| Background:In clinical practice,due to physiological reconstruction after tooth extraction,the remaining alveolar ridge will be absorbed to varying degrees,resulting in a decrease in bone height and width.Especially when there is a serious bone defect in the bone wall of the extraction socket,there will be insufficient soft and hard tissue after the extraction of the bone after a few months,which will cause the posterior area to be unable to place the implant in the correct three-dimensional position,and even need to do bone augmentation simultaneously or in advance.It will increase the difficulty of the operation and the discomfort of the patient,and extend the treatment time.Alveolar ridge preservation is a technique that uses biological materials to fill and cover the alveolar socket to maintain or increase the contour of the alveolar ridge after extraction.It has been recognized as an effective technique for reducing the bone resorption of the alveolar ridge after extraction.The surgical procedure can promote the formation of new bone in the alveolar socket and reduce the rate of bone grafting during the same period of implant placement.At present,the research on the preservation of alveolar ridge is often limited to the extraction sockets of the anterior teeth with intact or a few defects,and the research on the ridge preservation at posterior extraction sites with severe bone deficiency is rare.Objective:This study aimed to evaluate the clinical effect of Alveolar Ridge Preservation/Augmentation at Posterior Extraction Sites with Severe Bone Loss(More than 50% of one or more bone height resorption)using Bio-Oss collagen,PRF and resorbable collagen membrane.Methods:According to the inclusion and exclusion criteria,a total of 31 patients completed the follow-up,including 15 males and 16 females.There were16 people in the experimental group,including 10 males and 6 females,with an average age of 51.8±11.1 years old;15 people in the control group,including 5 males and 10 females,with an average age of 47.9±14.3 years old.The experimental group used DBBM-c,absorbable collagen membrane and PRF membrane for preservation of the alveolar ridge;the control group was left healing naturally after extraction without any treatment.Observe the following indicators:1)Clinical index: before tooth extraction,measuring probing depth(PD),bleeding index(BI),gingival index(GI),gingival phenotype(BT)before extraction;measuring changes of buccal keratinized tissue width(KTW)before extraction and 4 months after alveolar ridge preservation2)Simultaneous bone augmentation rate and implant torque: 4 months after the alveolar ridge preservation,implants were placed,and the simultaneous bone augmentation rate and implant torque during the implantation period were recorded.3)Radiographic index: CBCT was taken before tooth extraction and 4months after the alveolar ridge preservation.The bone wall thickness(BBT)at different sites of the extraction socket,the changes bone height(BH)at different sites,the ridge width(RW)changes and the socket volume(SV)changes were recorded.Mimics 20.0 software was used for linear and three-dimensional analysis;SPSS 26.0 software was used for statistical analysis.4)Patient-related index: The visual analog scale(VAS)was used to record the change in pain score(PS)of the patient 3-5 days after the operation,and the patient satisfaction was recorded 4 months after the operation.Results:1)Clinical index: The gingival index(GI),bleeding index(BI),probing depth(PD),and gingival phenotype(GB)of the experimental group and the control group before tooth extraction show no significant difference except probing bleeding index.2)Changes in the width of buccal keratinized tissue 4 months after the alveolar ridge preservation: Buccal keratinized tissue in the mesial,middle,and distal aspects of the experimental group decreased by 0.6±1.3mm,0.2±1.1mm,0.4±1.3.mm,respectively;in the control group they were decreased by 0.8±0.8mm,0.8±0.7mm and 1.0±0.8mm,respectively.There was no significant difference between the two groups(P>0.05).3)The simultaneous bone augmentation rate: 4 patients in the experimental group required simultaneous bone augmentation with implant placement,and the simultaneous bone augmentation rate was 25%;10 patients in the control group required simultaneous bone augmentation with implant placement.The simultaneous bone augmentation rate was 66.7%,which was significant different between the two groups(P<0.05).4)Implant torque: The implant torque was 38.8±10.1N.cm in the experimental group and 36.4±11.5N.cm in the control group.There was no statistical difference between the two groups(P>0.05).5)Radiographic index1.Changes in vertical bone height at baseline and 4 months after tooth extraction:1.1.Bone height before extraction: The bone heights in the mesial buccal,middle buccal and distal buccal aspects of the socket in the experimental group were 4.5±3.6mm,4.6±3.3mm,and 5.2±3.9mm,respectively;while those in the control group were 6.9±3.1mm,6.6±2.6mm,7.3±2.8mm,respectively.There is no significant difference between the two groups(P>0.05);The lingual/palatal vertical bone height of the experimental group in the mesial,middle and distal aspects were 6.2±2.8mm,5.7±2.9mm,6.2±2.8mm,respectively;while the control group were8.1±3.5mm,7.5±3.0mm,7.8±3.4mm,respectively,there was no significant difference between the two groups(P>0.05).1.2.Bone height changes 4 months after surgery: In the control group,bone resorption in the mesial,middle,and distal parts of the lingual/palatal bone height was-0.9±1.2mm,-0.9±0.9,and-1.0±1.1mm,which are significantly different from those before surgery(P<0.05);the lingual/palatal bone height experimental group is-0.3±1.2mm,-0.5±1.2,-0.1±2.3mm,there is no significant difference between baseline and 4months after operation(P>0.05),and there is no statistical difference compared with the control group(P> 0.05).The average absorption of buccal bone height the control group in the mesial,middle,and distal aspects was-1.7±3.5mm,-1.1±1.7mm,and-2.1±1.6mm,which were significantly different from the baseline(P<0.05);in the experimental group buccal bone height were increased by 0.2±2.5mm,0.3±2.7 mm,0.1±2.8mm on average,and there was no significant difference between baseline and 4 months after surgery(P>0.05).the changes of bone height in mesial and distal area show statistical difference when compared with the control group;both the experimental group and the control group had significant increases of bone height in the center of the alveolar socket,the experimental group had an average increase of 6.6±3.5mm,and the control group had an increase of 3.9±3.5mm.There is no significant difference between the two groups.(P>0.05).2.Changes in ridge width between baseline and 4 months after tooth extraction:2.1.25% level: The experimental group had a significant increase in alveolar ridge width at the 25% level in the mesial,middle,and distal directions(P<0.05),the mesial 25% increased by 5.5±4.1 mm,the central25% increased by 5.5±3.8mm,the distal 25% increased by 4.1±5.4mm,and the distal 25% increased by 2.8±4.0mm.(P<0.05)2.2.50% level: The experimental group had a significant increase in alveolar ridge width at the 50% level in the mesial,middle,and distal directions(P<0.05),the mesial 50% increased by 1.1±2.9 mm,the middle50% increased by 4.5±4.6mm,and the distal 50% increased by 3.9±5.1mm.However,the increase of the ridge width in the control group was only observed at the mesial 50% level,and the increase was 1.8±3.3mm(P<0.05).2.3.75% level: When considering the changes of ridge width in mesial,middle,and distal aspects at the 75% level,the experimental group had an average increase of 1.3 ± 3.5 mm,1.2 ± 1.4 mm,and 2.6 ± 4.7 mm,respectively while the control group had an average bone resorption-0.5±1.5mm,-0.8±0.8mm,-0.2±2.1mm,respectively.3.Changes in socket volume: the average socket volume of the experimental group after tooth extraction was 816.8±290.4mm~3,and the average volume of the control group after tooth extraction was886.6±320.6mm~3.4 months after the operation,the volume of the alveolar socket in the experimental group increased by 245.7±183.3mm~3,and that in the control group increased by 122.9±78.9mm~3.There is a significant increase in socket volume between baseline and 4 months after surgery in both groups(P<0.05),but the increase in the experimental group is greater than that in the control group.6)Pain score and satisfaction of the patients: Pain and swelling score recorded by VAS showed that the pain intensity of patients in the experimental group and the control group decreased significantly within five days after surgery,and the pain score was only 0.79±0.98 in the experimental groups and 0.57±0.76 in the control groups(P>0.05).The visual analog scale for overall satisfaction submitted after 4-month followup showed that the overall satisfaction in both groups were high and there is no statistical difference.Conclusion:Alveolar ridge preservation/simultaneously augmentation with a resorbable membrane and DBBM-C in combination with PRF in posterior sites with severe socket walls deficiency(>50% bone loss)can result in better maintenance of ridge contour and more new bone generation in extraction socket.Reduction of rates of implant placed with simultaneous bone augmentation could also been noticed. |
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