Mandibular second molar periodontal status after third molar extraction.

BACKGROUND: Extraction and treatment of third molars have been cited as causing periodontal problems. To evaluate the long-term effects of third molar extraction on the periodontal health of the mandibular second molar, a comparison of the periodontal status was performed around 2 groups of mandibular second molars, with and without third molar extraction. METHODS: A total of 312 sites in 57 adult periodontitis patients were examined and the buccal and lingual locations of the mesial and distal root surfaces around the second molars were recorded. Two-hundred and thirty-two sites were experimental teeth; i.e., third molars had been surgically removed more than 5 years ago, 80 sites served as control molars; i.e., congenitally missing third molars. Clinical periodontal parameters including probing depth, attachment loss, and gingival recession and radiographic intrabony level were measured. The effects of the surgery and the examination (buccal or lingual) locations on the measurements were statistically analyzed. RESULTS: Neither extraction history nor examination location affected the probing depth on mesial surfaces. However, significant effects of the surgical history on the probing depth were observed on the distal surfaces. Similar results of greater attachment loss and radiographic alveolar bone loss were observed only at the distal sites of the experimental group. In addition, the increased radiographic bone loss was only found at the distal sites (adjacent to the surgical location) and not at the mesial sites (distant from the surgical location) on the experimental group. CONCLUSIONS: In this study, greater periodontal breakdown, including probing depth, attachment loss, and radiographic alveolar bone loss, was found at the distal sites, but not at the mesial sites, of the experimental molars where the third molar was surgically extracted compared with the control teeth (no surgery). In the experimental molars, more radiographic bone loss was found at the sites adjacent to the surgical location than at the sites distant to the surgical location. Therefore, we suggest that the surgical removal of the mandibular third molar may lead to a periodontal breakdown on the distal surface of the second molar. Periodontal re-evaluation after the initial healing of third molar extraction is indicated.     

Comparison of 2 flap designs in the periodontal healing of second molars after fully impacted mandibular third molar extractions.

PURPOSE: This investigation compared the effects of different flap designs on the periodontal health status of the mandibular second molar after the extraction of the adjacent impacted third molar. PATIENTS AND METHODS: Eighteen patients aged 16 to 32 years who required removal of bilateral impacted mandibular third molars were included in this study. The periodontal health of the second molar was evaluated preoperatively and at 1 week, 2 weeks, 4 weeks, and 12 months postoperatively. The third molars were removed by using the 3-cornered flap on the left side of the jaw and modified Szmyd flap on the right side. RESULTS: The mean probing depth (PD) at distal and buccal sites was significantly different between the flaps at 1 week, 2 weeks, and 4 weeks postoperatively (P < .05). There were no significant differences in preoperative and 1 year postoperative mean PD between the 2 flaps (P > .05). There was no significant difference in mean clinical attachment level between the flap sites at 1 year (P > .05). CONCLUSION: The modified Szmyd flap, which leaves intact gingiva around the second molar, has better primary periodontal healing than the 3-cornered flap after surgical removal of the fully impacted mandibular third molar.     

Influence of flap design on periodontal healing of second molars after extraction of impacted mandibular third molars

OBJECTIVE: The aim of this study was to compare the influence of two mucoperiosteal flaps on periodontal healing of adjacent second molars after extraction of impacted mandibular third molars. STUDY DESIGN: An envelope incision with a releasing incision anterior to the second molar (3-cornered flap) was used on one side and a Szmyd flap on the other side in 14 patients with bilateral impaction of mandibular third molars. The periodontal health of the second molars was evaluated before surgery and at 3 and 6 months postoperatively. A William's periodontal probe was used to measure the pocket depth, clinical attachment level, and bone level of the buccal and mesial surfaces of the second molars. The postoperative measurements were analyzed by using analysis of covariance, with the covariables being the preoperative measurements and variation factors being the type of flap used, the surface measured, and the time since the procedure. RESULTS: No statistically significant differences were found in comparing measurements of probing depth, clinical attachment level, or bone level for the 2 types of flap used or the 2 surfaces measured. However, there was a statistically significant increase in all 3 measurements from the 3-month to the 6-month postoperative time. CONCLUSION: Independent of the design of the mucoperiosteal flap used in extracting an impacted mandibular third molar, the periodontal condition of the adjacent second molar worsened from 3 to 6 months, although it remained within normal values.     

Use of orthodontic treatment as an aid to third molar extraction: a method for prevention of mandibular nerve injury and improved periodontal status

BACKGROUND: Impaction of mandibular third molars predisposes to pathological conditions including periodontal disease. Extraction of these teeth also may lead to damage to the nerve and to periodontal involvement of the second molars. This report describes a series of cases in which the third molars were orthodontically induced to erupt to prevent the sequelae associated with extraction. METHODS: Impacted mandibular third molars in 18 patients were surgically exposed following placement of an orthodontic appliance. Depending on the individual case, 1 of 3 approaches was used: attachment of a bracket, placement of a post in the root canal, or placement of an orthodontic wire through a bucco-lingual canal. After suturing the mucoperiosteal flap, the orthodontic appliance was activated. After the tooth erupted, it was removed and periodontal parameters were measured on the second molar. RESULTS: No damage to the inferior alveolar nerve was found. Probing depths on the second molar were reduced from 7.9 +/- 1.6 mm on the buccal and 7.4 +/- 1.0 mm on the lingual to 1.8 +/- 0.7 mm and 1.9 +/- 0. 7 mm, respectively. There was an average gain of 5.0 mm in attachment. Keratinized tissue increased from 2.9 +/- 0.7 to 3.8 +/- 0.6 mm. CONCLUSIONS: The interdisiplinary use of periodontics and orthodontics results in non-surgical removal of impacted mandibular third molars without damage to the inferior alveolar nerve and iatrogenic periodontal sequelae to the second molars.     

第三磨牙近中阻生对邻近第二磨牙龈沟液中MMP8和TIMP1的影响

目的:探讨第三磨牙近中阻生对邻近磨牙龈沟液中MMP8和TIMP1的影响。方法:选择64例口腔科就诊的战士,分为4组,A组下颌第二磨牙伴第三磨牙近中阻生,第三磨牙无冠周炎病史,龈瓣颜色正常;B组下颌第二磨牙伴第三磨牙近中阻生,6个月内第三磨牙有冠周炎病史,龈瓣颜色正常;C组下颌第二磨牙伴第三磨牙近中阻生,有冠周炎;D组无下颌第三磨牙,第二磨牙作为对照。收集下颌第二磨牙龈沟液,检测MMP8和TIMP1水平,同时测定第二磨牙龈沟出血指数、探诊深度和菌斑指数等指标。结果:MMP8和TIMP1各组间均有统计学差异(C组>B组>A组>D组)。MMP8/TIMP1 B组和A组之间无明显差别,其余各组间差异有统计学意义。临床指标中,C组的菌斑指数明显高于D组,A、B、C组的探诊深度大于D组。结论:第三磨牙近中阻生在无炎症状态时可引起第二磨牙龈沟液MMP8、TIMP1、MMP8/TIMP1和探诊深度等牙周炎潜在致病因素的变化,出现冠周炎症时变化更加显著。     

Relationship between periodontal furcation involvement and molar cervical enamel projections

A total of 78 individuals ages 21 to 61 years with periodontal furcation involvement was examined for the presence of cervical enamel projections on the buccal surfaces of molar teeth. The furcal defects and cervical enamel projections (CEPs) of molars were diagnosed by probing, periapical roentgenographs, flap operation and inspection. Plaque index (PlI) and gingival index (GI) were recorded for the buccal and lingual surfaces of molars examined. The percentage of CEPs in the 78 individuals examined was 67.9%. The prevalence of CEPs in all molars examined was 45.2%. The prevalence of CEPs in molars with and without furcal involvements were 82.5% and 17.5%, respectively. The frequency of CEP in molars occurred in the following order: mandibular first molars, maxillary first molars, mandibular second molars and maxillary second molars. Statistical analyses (Chi-square test) revealed a significant difference between periodontal furcation involvements and the presence of CEPs. Results of this study also indicated that the furcal involvements with CEPs were associated with poor oral hygiene as measured by GI and PlI.     

Residual periodontal defects distal to the mandibular second molar 6-36 months after impacted third molar extraction

AIM: This retrospective study investigated the periodontal conditions distal to mandibular second molars 6-36 months after routine surgical extraction of adjacent impacted third molars. METHOD: Subjects were randomly selected by systematic sampling from computer records of 3211 surgical mandibular third molar extractions in the Hong Kong dental teaching hospital. Records and pre-extraction radiographs of the selected cases were retrieved. Selected subjects (n = 283) were invited for an interview followed by a clinical examination. Community Periodontal Index (CPI) protocol was used for the assessment of the general periodontal status (excluding the mandibular second molar of interest, i.e. the subject tooth) followed by a detailed periodontal examination of the subject tooth. RESULTS: In all, 158 subjects, aged 29 +/- 7 years, were examined with only 6% (nine subjects) having a highest CPI score of 4 (excluding the subject tooth), but local periodontal defects were prevalent at the distal surface of subject mandibular second molars: mean probing pocket depth (PPD) was 5.4 +/- 1.9 mm with 67% (106 subjects) exhibiting PPD >or= 5 mm and 23% (36 subjects) exhibiting PPD >or= 7 mm; mean recession was 0.8 +/- 1.0 mm; bleeding on probing 96% and suppuration on probing 5%. Multiple linear regression analysis was used to analyse the effects of 12 independent variables on the PPD at the distal surface of the involved mandibular second molar. Three possible risk indicators (P < 0.001, R2 = 0.27) associated with localised increased PPD at the distal surface of the mandibular second molars were identified: 1) third molar 'mesio-angular' impaction; 2) pre-extraction crestal radiolucency and 3) inadequate post-extraction local plaque control. CONCLUSION: The results suggest that periodontal breakdown initiated and established on the distal surface of a mandibular second molar in the vicinity of a 'mesio-angular' impacted third molar evidenced by pre-extraction crestal radiolucency in association with inadequate plaque control after extraction can predispose to a persistent localised periodontal problem.     

比较非手术治疗对重度慢性牙周炎磨牙不同部位牙周病变的疗效

目的:根据磨牙中重度慢性牙周炎发生不同部位病变比较非手术治疗的疗效。方法:根据单个磨牙深牙周袋发生的部位(颊侧或舌/腭侧)将收集的上、下颌磨牙各分为两组(上颌I组、上颌II组、下颌I组、下颌II组),观察各组治疗前后牙周指标的变化,比较疗效差异。结果:4组病例治疗后6周各项牙周指标均较基线有明显改善,差异有显著性(P<0.01)。上颌两组间及下颌两组间比较,可见6周时上颌II组的PD、BI、CAL均高于上颌I组,差异有显著性(P<0.01);下颌II组的PD、BI、CAL高于下颌I组,差异有显著性(P<0.01)。结论:发生在磨牙的牙周炎症无论是上颌还是下颌,颊侧病变的预后均好于舌/腭侧,差异有显著性。     

下颌智齿阻生类型及其邻牙远中邻面患龋情况的对称性初探

目的 调查下颌第三磨牙生长情况的对称性及其对相邻第二磨牙远中邻面龋患病情况的影响,为临床早期预防性拔除下颌智齿提供依据。方法 纳入2019年11月1日至2019年11月23日在上海交通大学医学院附属仁济医院口腔科拍摄的全景片196张,调查其双侧下颌第三磨牙的对称性,通过卡方检验分析不同阻生类型的下颌第三磨牙与相邻第二磨牙远中邻面龋患病情况之间的关系。结果 双侧下颌第三磨牙对称者187例,占比95.41%。Winter分类中垂直阻生对称性（79.2%）显著高于近中阻生（47.6%）与水平阻生（59.1%）（P=0.001）; Winter分类为近中阻生（46.4%）和水平阻生（38.4%）的下颌第三磨牙,其相邻第二磨牙远中邻面龋发生率显著高于垂直阻生（23.6%）（P=0.001）。结论 下颌智齿具有对称性;为预防相邻第二磨牙远中邻面龋,近中阻生及水平阻生的下颌第三磨牙应在临床上早期预防性拔除。     

Marginal flap versus paramarginal flap in impacted third molar surgery: a prospective study

OBJECTIVE: A clinical prospective study was carried out to compare 2 flap designs-marginal and paramarginal-that are used during impacted third molar surgery. MATERIALS AND METHODS: Twenty-seven healthy patients (ages 17 to 31 years) who underwent surgical removal of 4 impacted third molars, including 54 lower and 54 upper, were included. A marginal flap was used in 1 randomly chosen half of the jaw, and a paramarginal flap was used in the other half. The influence of these flaps on wound healing, periodontal pocket depth of the adjacent second molar, pain, trismus, and swelling was studied. RESULTS: Wound dehiscences developed in 8 paramarginal flap cases, whereas none occurred with the use of a marginal flap. The buccal and distal probing depths of the adjacent second molar were significantly bigger in marginal flaps at 5 and 10 days after surgery. However, the probing depth was similar with the use of both techniques at 3 months. Pain, trismus, and swelling were similar with both techniques. CONCLUSIONS: We found no advantages to the use of a paramarginal flap instead of a traditional marginal flap for removing impacted third molars.     

改良舌弓治疗下颌第一磨牙异位萌出的临床应用

目的探讨改良舌弓治疗下颌第一恒磨牙异位萌出的临床效果。 方法选择于2018年1月至2021年6月于东莞健力口腔医院正畸科就诊的15例下颌第一恒磨牙异位萌出的患儿，年龄7 ~ 8岁，其中5例双侧、10例单侧，以第二乳磨牙作为直接支抗，通过传统的下颌舌弓焊接远端牵引钩，在异位萌出的恒磨牙面粘接舌侧扣联合链状橡皮圈牵引异位萌出恒磨牙向远中，以达到其正常的生理位置。使用SPSS 20.0统计软件分别对治疗前后作为直接支抗牙的第二乳磨牙与异位的第一恒磨牙的倾斜角度与冠近远中高度进行统计学分析，采用配对t检验进行对比，以P<0.05为差异有统计学意义。 结果第二乳磨牙治疗前的倾斜角度为64°±3°，治疗后为63° ± 4°，差异无统计学意义（t = 1.399，P = 0.178）。同样，第二乳磨牙治疗前的近远中冠高比（85% ± 4%）与治疗后（84% ± 4%）相比，差异无统计学意义（t = 0.608，P = 0.550）。异位的下颌第一恒磨牙治疗前的倾斜角度为52° ± 6°，治疗后为69° ± 4°，差异有统计学意义（t = -10.423，P<0.001）。异位的下颌第一恒磨牙治疗后的近远中冠高比（90% ± 3%）高于治疗前（80% ± 5%），差异有统计学意义（t = -8.231，P<0.001）。 结论改良舌弓临床操作简便，提供的支抗良好、充分，能有效治疗下颌第一恒磨牙异位萌出。     

Assessment of lingual nerve injury using different surgical variables for mandibular third molar surgery: a clinical study

The objective of this study was to investigate the incidence of sensory impairment of the lingual nerves following lower third molar removal and to compare the outcome with various operative variables. A total of 1200 mandibular third molars were removed under local anaesthesia. Predictor variables were categorized as lingual flap retraction, tooth sectioning, and buccal guttering. The outcome variable was the presence or absence of lingual nerve impairment. Different operative techniques were performed to identify independent predictors. Of the 1200 patients, 67 (5.6%) experienced transient sensory impairment at the 1-week follow-up. In all cases this resolved completely during the study period, except for four (0.3%) patients who suffered permanent impairment of lingual nerve function. Factors that predicted lingual nerve injury were lingual flap retraction, tooth sectioning, and buccal guttering. The incidence of lingual nerve injury was greater when combinations of these operative variables were used.     

Accuracy of Partial‐Mouth Examination Protocols for Extent and Severity Estimates of Periodontitis: A Study in a Chinese Population With Chronic Periodontitis

Background: Partial‐mouth periodontal examination (PMPE) has been widely used in periodontal epidemiologic studies. In this study, the authors evaluate the accuracy of extent and severity estimates from PMPE protocols in a Chinese population. Methods: The study enrolled 200 individuals with periodontitis, ages 22 to 64 years. Full‐mouth examination was performed to determine probing depth (PD), attachment loss (AL), and bleeding on probing (BOP) at mesio‐buccal (MB), mid‐buccal (B), disto‐buccal (DB), mesio‐lingual (ML), mid‐lingual (L), and disto‐lingual (DL) sites per tooth. Extent and severity estimates from 15 PMPE protocols were derived from and compared to full‐mouth data. Relative bias (RB) and intraclass correlation coefficients (ICCs) were calculated. Bland‐Altman plots were used to evaluate the agreement patterns across disease levels. Results: Of the 15 PMPE protocols, the random half‐mouth six‐sites per tooth (r6sites) protocol performed best in both extent (AL ≥2, ≥4, or ≥6 mm; PD ≥4 or ≥6 mm; and BOP) and severity (AL and PD) estimates, with RB within 5.0% and ICCs ≥0.950 in most cases. MB‐B‐DB and MB‐B‐DL protocols generally resulted in RB within 20.0% for extent and within 5.0% for severity. Protocols involving only interproximal sites (MB‐DB, MB‐DL, and MB‐DB‐ML‐DL) showed good accuracy in AL (RB within 20.0% for extent and within 3.0% for severity), but overestimated PD (RB 12.5% to 54.2% for extent and >10.0% for severity). The community periodontal index teeth protocol caused severe overestimation of up to 110.4% for extent and 14.6% for severity. Conclusion: The r6sites protocol is best for assessing extent and severity for AL, PD, and BOP under the study conditions.     

Cemental tear on a mandibular second molar: a case report

A cemental tear is a special kind of root fracture that may cause rapid and localized periodontal destruction. Most cemental tears have been reported on bicuspids and incisors. Here we present a case of cemental tears on both the right mandibular first and second molars. The patient was a 72-year-old man who showed gingival swelling and a deep pocket over his right mandibular second molar as well as a deep periodontal pocket on the distolingual aspect of the first molar. During exploratory flap surgery, a detached root fragment on the mesial side of the second molar and a small root fragment on the lingual surface of the first molar were found and removed for biopsy. After histopathological examination, both root fragments were confirmed to be cemental tears. The periodontal defects were treated by osseous grafting and guided tissue regeneration. A postoperative probing depth of 4 mm on the second molar was recorded at 3 months and remained stable for 5 years. Where marked periapical and periodontal bony destruction are present, a cemental tear should be considered as a possible diagnosis, even in the molar teeth, for early treatment to improve prognosis.     

Stress distribution produced by the correction of the mandibular second molar in lingual crossbite

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a mandibular posterior crossbite appliance used for the correction of mandibular second molars in lingual version. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alvelolar bone and ivory-colored resin teeth. The model was observed anteriorly and posteriorly with a circular polariscope and photographically recorded before and after activation of mandibular posterior crossbite appliances. An uncontrolled tipping and an extrusive force were generated when the traction force was applied on the buccal surface of the mandibular second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the lingual surface of the mandibular second molar. We concluded that to escape the extrusion and uncontrolled tipping that creates occlusal interferences associated with the correction of mandibular second molars in lingual version, the lingual traction force is more useful than the buccal traction force.     

铸造支架联合NITI悬臂梁矫正舌倾下颌磨牙的临床效果评价

目的 评价NITI悬臂梁在矫正舌倾下颌磨牙中的临床效果。方法 选择16例单侧下颌第二磨牙舌倾的病例为研究对象,带垫铸造支架连接双侧下颌后牙,提供颌内支抗、解除咬合锁结,0.018英寸×0.025英寸或0.019英寸×0.025英寸NITI悬臂梁提供颊向旋转力矩和压低力。采用Graphpad Prism 6.0 软件对治疗前、后所测数据进行配对 t 检验。结果 所有患牙均获得直立,牙轴变化24°±1.2°（P<0.01）,近中舌尖到正中矢状面垂直距离变化（3±0.8） mm（P<0.05）,牙周状况良好,咬合关系稳定。结论 铸造支架联合NITI 悬臂梁可提供有效力学机制,矫正舌倾下颌磨牙。     

成人下颌磨牙后间隙与第三磨牙关系的三维研究

目的 测量成人下颌磨牙后区大小并分析其与第三磨牙状态的关系.方法 采用CBCT对86例成年骨性Ⅰ类均角患者根据第三磨牙状态进行分组,从三维方向对右侧下颌磨牙后间隙进行测量.在水平面上沿POL线(第一磨牙与第二磨牙颊尖连线)测量下颌平面(以及从下颌平面向根方2 mm的平面)处第二磨牙牙冠到升支前缘的最短距离.牙根层面...     

Anatomical considerations for the spread of odontogenic infection originating from the pericoronitis of impacted mandibular third molar: computed tomographic analyses

OBJECTIVES: The aims of the present study were to clarify the anatomy of impacted mandibular third molars in relation to surrounding structures and to investigate the pathway of infection originating from pericoronitis of this tooth. STUDY DESIGN: Computed tomography (CT) images were evaluated in 87 patients with uninfected mandibular third molar impaction and in 12 patients with infection originating from an impacted mandibular third molar. In uninfected patients, bony features around the impacted crown were investigated together with the relationship between the crown and surrounding muscles. In infected patients, involvements of bony and soft tissue structures were evaluated according to the disappearance of cortices and lateral asymmetry of density and shape in the spaces and muscles. RESULTS: In uninfected patients, the disappearance of the lingual cortical plate was observed in 48 (35.3%) impacted molars, while only in 11 (8.1%) teeth for buccal cortices. The cortical thickness was thinner on the lingual side than the buccal side. Sixty-five percent of the masseter muscle horizontally overlapped the crown, while almost all of the medial pterygoid muscle was posteriorly situated apart from the crown. The mylohyoid muscle horizontally overlapped the crown at below or intermediate vertical positions. In infected patients, the involvement of lingual structures was more frequently observed than that of buccal structures. The mylohyoid muscle was involved in 10 (83.3%) of 12 patients. Among them, 8 showed submandibular space involvement. CONCLUSION: CT findings supported the clinical observations of infection spread in patients with pericoronitis of the impacted mandibular third molar. CT appeared to be an effective tool for investigating the pathway of infection originating from the pericoronitis of impacted mandibular third molars.     

Change in third molar angulation and position in young adults and follow-up periodontal pathology.

PURPOSE: This study was designed to assess changes in third molar position and angulation in young adults and the resulting third molar periodontal probing (PD) status. PATIENTS AND METHODS: Data derived from patients with 4 asymptomatic third molars with adjacent second molars enrolled in an institutional review board approved longitudinal trial. Inclusion criteria for the trial dictated that patients be healthy and 14 to 45 years of age. Panoramic radiographs were analyzed for third molar angulation as compared with the long axis of the second molar (mesial/horizontal > or =25 degrees ) and eruption to the occlusal plane. Full mouth PD including third molars was conducted at follow-up. At follow-up, PD > or =4 mm distal of second molars or around third molars was considered important clinically. RESULTS: Data from 237 patients were available. Median age was 25.9 years (interquartile range [IQ], 22.1 years, 32.8 years). With a median follow-up of 2.2 years (IQ, 2.0 years, 3.7 years), 44% of impacted maxillary third and 26% of impacted mandibular third molars changed angulation or position. One third of vertical/distal impacted third molars in both jaws and 11% mesial/horizontal mandibular third molars erupted to the occlusal plane during follow-up from baseline. If mandibular third molar angulation as compared with the long axis of the second molar was mesial/horizontal > or =35 degrees , only 3% erupted to the occlusal plane. At follow-up, 11% of the 125 impacted maxillary third and 29% of the 133 impacted mandibular third molars had PD > or =4 mm. Similarly, 11% of the 307 maxillary third molars at the occlusal plane had PD > or =4 mm, but 51% of the 312 erupted mandibular third molars were affected. CONCLUSION: A change in third molar position or angulation was common. Erupted mandibular third molars were more likely to have PD > or =4 mm.     

Periodontal healing after mandibular third molar surgery--A comparison of distolingual alveolectomy and tooth division techniques

The purpose of this study was to compare the periodontal healing of mandibular second molars after the removal of impacted mandibular third molars using distolingual alveolectomy and tooth division techniques. A total of 120 consecutive healthy patients who presented with bilaterally impacted mandibular third molars were included in this study. The same operator removed the impacted third molars on both sides in all patients. The third molar on one side was removed by distolingual alveolectomy using a chisel, whereas the contralateral tooth was removed by the tooth division technique using burs. Attachment level, periodontal pocket depth and bone healing distal to the mandibular second molars were assessed at 7 days, 3 months and 6 months after surgery. The results showed better periodontal healing and bone healing when distolingual alveolectomy was employed, especially in the removal of deeply impacted mandibular third molars.