Melbourne Dental School - Research Publications
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ItemThe relationship between facial bone wall defects and dimensional alterations of the ridge following flapless tooth extraction in the anterior maxilla(WILEY, 2017-08)PURPOSE: To evaluate the relationship between defects of the facial socket wall at extraction and dimensional changes 8 weeks later in maxillary central and lateral incisor sockets. MATERIALS AND METHODS: A total of 34 consecutive patients requiring single tooth implants in the anterior maxilla (27 central and 7 lateral incisors) were evaluated. Orofacial external ridge, bone dimensions and the location of the socket bone crest were measured at extraction and again 8.5 ± 2.91 weeks later. The status of the facial bone wall was recorded at the same time points. RESULTS: At extraction, 16 of 34 sites (47%) had intact facial bone. There were fenestration defects at 9 of 34 sites (26.5%) and dehiscence defects at 9 of 34 sites (26.5%). A significant reduction (P < 0.001) in the external orofacial ridge dimension occurred (mesial 1.4 ± 1.30 mm or 12.1%, facial 2.5 ± 1.46 mm or 22.2%, distal 1.1 ± 0.83 mm or 10.5%), with greatest change at dehiscence (3.3 ± 1.80 mm or 28.4%) and fenestration sites (2.8 ± 1.40 mm or 24.9%). A significant reduction in orofacial bone dimension occurred (mesial 0.8 ± 0.80 mm or 9.3%, P < 0.001; facial 1.2 ± 1.03 mm or 18.3%, P < 0.001; distal 0.4 ± 0.65 mm or 5.5%, P < 0.01). Vertical resorption of the bone crest was most marked at the mid-facial aspect (1.4 ± 1.94 mm, P < 0.001). Initial fenestration defect sites demonstrated the greatest vertical dimensional change (2.9 ± 2.67 mm; P = 0.008). Of 16 sites with initially intact facial bone, 9 sites (56.3%) developed dehiscence defects after 8 weeks. Of the 9 initial sites with fenestration defects, 5 (55.6%) turned into dehiscence defects. All 9 sites with initial dehiscence defects healed with persistence of the dehiscence. CONCLUSIONS: Eight weeks after flapless extraction of maxillary central and lateral incisors, a reduction in the orofacial dimensions of the ridge was observed due to resorption of the facial bone of the socket. Tooth type (maxillary central incisor) and thin tissue phenotype significantly influenced the outcomes. The dimensional alterations were most pronounced at sites that initially had fenestration and dehiscence defects of the facial bone.
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ItemThe influence of deproteinised bovine bone mineral on dimensional changes in the maxillary second incisor socket(WILEY, 2019-07)OBJECTIVES: To investigate the dimensional changes following the extraction of maxillary second incisors and to evaluate the influence of deproteinised bovine bone mineral on the healing outcomes. MATERIALS AND METHODS: The second maxillary incisors in nine dogs were extracted bilaterally in a minimally traumatic manner. Deproteinised bovine bone mineral with collagen (DBBMC) and a collagen matrix (CM) was placed in one socket with the contralateral socket left to heal naturally. After 3 months of healing, the dogs were sacrificed and the pre-maxilla resected. Cone beam computerised tomography scans (CBCTs) were obtained and the specimens prepared for histological preparation and analysis. Surface scans of study models taken pre- and post-extraction were digitally subtracted to analyse volumetric changes. RESULTS: All dogs healed uneventfully without any complications. No inflammation was seen, and DBBMC was well integrated into a network of mineralised tissues, bone marrow and connective tissue. The horizontal width of the buccal crest was found to be significantly greater in grafted sockets, but the vertical height to be similar. No significant difference was seen in regard to volumetric changes in sockets over 3 months post-extraction. CONCLUSION: Maxillary second incisor sockets of dogs grafted with DBBMC post-extraction had significantly greater horizontal width at the ridge crest compared with ungrafted sockets. Volumetric analysis revealed no significant difference between grafted and non-grafted sockets, suggesting possible soft tissue thickening post-extraction to counteract osseous resorption.
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ItemAlveolar ridge preservation and early implant placement at maxillary central incisor sites: A prospective case series study(WILEY, 2020-09)PURPOSE: To assess whether alveolar ridge preservation (ARP) with 90% deproteinized bovine bone mineral in a 10% collagen matrix (DBBMC) and resorbable type I/III porcine collagen matrix (CM) maintains sufficient bone volume for early implant placement 8-10 weeks after extraction of maxillary central incisors. MATERIALS AND METHODS: In this case series study of 10 consecutively enrolled patients, sockets of maxillary single central incisors requiring extraction and early implant placement were grafted with DBBMC/CM. Ridge dimensions were measured pre-extraction and just prior to implant placement. RESULTS: Alveolar ridge preservation maintained sufficient bone volume for implants to be placed in all sites. Compared to pre-extraction, there was a significant reduction in the orofacial dimensions of the ridge (1.4 ± 1.07 mm; 13.2% reduction) and bone (0.7 ± 0.67 mm; 9.3%) at the coronal midfacial region. A significant reduction in apicocoronal height of the crestal bone at midfacial (1.2 ± 0.78 mm) and palatal aspects was observed. On CBCT, a statistically significant reduction in alveolar ridge area occurred (10.9 ± 13.42 mm2 ; 12.2% reduction). To optimize aesthetic outcomes, 9/10 sites required additional low volume grafting at the coronal region, whereas one site required more extensive grafting due to a facial bone dehiscence. At 1-year, the implant survival rate was 100% and median Pink Esthetic Score (PES) was 10 (range 9-13). CONCLUSIONS: ARP using DBBMC/CM maintains sufficient bone volume for early implant placement 8.9 ± 0.97 weeks later, with a 100% survival rate 1 year after restoration.
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ItemPrimary stability and healing outcomes of apically tapered and straight implants placed into fresh extraction sockets. A pre-clinical in vivo study(WILEY, 2020-08)OBJECTIVES: To compare the stability of apically tapered and straight (non-tapered cylindrical) implants at the time of immediate placement and to histologically evaluate the healing outcomes after 6 weeks. MATERIALS AND METHODS: The second maxillary incisors were extracted bilaterally in nine dogs. After randomization, apically tapered and straight implants with a 3.3 mm shoulder diameter were inserted into the extraction sockets. The implant stability quotient (ISQ) of the implants was recorded after placement. Peri-implant defects on the buccal aspect were filled with deproteinized bovine bone mineral and covered with resorbable type I/III porcine collagen matrix. After 6 weeks of healing, sections were prepared for histological and morphometric analysis. RESULTS: All implant sites healed uneventfully. The apically tapered implants had significantly higher ISQ values compared to straight implants at placement (p = .009). The histomorphometric outcomes 6 weeks following implant placement in both experimental groups were similar, except in the apico-palatal region. Apically tapered implants demonstrated significantly less percentage bone-to-implant contact (p = .035) in the apico-palatal region. At both implant types, substantial corono-apical resorption of the buccal bone wall was noted in the coronal 2 mm of the implant. CONCLUSION: Apically tapered implants had significantly higher ISQ values at immediate placement compared to straight implants. The healing outcomes and remodelling of the buccal bone wall were similar for both implant designs. In the apico-palatal region, there was less %BIC at the implant surface at apically tapered implants compared to straight implants.
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ItemEarly implant placement in ridge preserved extraction sockets: A pre-clinical in vivo study(WILEY, 2021-06)OBJECTIVES: The aim was to analyse the outcomes of early implant placement after 6 and 12 weeks of healing in ridge preserved sites in a canine model. MATERIALS AND METHODS: Implants were placed in second maxillary incisors sites in 9 dogs 6 weeks after grafting of the sockets with 90% deproteinized bovine bone mineral in 10% collagen matrix (DBBMC) and closure with resorbable type I/III porcine collagen matrix (PCM). The implants were randomly assigned to 6 (T6) and 12 (T12) weeks of healing. RESULTS: The percentage of bone-to-implant contact (%BIC), old bone, new bone and residual DBBMC was similar between T6 and T12. In relation to the implant shoulder (IS), the original bone crest (IS-ROB) was more apical on the buccal than the palatal side. The regenerated bone crest (IS-C) and IS-ROB were similar between groups. However, the distance from IS to first bone-to implant contact (IS-fBIC) was significantly less in T12 compared with T6 (p = .022; Wilcoxon signed-rank test). The bucco-palatal ridge dimensions between T6 and T12 were similar. CONCLUSIONS: This study confirms that implants can successfully be placed early in ridge preserved maxillary second incisor sites and are osseointegrated by 6 weeks. There were significantly lower IS-fBIC values at 12 weeks than at 6 weeks on the buccal aspect. The original buccal bone crest underwent greater corono-apical resorption than the palatal crest. The %BIC, relative proportions of mineralized tissues and dimensions of the alveolar ridge demonstrated stability between 6 and 12 weeks of healing.