defects (tooth-shell technique (TST): 28 patients (15 females, 13 males) with 34 regions and 38 implants). The bone-shell technique (BST) according to Khoury (31 patients (16 females, 15 males) with 32 regions and 41 implants) on autogenous bone served as the control. Implants were placed simultaneously in both cases. Follow-up was made 3 months after implantation. Target parameters during this period were clinical complications, horizontal hard tissue loss, osseointegration, and integrity of the buccal lamella. The prosthetic restoration with a fixed denture was carried out after 5 months. The total observation period was 5 months. A total of seven complications occurred. Of these, three implants were affected by wound dehiscences (TST: 1, BST: 2) and four by inflammations (TST: 0, BST: 4). There were no significant differences between the two groups in terms of the total number of complications. One implant with TST exhibited a horizontal hard tissue loss of 1 mm and one with BST of 0.5 mm. Other implants were not affected by hard tissue loss. There were no significant differences between the two groups. Integrity of the buccal lamella was preserved in all implants. All implants were completely osseointegrated in TST and BST. All implants could be prosthetically restored with a fixed denture 5 months after augmentation. TST showed results comparable to those of the BST. Dentin can therefore serve as an alternative material to avoid bone harvesting procedures and thus reduce postoperative discomfort of patients.

Microbiological findings in early and late implant loss: an observational clinical case-controlled study.

BACKGROUND: Implants are a predictable and well-established treatment method in dentistry. Nevertheless, looking at possible failures of dental implants, early and late loss have to be distinguished. The intent of the study was to report microbiological findings on the surface of implants with severe peri-implantitis, which had to be explanted. METHODS: 53 specimens of implants from 48 patients without severe general illnesses have been examined. The groups investigated were implants that had to be removed in the period of osseointegration (early loss, 13 patients with 14 implants) or after the healing period (late loss, 14 patients with 17 implants). The implant losses were compared with two control groups (implants with no bone loss directly after completed osseointegration, two to four months after implant placement (17 patients with 17 implants) and implants with no bone loss and prosthetic restoration for more than three years (5 patients with 5 implants)). Data about the bacteria located in the peri-implant sulcus was collected using amplification and high throughput sequencing of the 16S rRNA gene. RESULTS: The biofilm composition differed substantially between individuals. Both in early and late implant loss, Fusobacterium nucleatum and Porphyromonas gingivalis were found to be abundant. Late lost implants showed higher bacterial diversity and in addition higher abundances of Treponema, Fretibacterium, Pseudoramibacter and Desulfobulbus, while microbial communities of early loss implants were very heterogeneous and showed no significantly more abundant bacterial taxa. CONCLUSIONS: Specific peri-implant pathogens were found around implants that were lost after a primarily uneventful osseointegration. P. gingivalis and F. nucleatum frequently colonized the implant in early and late losses and could therefore be characteristic for implant loss in general. In general, early lost implants showed also lower microbial diversity than late losses. However, the microbial results were not indicative of the causes of early and late losses.

Decision-Making in Implantology-A Cross-Sectional Vignette-Based Study to Determine Clinical Treatment Routines for the Edentulous Atrophic Mandible.

This cross-sectional study aimed to investigate the influence of possible factors in the patient history on decision making in the therapy for a severely atrophied edentulous mandible. A vignette-based survey among 250 maxillofacial and oral surgeons was conducted. Determinants that could influence the therapy decision were patient age, smoking, fear of surgery, and radiotherapy in the head and neck area (the implant region is not in the direct radiation area). To achieve a suitable implant site, the options offered to the surgeons were bone split, bone block, augmentation with bone substitute material, and bone resection. There also was the option of rejecting any therapy. The response rate was 47%. Patient age, radiotherapy, and fear of surgery did not influence the approval of a therapy. Smoking was associated with a significantly lower endorsement of a treatment. Resection was preferred by a large majority to all other forms of therapy, regardless of the four determinants. Surgeons tend to refrain from bone block transplants in older patients. In summary, it can be said that, of the four determinants, only smoking influenced treatment refusal. Bone resection is the preferred therapy independent of all determinants.

Pre-implantological treatment routines for alveolar ridge atrophy - an investigation among maxillofacial and oral surgeons in southern Germany.

BACKGROUND: It is not well-known which pre-implantological procedures are preferred by maxillofacial (MFS) and oral surgeons (OS) for the narrow atrophic alveolar ridge under practice based conditions and, if different training paths in surgery lead to other pre-implantological techniques being preferred. This study aims to identify which procedures are preferred by the respective specialists in which indication. METHODS: A questionnaire was sent to a total of 300 MFS and OS in southern Germany. The questionnaire examined pre-implantological procedures (bone block, bone grafting material and/or particulate autogenous bone, titanium mesh, bone split, resection) in the edentulous severely atrophic mandible and in the severely atrophic single-tooth gap. Kendall's Tau-b test was used for statistical analyses. RESULTS: One hundred seventeen participants returned the questionnaire. 68 (58%) were OS and 49 (42%) were MFS. In the edentulous mandible, bone substitute material and resection were most preferred by both specialists. Bone blocks were statistically significantly more frequently associated with MFS and bone substitute materials with OS. Bone split was more frequently used in the atrophic single tooth gap than in the edentulous mandible. OS preferred bone blocks in the single tooth gap more often than in the edentulous mandible. MFS and OS preferred resection in the edentulous mandible significantly more frequently than in the single tooth gap. CONCLUSIONS: MFS in general prefer more invasive pre-implantological therapies with the same initial diagnosis than OS, which seems to be attributed to different training paths.

Postoperative discomfort after implant placement according to the All-on-4 concept with or without Zygoma implants: A prospective clinical study.

OBJECTIVES: The purpose of the study was to assess patients' postoperative discomfort after implantations according to the All-on-4 concept with and without using Zygoma implants. MATERIAL AND METHODS: Three treatment groups were formed for this prospective study: All-on-4 rehabilitation in the maxilla (group 1, N = 25), All-on-4 rehabilitation in the maxilla using at least two Zygoma implants (group 2, N = 25), and All-on-4 rehabilitation in the mandible (group 3, N = 20). Principal outcome parameters were postoperative pain (100 mm VAS) and perceived swelling (100 mm VAS). Also, the use of analgesics was documented. RESULTS: The worst postoperative pain of 21.3 (SD 18.9) VAS was observed in group 2, but there was no statistically significant difference between the groups (mixed ANOVA p = .791). The postoperative total intake of painkillers was significantly higher in group 2 than in the other groups (p < .001). On postoperative day 28, the mean pain scores in all groups declined to values below 5 VAS. Postoperative perceived swelling in group 2 was significantly more severe than it was in group 1 and 3 (p < .001). CONCLUSIONS: The use of Zygoma implants in All-on-4 surgical interventions had an essential effect on postoperative swelling, but less so on postoperative pain. The slightly increased, but statistically not significantly different postoperative pain in group 2 was compensated by an overall higher postoperative intake of painkillers compared to the other groups.

Lateral alveolar ridge augmentation with autogenous block grafts fixed at a distance vs resorbable poly-D-L-lactide foil fixed at a distance: 5-year results of a single-blind, randomised controlled trial.

PURPOSE: To report the 5-year outcomes of autogenous bone block grafts fixed at a distance (BBG-D) versus a resorbable poly-D-L-lactide foil fixed at a distance (SonicWeld Rx shell technique [SWST]) randomised controlled trial, for lateral alveolar ridge augmentation. MATERIALS AND METHODS: Thirty patients with a buccopalatal bone width of ≤ 3 mm were randomised into the following treatment groups: BBG-D and SWST. The implant survival, changes in bone morphology visualised in a cone beam computed tomography scan and periodontal parameters were assessed. RESULTS: Thirteen patients in the BBG-D group and seven in the SWST group could be included in the analysis. All implants that osseointegrated initially (BBG-D = 13 and SWST = 7) were functional at the 5-year re-evaluation. The buccopalatal bone width significantly (P < 0.001) decreased over time regardless of the study group. A bone loss of 0.00 mm was observed at the distal implant shoulder in the BBG-D group and 0.29 mm (SD 0.49 mm) in the SWST group (P = 0.04). The mean buccal bone loss was 2.56 mm (SD 3.65 mm) in the BBG-D group and 1.71 mm (SD 4.11 mm) in the SWST group (P = 0.64). The mean probing pocket depth was within sound limits in both groups without significant differences (P > 0.05). Bleeding on probing was low. CONCLUSIONS: Within the limitations of this study, a similar implant survival rate was observed between the BBG-D and SWST techniques during the 5-year follow-up. The buccopalatal bone width decreased over time regardless of the augmentation method used.

Impact of dental cement on the peri-implant biofilm-microbial comparison of two different cements in an in vivo observational study.

BACKGROUND: The type of cement used in cemented fixed implant-supported restorations influences formation of undetected excess cement and composition of the peri-implant biofilm. Excess cement and dysbiosis of the biofilm involve the risk of peri-implant inflammation. PURPOSE: The aim of the study was to investigate the impact of two different cements on the peri-implant biofilm and inflammation. MATERIALS AND METHODS: In an observational study, the suprastructures of 34 patients with cemented fixed implant-supported restorations were revised. In 20 patients, a methacrylate cement (Premier Implant cement [PIC]) and in 14 patients, a zinc oxide eugenol cement (Temp Bond [TB]) were used. After revision, TB was used for recementation. During revision and follow-up after 1 year, microbial samples were obtained. RESULTS: Excess cement was found in 12 (60%) of the 20 patients with PIC. Suppuration was observed in two (25%) implants with PIC without excess cement (PIC-) and in all 12 (100%) implants with PIC and excess cement (PIC+). Implants cemented with TB had neither excess cement nor suppuration. The taxonomic analysis of the microbial samples revealed an accumulation of periodontal pathogens in the PIC patients independent of the presence of excess cement. Significantly, fewer oral pathogens occurred in patients with TB compared to patients with PIC. TB was used in all cases (PIC and TB) for recementation. In the follow-up check, suppuration was not found around any of the implants with PIC-, only around one implant with PIC+ and around one implant with TB. Bacterial species associated with severe periodontal infections that were abundant in PIC- and PIC+ samples before the revision were reduced after 1 year to levels found in the TB samples. CONCLUSIONS: The revision and recementation with TB had a positive effect on the peri-implant biofilm in cases with PIC. The cementation of suprastructures on implants with TB is an alternative method to be considered.

Lateral alveolar ridge augmentation with autogenous block grafts fixed at a distance versus resorbable Poly-D-L-Lactide foil fixed at a distance: A single-blind, randomized, controlled trial.

OBJECTIVES: The aim of this study was to compare bone block grafts fixed at a distance (BBG-D) with the SonicWeld Rx shell technique (Poly-D-L-Lactide foil fixed at a distance, augmented with autogenous and deproteinized bovine bone particles (SWST)) for lateral alveolar ridge augmentation. METHODS: In this single-blinded, randomized, controlled trial, 30 patients with a bucco-palatal bone width of ≤3 mm were randomized into the treatment groups: "BBG-D" and "SWST". Bone width was measured with cone beam computed tomography (CBCT). One implant was placed at each grafted site. Frequencies of complications, bone gain and bone resorption in the CBCT were assessed as outcomes. RESULTS: Fifteen sites were augmented in each treatment group. One graft (7%) in the BBG-D group and five (33%) in the SWST group were lost (p = 0.17). In the SWST group, two implants (20%) were lost and none in the BBG-D group (p = 0.18). The rate of pooled severe complications (loss of graft and/or implant) was different (p = 0.035). Five (33%) wound dehiscences happened in the SWST group and none in the BBG-D group (p = 0.042). Seven (47%) nonsevere complications (wound dehiscence, inflammation, transient nerve injury) happened in the SWST group and one (7%) in the BBG-D group (p = 0.035). At the one-year evaluation, there were no significant differences in bone loss at the mesial, distal or buccal implant shoulder between treatment groups. CONCLUSIONS: Within the limitations of this study, the BBG-D method remains the gold standard for lateral alveolar ridge augmentation compared to the shell technique because of the lower complication rates.

Cement-associated peri-implant mucositis. A 1-year follow-up after excess cement removal on the peri-implant tissue of dental implants.

BACKGROUND: Methacrylate-based cements seem to promote peri-implant tissue inflammation even in the absence of excess cement. PURPOSE: The present study deals with the question of whether the removal of methacrylate cement from the peri-implant sulcus will lead to peri-implant tissues free of inflammation on a 1-year follow-up basis. MATERIAL AND METHODS: Implant supported suprastructures that had been in the mouth for at least 3.5 years either cemented with methacrylate (premier implant cement [PIC]) or zinc eugenol (temp bond [TB]) cement were compared. All superstructures in 33 patients with a total of 61 implants (35 with PIC and 26 with TB) were removed and excess cement, bleeding on probing (BOP), suppurationen and probing depth were documented. Excess cement found was removed, and in all cases the suprastructure was recemented with TB. Patients were followed up after 4 weeks (F1) and 1 year (F2). RESULTS: Excess cement was found around 60% of the implants with PIC. No excess cement was found around implants with TB. At the time of revision therapy, BOP was found around 100% of the implants with PIC and excess cement (PIC+), 93% around implants with PIC but no excess cement (PIC-), and around 42% of the TB-cemented implants (Chi-squared P < .01). Suppuration was observed in 86% of the PIC+ implants, in 14% of the PIC- implants and in 0% of the TB implants (Chi-squared P < .01). At the time of both F1 and F2, the inflammation parameters, that is BOP and suppuration, on implant level were significantly reduced in the PIC+ cases (McNemar's test P < .01). For PIC-, BOP was significantly reduced at both points in time (P < .05). For TB no differences were found. Probing depth at F2 had significantly decreased in all groups (t test P < .05). CONCLUSION: The removal of excess cement and recementation with TB had an anti-inflammatory effect on the peri-implant tissues after 1 year.

Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment--The Obvious Source "Ain't Necessarily So".

Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision (204)Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes (208)Pb, (207)Pb and (206)Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town.

Effect of dental cements on peri-implant microbial community: comparison of the microbial communities inhabiting the peri-implant tissue when using different luting cements.

BACKGROUND: Cementing dental restorations on implants poses the risk of undetected excess cement. Such cement remnants may favor the development of inflammation in the peri-implant tissue. The effect of excess cement on the bacterial community is not yet known. The aim of this study was to analyze the effect of two different dental cements on the composition of the microbial peri-implant community. METHODS: In a cohort of 38 patients, samples of the peri-implant tissue were taken with paper points from one implant per patient. In 15 patients, the suprastructure had been cemented with a zinc oxide-eugenol cement (Temp Bond, TB) and in 23 patients with a methacrylate cement (Premier Implant Cement, PIC). The excess cement found as well as suppuration was documented. Subgingival samples of all patients were analyzed for taxonomic composition by means of 16S amplicon sequencing. RESULTS: None of the TB-cemented implants had excess cement or suppuration. In 14 (61%) of the PIC, excess cement was found. Suppuration was detected in 33% of the PIC implants without excess cement and in 100% of the PIC implants with excess cement. The taxonomic analysis of the microbial samples revealed an accumulation of oral pathogens in the PIC patients independent of the presence of excess cement. Significantly fewer oral pathogens occurred in patients with TB compared to patients with PIC. CONCLUSION: Compared with TB, PIC favors the development of suppuration and the growth of periodontal pathogens.

Revisiting mobilisation of skeletal lead during pregnancy based on monthly sampling and cord/maternal blood lead relationships confirm placental transfer of lead.

Lead (Pb) can be released from the maternal skeleton during pregnancy and lactation and transferred to the infant. Most support for this hypothesis comes from blood Pb (PbB) studies involving limited sampling during pregnancy, the maximum usually being five samplings, including at delivery. We provide longitudinal data for PbB concentrations and Pb isotopic ratios for three cohorts of pregnant females (n = 31), two of which are based on monthly sampling and the other on quarterly sampling. We also provide data for samples collected post-partum. The data are compared with changes observed in a matched, by country and age, non-pregnant control cohort (n = 5). The monthly data illustrate the variability between subjects, which is also apparent when the data are compared on a trimester basis. Mixed model analyses showed that, in the third trimester, the mean PbB level was significantly lower for women (n = 10) who took a calcium (Ca) supplement (PbB 1.6 µg/dL) than those whose Ca intake was low (low-Ca cohort; n = 15; PbB 2.5 µg/dL) because low Ca means more mobilisation is required for homoeostasis so that more Pb was mobilised from the skeleton. For women who took the supplement, post-partum PbB levels were significantly higher than those in the other periods (2.7 vs 1.4-1.6 µg/dL). For women in the low-Ca cohort, PbB levels were higher at post-partum than in pre-pregnancy and in the first and second trimesters (3.1 vs 1.8 µg/dL), while the levels in the third trimester were higher than those in the first and second trimesters. Importantly, the increase in PbB during gestation was delayed until the third trimester in the Ca-supplemented cohort compared with the low-Ca cohort. Regression analysis showed that the changes over trimester were very similar for PbB and the (206)Pb/(204)Pb ratio providing convincing evidence for extra mobilisation of Pb from the maternal skeleton during pregnancy and lactation. Isotopic ratios in the cord blood samples were similar to those in the maternal blood samples taken prior to parturition with an R (2) 0.94 for the migrant subjects and R (2) 0.74 for Australian subjects for (206)Pb/(204)Pb ratios, supporting the concept of placental transfer of mobilised skeletal stores of Pb.

Prefabricated Versus Customized Abutments: A Retrospective Analysis of Loosening of Cement-Retained Fixed Implant-Supported Reconstructions.

PURPOSE: The aim of this retrospective follow-up study was to determine whether implant-supported reconstructions on customized computer-milled abutments will loosen less frequently than those placed on prefabricated abutments. MATERIALS AND METHODS: Suprastructures on prefabricated abutments (n = 312) were compared with those on customized computer-milled abutments (n = 96) over an observation period of 2 years. In all cases, the suprastructures had been cemented on the abutments with zinc oxide-eugenol cement (ZEC). Both groups were subdivided into single-crown restorations, fixed dental prostheses (FDPs) with two implants, and FDPs with more than two implants. The data were evaluated on the denture level. RESULTS: Of the restorations on prefabricated abutments, 8% loosened, and of those on customized abutments, 3.1% loosened. The difference was not significant. Of the single crowns on prefabricated abutments, 7.7% loosened, and of those on customized abutments, 0% loosened. The difference was significant. For the FDPs with two implants (prefabricated abutments: 9.7%; customized abutments: 10.7%; not significant) and the FDPs with more than two implants (prefabricated abutments: 0%; customized abutments: 11.1%; significance not analyzed), statistical evaluation was difficult because of the small number of cases. CONCLUSIONS: Loosening of reconstructions placed on customized abutments can be reduced for single-crown restorations. When ZEC is used, customized abutments offer a valid alternative to prefabricated abutments. The small number of cases of FDPs with two implants and FDPs with more than two implants made statistical evaluation impossible.

Retrospective analysis of loosening of cement-retained vs screw-retained fixed implant-supported reconstructions.

OBJECTIVE: The cementation of fixed dental prostheses (FDPs) on implants involves the risk of undetected excess cement. If a zinc oxide-eugenol cement (ZEC) is used as the luting material, this risk appears to be lower, as the excess cement will dissolve in the peri-implant sulcus. However, using a ZEC on a general basis conflicts with the manufacturers' classification of a ZEC as a temporary luting material. To evaluate the clinical safety of ZECs, the present study investigated whether more ZECretained reconstructions than screw-retained reconstructions loosen over time. METHOD AND MATERIALS: In a retrospective observational study, the frequency of FDP loosening was investigated. For this purpose, data from patients who had been fitted with FDPs on two or more than two posterior implants were investigated. The study compared screw-retained (n = 59) vs cement-retained (n = 40) FDPs on implants over an observation period of 3.5 years after reconstruction incorporation. All cement-retained FDPs had been cemented with a temporary ZEC. RESULTS: The prevalence of reconstruction loosening was significantly lower for cement-retained FDPs when a ZEC (10%) was used than it was for screw-retained FDPs (29%); four screw-retained FDPs and one cementretained FDP developed major complications. The survival rate of the reconstructions within the observation period was 97% for screw-retained FDPs and 100% for cement-retained FDPs (not significant). CONCLUSION: The prevalence of cementretained FDP loosening was significantly lower than that of screw-retained FDPs. Cementing FDPs on implants using a temporary cement does not necessarily lead to a higher number of loosened reconstructions. Permanent cementation with ZEC appears to be justified.

Cement-associated signs of inflammation: retrospective analysis of the effect of excess cement on peri-implant tissue.

PURPOSE: Excess cement left in the peri-implant sulcus after the placement of prosthetic restorations risks inflammation in the peri-implant tissue. While many current studies deal with the question of how to avoid undetected excess cement, relatively little is known about the clinical consequences of this complication. This study analyzed the clinical findings associated with excess cement. Further, the influence of the sojourn time of undetected excess cement in the peri-implant pocket on clinical findings was investigated. MATERIALS AND METHODS: Within the scope of a retrospective clinical follow-up, the suprastructures that were originally cemented with a methacrylate cement were revised in 93 patients (171 implants). The patients were split into two groups according to the time between placement of the prosthetic restoration and revision. Group 1 (G1) had treatment revisions within 2 years of restoration placement (71 patients with 126 implants); in group 2 (G2), treatment revisions were conducted at a later time (22 patients with 45 implants). For the purpose of statistical analysis, both groups were further analyzed based on the presence/absence of excess cement at the time of revision. RESULTS: By definition, the average time to revision in G1 was shorter than in G2 (0.71 years versus 4.07 years). There was no significant difference in the frequency of excess cement at revision between G1 (59.5%) and G2 (62.2%). The clinical findings around the implants in G1 were significantly less severe than in G2 (bleeding on probing: G1 without excess cement--17.6%, G1 with excess cement--80%, G2 without excess cement--94.1%, G2 with excess cement--100%; suppuration: G1 without excess--0%, G1 with excess cement--21.3%, G2 without excess cement--23.3%, G2 with excess cement--89.3%). After removing the excess cement, cleaning and disinfecting the implant abutment and restoration, and using a different cement, significantly fewer signs of inflammation were found at further follow-up in both groups. CONCLUSIONS: Within the limitations of this retrospective observational study, excess cement was present in a high number of cement-retained implant restorations. Signs of inflammation were present in a large proportion of implants at short- to medium-term follow-up. At the time of restoration revisions, the clinical observation of previously undetected excess cement was associated with increased prevalence of inflammation. Removal of excess cement significantly reduced the signs of inflammation.